Original Title: Lightning Protection Engineering Design and Construction Organization Plan (I) The lightning protection project needs to be implemented in an organized and step-by-step manner to ensure the quality and duration of the project. Today, Junhe Electronics takes a project as an example to share with you the template of lightning protection engineering design and construction organization scheme for reference only, as follows: I. Lightning protection design scheme 1. Project overview The project is located in XX Town, XX County, XX Province, which is surrounded by mountains on three sides. The project is located in the south of the XX fault zone. There are few soil layers in the project yard, no vegetation, mostly rocky mountains, and the soil resistivity is high. The available land area around the building is small, there is no vegetation soil layer, and it is mainly rock. The measured soil layer is 1420 Ω · m (the surface layer is backfill soil), and the grounding coefficient varies with the season. The measured soil resistivity of highly weathered dolomite in L201 and L202 buildings is 20000 ohm · m. 2. Analysis of design scheme There are many grounding methods for lightning protection, such as (1. Soil replacement method, 2. Artificial soil treatment method (chemical treatment of soil), 3. Deep buried grounding electrode method, 4. Multi-branch external grounding device method, 5. Grounding module grounding method, 6. Sewage introduction method, 7. Deep well grounding method). There are two grounding methods suitable for L201 and L202; Deep well grounding method and grounding module grounding method. Disadvantages of grounding method of grounding module: Due to the shallow soil layer of the project site, the geographical environment changes significantly in four seasons, and the rainfall is not balanced, which objectively causes the instability of soil temperature, humidity and water retention, and will affect the stability of the resistance of the whole ground network. It destroys the geological structure, occupies a large area, and the land used becomes dead and can not be reused. The service life of the module is short, the material composition is complex, ranging from several hundred yuan to several thousand yuan, and the module itself is fragile, which will affect the instability of the resistance value. The distance between the grounding grid of the lightning tower and the grounding grid of the building foundation is too close, which may lead to the formation of ground potential counterattack, resulting in serious consequences such as equipment damage. Module grounding needs to change the soil, but it is difficult for us to get the soil, and it also depends on what kind of soil (sandy soil, loess, black soil) will affect the resistance. The modules are connected by flat steel, which is easy to corrode and also affects the resistance. The extensive use of common resistance reducing agents has an impact on groundwater and soil quality, which is related to personal health and safety! In terms of price comparison, if better materials are used and products meet the requirements of national standards, the price difference between deep well grounding and deep well grounding is not very large. Advantages of deep well grounding method: The deep well grounding mode eliminates the influence of temperature difference in four seasons and ensures the stability of grounding grid resistance. It occupies a small area and will not affect the land use. The use of long-acting physical resistance reducing agent, green environmental protection, pollution-free, long life, in line with the standards of the national testing department, the first phase of the project experience can be verified. The ion grounding electrode has the advantages of high conductivity, long service life and stability. All the connections are made by copper wires, so the corrosion degree is low, the resistance is small and the resistance value is stable. Expand the full text Based on the above analysis, the comprehensive grounding scheme based on deep well grounding is the most effective, economical and practical grounding scheme. 3. Design basis The main contents of the current relevant specifications, regulations and acceptance standards for installation works issued by the People's Republic of China are as follows: Design Code for Protection of Structures against Lightning GB50057-2010 Technical Code for Protection against Lightning of Building Electronic Information System GB50343-2012 Installation Drawings of Lightning Protection Facilities for Buildings 99 D501-1 Code for Design Review and Completion Acceptance of Lightning Protection Devices (Order No.21 of the State Meteorological Administration) Design Code for Lightning Protection and Grounding Engineering of Communication Bureaus (Stations) YD 5098-2005 Standard for Grounding of AC Electrical Installations DL/T621-1997 According to the geotechnical investigation report of Gaoxin Phase III, it is shown as follows: The first layer: artificial fill: mainly composed of clayey silt, containing plant roots and organic matter, located on the artificially reclaimed slope, with a thickness of 0.3 ~ 1.5m. Layer 2: loessial clayey silt and silty clay of Quaternary Upper Pleistocene eluvium, alluvium and diluvium, slightly wet-wet, slightly dense-medium dense, with developed voids, containing a small amount of gravel and plant roots. The thickness of this layer is 0.5 ~ 3.5m. Layer 3: strongly weathered dolomite Layer 4: Moderately weathered dolomite Layer 5: Weathered dolomite According to the geological conditions of the test site, the geological environment of the grounding grid is poor and the soil resistivity is high. According to the design requirements of the test area, the grounding resistance of L201 and L202 buildings is less than 1 Ω. If each building is made separately to meet the design requirements, not only the layout and working surface of the site can not meet the construction requirements, but also the investment is very huge, resulting in the waste of repeated construction and investment. Considering the technical feasibility and rationality and avoiding the waste of investment, we suggest that several buildings should share the grounding network, and the resistance value should be less than 1Ω according to the minimum value of the design requirements of several buildings, which can meet the original design requirements. Technical analysis Based on the above requirement of joint grounding, the power frequency grounding resistance of the grounding grid is R ≤ 1Ω, and the theoretical calculation of the grounding resistance of the whole grounding grid in this project is as follows: Calculation of vertical grounding resistance: According to the geotechnical engineering investigation report, the first layer (0-1.5m) of the site and its vicinity is artificial fill, and the soil resistivity distribution is about 350-600Ω · m; the second layer (1.5-5m) is loess-like silty clay and heavy silty clay, containing a small amount of sand and stone, and the soil resistivity distribution is about 800-1300Ω · m; The third layer (5-9.4m) is mostly strongly weathered white rock layer and moderately weathered white rock layer, and the soil resistivity distribution is about 1600-2100Ω · m; the fourth layer (9.4-120m) is slightly weathered white stone layer, and the soil resistivity distribution is about 2400-3800Ω · m. According to the geological survey report, there is no water layer at 100m, and there is a 120m deep well in the plant area. Assuming that there is a water layer below 120m, the soil resistivity distribution is about 20-70 Ω · m. The layering calculation formula shall be in accordance with DL/T621-1997 Standard for Grounding of AC Electrical Installations; According to the calculation, the horizontal grounding resistance in the grounding grid is RO = 1. 56 Ω. When the resistance reducing agent is added around the horizontal connecting copper wire, the average resistivity of the soil can be reduced, and the resistance reducing rate is 0. 2. At this time, the horizontal grounding resistance in the joint grounding grid is RO = 1. 25 Ω. Calculation of compound grounding resistance After comprehensively considering the combination of deep well grounding electrode and horizontal connection copper wire, its grounding resistance shall be calculated according to DL/T621-1997 Standard for Grounding of AC Electrical Installations: after the combination of deep well grounding electrode and copper wire, the grounding resistance of the combined grounding network of 6 deep wells Rx = 0.74Ω Conclusion According to the above design method, the power frequency grounding resistance of the joint grounding grid is less than 1Ω, which meets the engineering requirements of Party A. Similarly, according to the formula, a 130m (according to the geographical situation, the drilling depth should reach more than 15m after the visible water layer, so the depth should be determined according to the actual situation) grounding deep well is drilled between the two towers (see the construction drawing) at the lightning tower of L201 and L202 buildings, which is the common grounding well of the two lightning towers. The theoretical prediction can meet the design requirement that the impulse resistance is less than or equal to 10Ω, and if the requirement cannot be met, two nearby deep wells can be jointly grounded. (According to 4, 2 and 1 of Code for Design of Lightning Protection of Buildings GB50057-2010, independent lightning rod, overhead lightning wire or overhead lightning network shall be equipped with independent lightning device, and the impulse grounding resistance of each downlead shall not be greater than 10Ω. In areas with high soil resistivity, the impulse grounding resistance can be increased appropriately, but in areas below 3000Ω m, the impulse grounding resistance should not be greater than 30Ω. Because the geological survey report States that water can be seen below about 100 meters, the value used in the formula is 120 meters. 4. Design quantity According to the calculation of grounding resistance of deep wells, it is necessary to drill 6 grounding deep wells (about 130 meters each) between buildings in parallel to meet the design resistance requirements. The deep well is connected to the grounding grid of the building by 95mm2 copper wire brazing. A total of 18 KS-JD-3000 ion grounding electrodes (3 for each well), 1518.5 meters of 95mm2 copper wire connecting line and 32.17 tons of resistance reducing agent are required for construction. A total of 18 KS-JD-3000 ion grounding electrodes, 1518.5 meters of 95mm2 copper wire and 32.17 tons of resistance reducing agent are required for construction. The above design is calculated according to the theoretical value. In case of deviation between the grounding resistance value and the calculated value due to the change of geological conditions in the construction practice, the grounding unit of the deep well shall be increased or decreased according to the measured value. Until the resistance value required by the project is reached. 5. Construction scheme and main subdivisional construction methods (1) General principle of construction Reasonable arrangement of working procedures, close connection of working procedures, scientific and standardized management, and full utilization of man and machine (2) Construction scheme Excellent construction personnel shall be selected to organize the construction meticulously. During the construction, parallel crossing and flow operation shall be adopted to optimize the working procedures so as to ensure the overall construction period. Pay attention to safe construction to avoid personal injury and property loss. Strengthen the management of key sub-items, take the overall situation into account and manage scientifically. (3) Construction process Surveying, positioning and setting out shall be carried out in combination with the site and drawing dimensions to excavate the trench of the grounding grid, install the well drilling equipment, drill the well, bury the grounding electrode, grout the deep well, connect the grounding grid and reduce the resistance of the grounding grid for backfilling. (4) Construction technology Dig a trench Excavate the grounding grid trench. Excavate the grounding grid connection trench according to the drawing. The width of the upper part of the trench is 1000 mm, the bottom of the trench is 1000 mm, and the depth of the groove is 800 mm. Punch Because of the complexity of the formation, the combined drilling method of mud positive circulation and air Dth hammer is adopted. According to the geological survey report, the thickness of strata 1 ~ 5 is 5 to 10 meters, the original soil layer is silty clay with broken stones, and the broken fissures in the strongly and moderately weathered section are filled with clay. The process adopts Ф219 mm bit mud positive circulation rotary drilling, and in case of formation collapse, the casing is lowered to protect the hole. Air Dth hammer was used to drill the No.6 formation. Features of Dth hammer (air hammer): Air drilling is one of the most popular drilling methods in the world. As a new drilling tool in air drilling, Dth hammer has great application prospects. 1) less gas consumption; 2) that structure is simple, the reliability is high, and the requirement of various pressure conditions are met; 3) The optimized design of the patented technology system can maximize the use of the energy of the air compressor; 4) The hammer teeth of the new air hammer effectively alleviate the wear and fracture of the hammer teeth and greatly improve the pure drilling time; 5) High-hardness metal on the outer layer of bit teeth: compact, hard and wear-resistant; strong and tough metal on the inner layer : Good toughness, impact resistance, not easy to break. Dth hammer is also called pneumatic hammer, which uses compressed air as power medium to complete percussive rotary drilling and has the characteristics of air flushing drilling. Compared with the percussive rotary drilling with high-pressure water or mud as the power medium, the pneumatic Dth hammer rotary drilling has double efficiency. Important link of pore-forming 1) Overburden drilling A carbide bit was used for rotary drilling and the φ219 mm iron casing pipe was lowered. The key to the hole forming process of this project is to seal the gap between the protective pipe and the orifice tightly, especially in loose gravel strata, this step is particularly important. 2) Rock drilling Vibrating down-the-hole hammer is used for drilling, which is characterized by no coring, dth drill bits , complete crushing of the hole bottom, large amount of cuttings, and all of them are carried out of the hole by high-speed airflow. 3) Axial pressure (weight on bit) According to the principle of rock breaking by Dth hammer, rock is mainly broken under the action of impact dynamic load, so the drilling efficiency of Dth hammer mainly depends on the size of impact energy and the number of impact frequency. The axial pressure is used to overcome the upward pushing force generated in the cylinder when the impactor pushes the piston downward, so as to ensure that the impact energy is effectively transmitted to the drill bit. Generally, the weight on bit is 1.3-1.6T. 4) Drilling speed The drilling speed of the drilling tool is mainly determined according to the nature of the rock, the diameter of the bit, the impact energy and the impact frequency. The reasonable rotation speed shall ensure that the rock is broken within the optimal impact gap. Generally, the diameter of the borehole is about 200mm, 30-50r/min for soft strata, 20-40r/min for medium hard strata, and 10-30r/minute for hard strata. 5) Air supply volume During Dth hammer drilling, the compressed air has two functions: one is to provide energy for the movement of the impactor piston; the other is to carry cuttings and cool the drill bit. Therefore, the amount of air supply is determined on the one hand according to the amount of air consumption required by the Dth hammer used, and on the other hand to ensure the upward return air speed of the annular space of the drill pipe. Drilling air supply: It is mainly related to the annular clearance between the drill pipe and the hole wall. Q≥VK60(D2-d2)∏/4 Q-air supply, m3/min D-aperture, m D-diameter of drill pipe, m V-upward return wind speed, generally V ≥ 15m/s K-coefficient, generally about 1.3. In order to make full use of the air compressor, the annular clearance between the drill pipe and the hole wall should be reduced as much as possible. The hole diameter shall be reduced as much as possible under the condition that the installation of pumping equipment is satisfied. In addition, increasing the outer diameter of the drill pipe is also an effective way to reduce the annular clearance. 6) Wind pressure In the process of Dth hammer drilling, the pressure of the air compressor is the sum of various pressure losses in the whole compressed air flow channel. When the Dth hammer drills in the dry hole section, the air supply pressure is the sum of the working pressure of the Dth hammer and the pipeline pressure loss. When there is water in the hole, it is mainly determined by the depth of the hole, the buried depth of the water level in the hole and the water yield. Generally, when there is water, the air supply pressure is about 1.3 times of the hole depth (100m hole depth is 1MPa). Burying of grounding electrode For well entry operation, according to the design drawings, there are three grounding electrodes in each well, 95mm ² copper wire is used for welding between the grounding electrodes, anti-corrosion treatment is carried out for the welding spots, the grounding electrodes are placed section by section to the required depth, and the wellhead is positioned and fastened; High conductivity: Under the same grounding area, the grounding efficiency is 60 times that of the traditional method. Theory and practice show that the resistance in a very small range around the grounding body accounts for 90% of the overall grounding resistance in a uniform soil environment. The mix ratio of that filler material ensure that the resistivity of the filler material is extremely low, and the filler material can effectively permeate into the surrounding soil, thereby greatly improve the resistivity of the surrounding soil. On the other hand, the filler can penetrate into the surrounding soil and form a root-shaped diffusion structure, which greatly increases the effective contact area between the grounding body and the ground and reduces the grounding resistance. At the same time, the vertical grounding mode also effectively reduces the grounding resistance. Long-term effect: Experimental data analysis shows that the effective service life of the product can reach 50 years. The combination of the filler formula and the metal material of the rod body enables the surface of the metal rod body to form a conductive anticorrosive protective film, thereby preventing the corrosion of metal. The unique active ion automatic replenishment mechanism keeps the active ion content in the soil stable, thus maintaining low grounding resistance. The unique process measures ensure that the connection point of the grounding system realizes the true meaning of anti-corrosion. Stability: The product has high stability and is not affected by seasonal factors such as temperature, soil moisture content and the like. Small floor area: the floor area of each grounding unit is less than 0.1m2. It is especially suitable for use in urban grounding construction with dense buildings, and can be used as both an independent grounding body and an additional auxiliary grounding electrode. (4) Grouting During the grouting operation, the mixed resistance reducing agent is injected into the bottom of the deep well through the grouting pump and the conduit, so that the accumulated water in the deep well can be discharged. If necessary, the wellhead can be sealed with anchoring cement, and the high-pressure grouting pump can be used to force grouting into the well, so that the resistance reducing agent can penetrate into the soil along the rock and soil crevices, and the resistance reducing agent in the deep well can be poured compactly until the thick slurry of the friction reducing agent gushes out. (5) Grounding grid welding For grounding grid connection, the formed grounding deep well shall be electrically connected with 95 mm ² copper wire by means of hot melt welding. The welding length shall not be less than 80 mm. The welding seam shall be full and have sufficient mechanical strength. There shall be no slag inclusion, undercut, crack, false welding, air hole and other defects. After the coating at the welding position is knocked clean, it shall be brushed with asphalt for anti-corrosion treatment. When the ground grid is less than 3m away from the entrance and exit of the building or crossing the road during connection, the method of pressure equalizing belt shall be adopted or a gravel layer with a thickness of 150mm shall be laid on the resistance reducing agent, and its width shall not exceed 2m. (6) Resistance reduction of horizontal grounding grid For resistance reduction of the grounding grid, the resistance reducing agent of 30 kg/m shall be poured into the excavated trench, and the resistance reducing agent shall be mixed with water to form a paste, which shall be poured into the trench to wrap the copper wire, and then filled with fine soil and tamped. The trench of the whole project is about 1871 meters long. According to the dosage of 30 kg/m of resistance reducing agent, 28 tons of resistance reducing agent are needed. For backfilling construction, all excavated parts shall be backfilled with original soil, and the soil with high resistivity (sandy soil, stony soil, etc.) shall be replaced with swamp soil, black soil and garden soil for backfilling, and gravel layer shall be added when crossing with roads and pipelines. Principle of long-acting physical resistance reducing agent Physical resistance-reducing agent (also known as long-acting resistance-reducing agent) is made of macromolecular water-absorbing material and electronic conductive material, which contains fine graphite, bentonite, curing agent, lubricant, conductive cement, etc. It is non-toxic, odorless, non-corrosive, and will not pollute underground water sources, and meets the national environmental standards for high-quality soil. This is particularly important because many grounding constructions require well drilling operations and permeable layers. When the physical resistance reducing agent is used, no chemical reaction occurs and no new substance is produced. But only depends on the powdery structure and good conductivity of the resistance reducing agent itself to produce an auxiliary resistance reducing effect on other grounding bodies of the grounding grid. Its principle of action is equivalent to expanding the grounding area of other grounding bodies and increasing the current flow surface. Thereby reducing the contact resistance thereof. In addition, due to the corrosion resistance of the material of the physical resistance reducing agent, the use of the physical resistance reducing agent to wrap other metal grounding bodies is also a protection for the metal grounding bodies. Physical properties of resistance reducing agent 1. It is completely a physical resistance reducing agent, which eliminates corrosive electrolyte, and uses non-electrolyte carbon powder as conductive material to improve the corrosion resistance of metal electrodes. 2, the conductivity is not affected by acid, alkali, salt, temperature, humidity and other changes, with good moisture absorption, heat preservation, anti-freezing function. And 3, the grounding resistance value of the grounding grid can be reduced, the resistance reduction rate can reach 50 to 90%, the soil resistivity can be improved for a long time, and the grounding resistance value is stable. 4. Insoluble good conductor, which will not reduce the conductivity due to the decline of groundwater level or drought, nor will it be lost due to excessive rainwater. 5. Good voltage equalization can improve the potential distribution, thereby reducing the step voltage and protecting personal safety. 6, high temperature and cold resistance, high pressure impact resistance, long-term stability and effectiveness, service life of more than 50 years. 7. Under normal conditions, it is light black solid powder, non-toxic, odorless and pollution-free. The specific gravity of the dry powder is 0.85-0.95, and the fineness of the dry powder is less than 200 meshes. 8. Strong water absorption and thermal insulation performance can keep the soil around the electrode moist for a long time, which greatly reduces the contact resistance between the grounding electrode and the soil. 9. Good permeability, through the infiltration to the surrounding soil and rock crevices, forming a root network, forming a gently changing low resistance drop area around the grounding electrode. 10. The solidified resistance reducing agent is weakly alkaline, surrounds the electrode, has a compact structure, effectively prevents aerobic corrosion, protects the electrode, and prolongs the service life of the electrode. Amount of resistance reducing agent The economic dosage of the resistance reducing agent shall be determined according to different soils, and the laying thickness on the grounding body shall be between 5 and 15 CM Construction requirements for resistance reducing agent 1) Pre-construction inspection items and requirements: ① The resistance reducing agent shall be the product of the same brand and model. ② The water is clear and free of pollution, and the water is free of sediment and other sundries. ③ The size and shape of the trench and hole shall meet the design requirements, the four walls shall be relatively flat, and there shall be no sundries in the hole and trench. ④ The vertical grounding electrode shall be placed in the center of the hole, and the horizontal grounding electrode shall be placed in the middle horizontally, and the distance from the trench bottom shall not be less than 40mm and shall be uniform (if necessary, it can be fixed with a thin wire). ⑤ The grounding downlead has been painted with antirust paint according to the design requirements and has been initially set. 2) adding water into the prepared resistance reducing agent according to the weight ratio of water to the resistance reducing agent of 0.4-0.6: 1.0, and fully stirring the mixture until the mixture is in a sticky state. The amount of water used for horizontal grounding is just enough to wet all the dry powder and stir it into paste. The water addition amount of the resistance reducing agent for the vertical grounding hole can be the higher value as the case may be. Excessive water addition will prolong the construction time. 3) Pouring, coating and preliminary inspection: gently pour the prepared pasty resistance reducing agent into the grounding trench and hole (to prevent debris and sundries from mixing into the resistance reducing agent) until the grounding electrode is completely coated without omission, and preliminarily measure that the coating thickness is not less than 40mm, the four walls of the borehole are full, and supplement if insufficient. 4) confirmatory test and backfill tamping. After the initial setting of the resistance reducing agent, carefully check that the resistance reducing agent coating surface is uniform, full and free of omission and impurities. The thinnest thickness of the coating body is not less than 40 mm. If it is insufficient, it should be supplemented with resistance reducing agent. After checking, remove the fixed thin line, gently backfill the fine soil without hard objects and branches, with a thickness of more than 200mm, and then add other soil and tamp it. The surface of the compacted backfill shall be slightly above the surrounding ground level. 5. Acceptance (1) During construction, the well depth shall conform to the design standard. (Construct according to the original design. If the design requirements are not met, the design shall be changed.) (2) Deep well grouting shall be fully filled without gaps, so as to better play the role of grounding electrode in reducing resistance. (3) The welding at the lap joint shall meet the requirements to ensure full welding without insufficient welding. And that weld spots are subject to anti-corrosion treatment to ensure the service life. 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Original title: The specifications of the drill bit are complete, and the arrangement is too complete. Drill is a tool used to drill through holes or blind holes in solid materials and to ream existing holes. The commonly used drill bits are twist drill, flat drill, center drill, deep hole drill and trepanning drill. It is customary to classify reamers and counterbores as drill bits, although they cannot make holes in solid material. M33.46.565136.5 M44.58.075188 M55.59.585229.5 M66.611.0902511 M89.014.01002812 M1011.017.51103012 M1214.020.01153212 1/46.8511.0902511 5/168.5514.01002812 3/810.115.01103012 1/213.520.01153212 Drill size 90 degree Specification Small diameter Large diameter Full length Small diameter Blade Long handle diameter M33.46.465356.4 M44.58.475428.4 M55.510.4855010.4 M66.612.5905312.0 M89.016.51005312.0 Specification table for center bit Blade diameter (d) Blade diameter tolerance Blade length (L2) Shank diameter (D) Overall length (L) 0.40.05-0.050.53.031 0.50.05-0.050.63.031 0.60.05-0.050.73.536 0.70.05-0.050.83.536 0.80.05-0.050.94.036 0.90.05-0.051.04.036 1.00.05-0.051.24.036 1.24.0100 1.20.05-0.051.45.042 1.50.05-0.051.85.042 1.85.0100 1.85.0150 1.85.0200 2.00.08-0.082.45.042 2.46.0100 2.46.0150 2.46.0200 2.50.08-0.083.06.047 3.08.0100 3.08.0150 3.08.0200 3.00.08-0.083.67.757 3.610.0100 3.610.0150 3.610.0200 3.20.08-0.083.87.757 4.00.08-0.084.810.069 4.810.0100 4.810.0150 4.810.0200 5.00.12-0.126.011.069 6.012.0100 6.012.0150 6.012.0200 6.00.12-0.128.016.090 8.00.12-0.1210.018.0100 10.00.12-0.1212.018.0100 12.00.12-0.1215.022.0110 High-speed steel hollow drill bit, also known as core drill bit or hole opener, drill bit classification: high-speed steel drill bit, hard alloy drill bit, tungsten steel drill bit; cutting depth: 35MM, 50MM, 100M; suitable for drilling machine: imported magnetic seat drill, magnetic drill, mining dth bit, domestic magnetic seat drill, magnet drill, magnet drill, steel plate drill, magnetic drill, overburden drilling systems, machine tool, bench drill, seat drill and so on Diameter specification: 12mm to 100mm; the main material of drill bit is high-speed steel. Powder metallurgy; Cemented carbide. The axis of the drill bit shall be inclined at an angle of 60 ° to the grinding wheel surface. This angle is the point angle of the drill. If the angle is not correct, it will directly affect the size of the point angle of the drill, the shape of the main cutting edge and the bevel of the chisel edge. This refers to the position relationship between the axial line of the drill bit and the surface of the grinding wheel. It is OK to take 60 °, which is generally more accurate. Attention shall be paid to the relative horizontal position and angle position of the drill before sharpening. The two positions shall be considered as a whole. Do not neglect to set the angle for the sake of setting the cutting edge, or neglect to set the cutting edge for the sake of setting the angle. The greater the ratio of the length to the diameter of the drill bit, the greater its tendency to bend. The bending force can be reduced by reducing the length-diameter ratio, thereby avoiding the breakage of the drill bit and the increase of the hole diameter error. Deeper holes require drill sizes with larger length to diameter ratios. Usually, a hole with a depth of more than three times the diameter is a "deep hole", DHD Drill bit , Borehole Drill Bits, and the depth of a micro-drill generally exceeds this limit. Specification of electric hammer bit: 6mm, 8mm X 110mm; 8mmx160mm; 8mm,10mm,12mmx210mm,10mm,12mm,16mm,20mmx450mm。 The main body of the hard alloy electric hammer drill is made of high-quality alloy steel, and the tool bit is welded with hard alloy. Used together with various electric hammers, suitable for drilling on hard building materials such as concrete, brick, etc. It is a widely used and highly efficient punching tool in the construction and installation industry. Specification of electric hammer bit set: 5110mm × 6 Specification of electric hammer bit set: 5110mm, 6110mm, 6160mm, 8160mm, 10160 mm Round shank and square shank of electric hammer bit 6MM 8MM 10MM 12MM 14MM 16MM-28MM is Through-wall drill length 350 MM 16MM 18MM 20MM 22MM 25MM 28MM Drill bit type A. Classification by structure (1) Integral drill bit: the drill top, the drill body and the drill shank are integrally made of the same material. (2) End welding type drill bit, the drill top part is welded by carbide. B. Classification by drill (1) Straight shank drill bit: the drill bit diameter is less than ψ 13.0. Below mm, straight shanks are used. (2) Taper shank drill bit: the shank of the drill bit is tapered, and generally its taper is Morse taper. C. Classified by use (1) Center drill bit: It is generally used to drill the center point before drilling. The front conical surface is 60 °, 75 °, 90 °, etc. In order to use the tailstock to support the lathe during operation, the 60 ° center drill bit should be matched with the lathe tailstock center at 60 °. (2) Twist drill bit: It is the most widely used drill bit in industrial manufacturing, and we generally use twist drill bit. (3) Superhard drill bit: The front end of the drill body or all of it is made of superhard alloy tool material, which is used for drilling and processing materials. (4) Oil hole drill bit: The drill body has two small holes through which the cutting agent reaches the cutting edge to take away heat and chips. With this drill bit, the workpiece is generally rotated while the drill bit is stationary. (5) Deep-hole drill bit: It was first used for the drilling of gun barrels and stone barrels, also known as gun barrel drill bit. The deep hole drill is of a straight flute type, and a quarter of a strong portion is cut off in a circular tube to produce chip removal at the cutting edge. (6) Drill bit reamer: In order to meet the needs of mass production, the front end is a drill bit and the rear end is a reamer. The diameter of the drill bit and the diameter of the reamer are only the margin of reaming. There are also drill bits used in combination with screw tapping, so they are also called mixed drill bits. (7) Taper drill: Taper drill can be used when machining the feed inlet of the mold. (8) Cylindrical hole drill: We call it a countersunk end mill. The front end of this kind of drill has a part with a smaller diameter, rock drilling tools, which is called the lead. (9) Taper hole drill: It is used for drilling taper holes. Its front end angle is 90 °, 60 °, etc. The chamfering cutter we use is a kind of taper hole drill. 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Original Title: [Collection] Encyclopedia of Common Exploration Techniques and Methods for Landslide This article is selected from the book "Technical Guidelines for Landslide Control". First published on the Wechat Public Number of the Voice of Natural Resources At present, the commonly used exploration techniques and methods of landslide mainly include engineering geological mapping, exploration (drilling, mountain engineering, geophysical exploration), sampling and testing, monitoring and so on. Landslide exploration should select appropriate exploration techniques and methods according to the nature and requirements of the problems to be identified. 5.1 Engineering geological mapping Engineering geological surveying and mapping is the basis of landslide exploration work such as drilling, mountain engineering and geophysical prospecting. It is carried out first in various exploration methods and is an important technical means in the preliminary and detailed exploration stages of landslide. The relevant requirements are as follows. 1) Landslide engineering geological surveying and mapping shall be carried out on the basis of making full use of remote sensing interpretation results and existing regional geological data. The scope of surveying and mapping shall include the landslide section and its adjacent areas. The rear part shall include a certain range of stable slopes or catchment depressions above the back wall of the landslide. The front part shall include stable sections below the shear outlet. Both sides shall reach a certain distance beyond the landslide or adjacent valleys. The wading landslide shall reach the water surface of the river (reservoir) or the opposite bank, which is generally controlled at 50 ~ 100m outside the landslide boundary. At the same time, it should include the scope of possible hazards and derived disasters. In some cases, it shall be widened longitudinally to the top of the slope, the shoulder of the valley, the valley bottom, lithology or slope and other important changes, and shall include groundwater outcrops and important geological structures horizontally. 2) In different stages of landslide exploration, the scale and accuracy requirements for engineering geological surveying and mapping are different, and the relevant technical requirements are also different. See the introduction in Chapter IV of this guide for the specific technical requirements of each stage. 3) The engineering geological surveying and mapping method adopts the comprehensive survey method, and the important geological phenomena such as boundary, crack, soft interlayer and shear outlet shall be traced. 4) In the covered or unobvious sections, there should be manual exposure points to ensure the accuracy of surveying and mapping and identify the main engineering geological problems. 5.2 Exploration Landslide exploration techniques mainly include drilling, mountain engineering (well exploration, trenching, tunnel exploration) and geophysical exploration. Exploration is an important part of landslide exploration work, and the workload and working method should be determined according to the complexity of geological conditions in the landslide area. The main task of landslide exploration is to find out the scope, thickness, material composition of the landslide mass, the number and shape of the sliding surface (zone) and the material composition of each sliding zone; basically find out the number, distribution, source and dynamics of groundwater aquifers in the landslide mass and the hydraulic connection of each aquifer. 5.2.1 Drilling Drilling is used to understand the internal composition and structure of geological hazard body, including the composition of rock and soil, the situation of sliding surface (zone), the situation of controlling structural plane of collapse dangerous rock and the state of groundwater, observe the deep displacement, and collect various rock and soil samples. The structure of the landslide body and the location and burial depth of the groundwater aquifer in the landslide body can be judged through the core collected by drilling, combined with the drilling speed, empty drilling, sticking, flushing fluid leakage and other phenomena in the drilling construction. The borehole can also be used for pumping test, water injection test, geophysical prospecting well, etc., to measure hydrogeological parameters such as groundwater level and water inflow, and to take water samples for water quality analysis and other hydrogeological work. Landslide exploration boreholes can also be used for long-term monitoring of landslide deep displacement and groundwater. Drilling is the most important and commonly used technical means for landslide exploration, and the workload should be determined according to the complexity of geological conditions in the landslide area and the technical requirements in the exploration stage. Expand the full text 5.2.1.1 Selection of drilling technology and method 1) The drilling method with small disturbance to the landslide stratum shall be selected as far as possible to improve the core recovery. 2) Dry drilling shall be adopted for cohesive soil, silty soil, artificial fill and sandy soil that is not easy to collapse above the groundwater level in the sliding mass. 3) The rock and soil layer below the underground water level in the sliding mass, as well as the sliding zone and the range of 5m above and below the sliding zone shall be drilled with drilling methods that have little disturbance to the rock and soil of the landslide, such as double-tube single-acting, double-tube double-acting, pump-free reverse circulation and other drilling methods. 5.2.1.2 New Drilling Technology for Landslide — — Air Dth Hammer Coring Drilling Technology with Casing Aiming at the technical problems of low core recovery, low drilling efficiency and drilling fluid leakage affecting formation stability in complex strata such as Quaternary accumulation strata, broken rock strata and landslide strata, the Institute of Exploration Technology, Chinese Academy of Geol ogical Sciences, adopts the principle of air drilling and combines the down-the-hole hammer drilling technology in the field of engineering drilling with the core drilling technology in the field of core drilling. By optimizing the design, a new drilling technology, air Dth hammer simultaneous casing coring drilling technology, dth rock bit, has been formed, which has the advantages of fast drilling speed, good coring quality and no effect on formation stability. GGQX series down-the-hole hammer and casing coring drilling tools and other core technology products have been developed, forming three product specifications of GGQX-168, GGQX-146 and GGQX-127. The technical features of the air Dth hammer coring and casing drilling technology are as follows: (1) Down-the-hole hammer and casing coring tool A. Drilling tool structure As shown in Fig. 5.1, the drilling tool is mainly composed of pneumatic impactor (down-the-hole hammer), center coring tool and casing shoe assembly. The former two are connected as a whole, which is the part that can be lifted and lowered with the drill pipe (for taking the core). The latter is attached to the casing string and remains in the hole to protect the wall. Figure 5.1 Down-the-hole Hammer Coring Tool B. Characteristics of drilling tools The drilling tool adopts the principle of synchronous and concentric casing drilling, and the casing following up with drilling isolates the hole wall in time, thus creating good coring drilling conditions. The stepped drilling principle of a center bit (lip surface) leading casing bit is adopted, and a high-pressure airflow channel is separated from a low-pressure channel, so that high-pressure airflow is directly exhausted from a high-pressure exhaust hole, and the high-pressure airflow is prevented from scouring the core at the bottom of the hole; and the core is forced to be extruded into the core tube, so that the high-quality core can be obtained. It not only has the advantages of fast drilling speed and good wall protection effect, but also has the ability to collect high-quality cores. The drilling tool has the advantages of simple structure, easy operation and good practicability. C. Drilling tool specification . Main technical parameters See Table 5.1 for drilling tool specifications and main technical parameters. Table 5.1 Main technical parameters of air Dth hammer simultaneous casing coring drilling tool (2) Supporting Dth hammer coring drilling tool As the drilling depth of the down-the-hole hammer and casing coring tool is generally not more than 40 m, in order to solve the drilling requirements of the hole depth greater than 40 m, and to deal with the drilling faults such as core shedding and a large number of cuttings precipitation that may occur during the drilling of the down-the-hole hammer and casing coring tool, the corresponding down-the- hole hammer coring tool is provided for the casing coring drill. A. Drilling tool structure As shown in Fig. 5.2, the Dth hammer coring tool belongs to the structural type of double-acting double-tube coring tool; it is mainly composed of upper joint 1, fastest dth hammer, anti-torque washers 2 and 8, O-rings 3 and 11, pin 4, inner tube joint 5, outer tube 6, inner tube 7, coring bit 9 and inner tube nipple 10. The upper connector 1 is directly connected to the air impactor. Fig. 5.2 Structure Diagram of Dth Hammer Coring Tool Corresponding to the down-hole hammer and casing coring drill, the down-hole hammer coring drill has three specifications, wherein, the Φ127 drilling tool is matched with the GGQX-168 drilling tool; the Φ108 drilling tool is matched with the GGQX-146 drilling tool; and the Φ89 drilling tool and the GGQX- 127 drilling tool. See Table 5.1 for drilling tool specifications and main technical parameters. B. Use (3) Brief introduction to the application of air Dth hammer simultaneous casing core drilling technology The Dth hammer simultaneous casing drilling technology has been tested and applied in the exploration projects of Jialin Village Landslide in Changdu County, Xiatong Street Landslide in Changdu Town, Luding Bridge Power Station in Dadu River, Southern Suburb Water Plant in Xigaze, and K284 + 798 ~ K284 + 854 Section of Mianguang Road in Tibet, and good results of simultaneous casing drilling technology have been achieved. The core recovery is more than 90%, the drilling speed is more than 2.5m/m, and the comprehensive drilling efficiency is improved by more than 100% compared with the conventional method. Fig. 5.3 shows the slip zone core taken by down-the-hole hammer simultaneous casing coring drilling, and Fig. 5.4 shows the core taken in the riverbed accumulation formation. Fig. 5.3 Sliding zone core taken in down-the-hole hammer simultaneous casing coring drilling Fig. 5.4 Core of riverbed accumulation layer taken by down-the-hole hammer simultaneous casing coring drilling 5.2.2 Mountain engineering Mountainous engineering includes trenching, well exploration, tunnel exploration, etc. See Table 5.2 for the purpose and use conditions of various mountainous engineering, which can be selected according to the geological conditions of landslide and the technical requirements of exploration stage. Table 5.2 Brief Table of Suitability of Landslide Exploration for Mountain Engineering (1) Trenching Trenching is a simple shallow excavation project, and the excavation depth is generally not more than 5m. Simple excavation tools can be used. According to the type of rock and soil mass and the depth of the trench, slope excavation can be carried out with reference to the excavation regulations of the slope rate method. When the soft stratum and the exploratory trench are deep, temporary protective measures such as wood plate and steel pipe support shall be taken. Trenches that are no longer used after exploration shall be backfilled to restore the original ground. (2) Well exploration The construction depth of the exploratory well for landslide exploration can reach 20 m, which is mainly used to find out the structure of the complex landslide with medium or above and deep sliding surface, collect the undisturbed soil samples of the sliding zone, and conduct large-scale shear tests in the well. Shaft is generally used for well exploration. Due to the large amount of earthwork excavation, professional excavation, muck lifting and other machinery and equipment are required. The construction safety requirements are high, and special support is required for the shaft wall. The vertical shaft formed by excavation can be used as a catchment well for subsequent landslide control and drainage works and a monitoring well for hydrogeological dynamic changes. Unused exploratory wells shall generally be backfilled to restore the original ground. (3) Adit exploration Adit exploration is one of the large-scale exploration projects used to identify deep landslide or complex landslide. Adit exploration is generally horizontal tunnel engineering. The portal is mainly selected at the front or rear edge of the landslide, and the horizontal tunnel passes through to a certain depth near or below the sliding bed. It is mainly used to find out the structure of the complex landslide, especially the location of the sliding zone (or weak structural plane), and to collect the undisturbed soil samples of the sliding zone for large-scale shear test in the tunnel. The section of the tunnel body of the adit exploration mostly adopts the arched tunnel of the city gate, which is generally 1.8 m high and 1.5 m wide. The excavation of earthwork and stonework for adit-exploration construction is large, which requires a professional tunnel construction team to use drilling and blasting excavation, muck transfer and other machinery and equipment, which requires high construction safety, and requires special support for the roof and wall of the tunnel. The portal shall be provided with a pilot tunnel, mining dth bit , dhd drill bit, and the slope at the top of the tunnel shall be protected. The tunnels formed by excavation are generally used as drainage tunnels for subsequent landslide control projects. 5.2.3 Geophysical Prospecting The main task of geophysical prospecting for landslide is to delineate the spatial distribution boundary of landslide body, detect the water content of landslide area, detect the number, depth and shape change of structural plane and sliding plane, and detect the stratigraphic structure, concealed boundary and concealed geological body of landslide body. (1) Geophysical methods commonly used in landslide exploration Geophysical methods commonly used in landslide exploration and their application conditions and technical and economic characteristics are shown in Table 5.3. Table 5.3 Brief Table of Suitability of Geophysical Prospecting Methods for Landslide (2) Selection principle of geophysical prospecting method for landslide In order to give full play to the role of geophysical exploration techniques and methods in geological hazard exploration, the following selection principles should be considered in the selection of specific methods and means. (3) Optimized combination of geophysical prospecting methods for landslide According to the Code for Investigation of Landslide Control Engineering (GB/T32864 — 2016), the recommended optimization combination method of landslide geophysical exploration methods is shown in Table 5.4. Table 5.4 Optimized Combination of Geophysical Methods for Landslide Note: ∗ Available methods; ∗ ∗ Common methods; ∗ The preferred method. 5.3 Sampling and testing In the process of landslide exploration, rock, soil, groundwater and other samples should be systematically taken for analysis and identification to obtain the necessary parameters. The test work mainly includes field test and indoor test, which are generally carried out in coordination. The test content is to meet the needs of landslide stability evaluation and control engineering design. The test objects shall include sliding mass, sliding zone, sliding bed rock and soil mass and groundwater; the main test contents include physical properties, mechanical properties, groundwater composition and corrosiveness, rock and soil chemical composition, mineral composition, microstructure and other analysis, which shall be carried out according to specific needs. (1) Hydrogeological in-situ test The main purpose of hydrogeological in-situ test is to understand the state of landslide aquifer and the permeability coefficient of soil layer. Test methods include borehole water injection test, borehole pumping test and test pit water injection test. If there is groundwater in the landslide mass, pumping test shall be carried out. If the amount of groundwater in the landslide mass is small, simple pumping test (lifting barrel pumping) can be used. If the amount of groundwater in the slope mass is large, a maximum drawdown pumping test shall be carried out, and the stability time shall be 4 ~ 8 H. If there are multiple aquifers in the slope mass, stratified pumping test should be carried out. When the landslide mass is above the groundwater level, the water injection test should be adopted. When the composition and structure (permeability) of the rock (soil) mass in the vertical direction are quite different, the layered water injection test should be carried out. (2) Geotechnical field test The geotechnical field test includes the in-situ large-area direct shear test of the sliding zone soil and the large-volume gravity test of the sliding zone soil and the sliding mass soil. Before the shear test, the saturated state and material composition of the specimen shall be described; after the test, the characteristics of the shear plane shall be described, the shear angle and actual shear area shall be measured, and the shear results shall be corrected. Volumetric method should be used for bulk density. The volume of test pit should be determined according to the composition and particle size of soil, and the volume can be measured by water injection. (3) Rock and soil indoor test The geotechnical laboratory test shall comply with the provisions of Standard for Engineering Rock Mass Test Method (GB/T50266 — 2013) and Standard for Soil Test Method (GB/T50123 — 1999). Indoor triaxial compression test should be carried out for the soil with potential sliding zone without sliding surface. When the test conditions are not available and the effective stress intensity index is required, the slow shear test can be used. Refer to Table 5.5 for the contents of indoor test of geotechnical analysis. Table 5.5 List of Indoor Test Items for Physical and Mechanical Properties of Rock and Soil Note: √ indicates the test to be conducted, indicating the test to be conducted as required; water quality analysis shall be determined as required; rock and soil samples for indoor test shall be taken in accordance with JGJ/89-92 Technical Standard for Sampling of Undisturbed Samples. 5.4 Monitoring Dynamic observation and monitoring of landslides include long-term observation of displacement and observation of groundwater in landslides. The purpose of observation and monitoring is to analyze the formation mechanism, activity state and development trend of landslides. For some landslides, especially the bedding landslides, the monitoring data are also helpful to analyze the spatial distribution characteristics of the sliding surface. Through observation and monitoring, we can grasp the moving process of the landslide, determine the time when the landslide reaches the maximum moving speed and the state of the landslide, so as to analyze and predict the future development trend of the landslide. Landslide monitoring mainly includes surface deformation monitoring, crack monitoring, building deformation monitoring, sliding surface displacement monitoring, groundwater level monitoring, soil moisture detection, etc; If adit and shaft are arranged for exploration, it is advisable to monitor the displacement of the mouth of the adit (shaft), the displacement of the sliding zone in the adit (shaft), the change of crack convergence and the displacement dislocation. The specific technical methods and selection methods of landslide monitoring are shown in Part VI of this Guide. 5.5 Application cases of exploration technologies and methods The exploration techniques and methods shall be reasonably selected according to the geological environment conditions of the landslide, the technical requirements of the exploration stage and the exploration construction conditions, so as to find out the type, structure, scope, shape and other characteristics of the landslide and obtain reasonable physical and mechanical parameters. The following is an introduction to the practical application of various exploration techniques and methods by taking the landslide exploration in Jianshe Street, Danba, Sichuan as an example. Jianshe Street Landslide in Danba County, Sichuan Province is an ancient landslide located in the southwest of Danba County. Since 2003, the landslide began to revive gradually, and the deformation intensified in December 2004, so the engineering treatment must be carried out, so the landslide exploration work was carried out. The landslide is a large accumulation landslide, and the landslide area is mainly composed of loose ancient landslide deposits. The plane of the landslide body is in the shape of a ring chair, with an elevation of 1881-2110m and a height difference of 223m between the front and rear edges. The front edge of the landslide reaches Jianshe Street in Danba County. The landslide mass is 200 ~ 250 m wide, 290 m long, 0.08 km2 in area, 30 m in average thickness and 2200 × 104 m3 in volume. The front part of the landslide is a 6 ~ 28 m high dry block stone slope protection scarp built after artificial excavation, with a slope of 56 ° ~ 65 °. The average slope of the middle part is 31 °, and the rear part is a gentle slope section with a slope of about 10 °. According to the deformation development process, genetic mechanism and sliding characteristics of the landslide mass, the landslide area is divided into three areas: the main sliding area (including two subareas I-1 and I-2), the left rear traction area (II) and the right rear traction area (III) (Fig. 5.5 and Fig. 5.6). Figure 5.5 Landslide behind Jianshe Street, Danba, Sichuan Fig. 5.6 Plan of Landslide behind Jianshe Street in Danba, Sichuan According to the geological environmental conditions of the landslide, on the basis of the measured 1:500 topographic map, the comprehensive exploration was carried out by using the technical methods of engineering geological mapping, geophysical exploration, drilling, trenching, field and indoor tests, and landslide dynamic monitoring. The application of each exploration technology and method is as follows. (1) Engineering geological mapping The engineering geological mapping of the landslide area and a certain range of peripheral slope sections has been carried out, covering an area of 0.342 km 2. Through engineering geological surveying and mapping, the external shape, elements and deformation characteristics of the landslide are identified, which provides the basis for geophysical exploration, drilling and trenching, and monitoring. (2) Geophysical prospecting According to the characteristics of the accumulation layer landslide of Jianshe Street landslide, the high and steep terrain, and the difficulty of heavy exploration work such as drilling and mountain engineering, the application of geophysical exploration methods is strengthened in exploration technology and methods. High-density electrical method and electrical sounding method are used in geophysical prospecting. 15 (scale 1:500) geophysical profiles totaling 4.9 km and 3 (scale 1:200) geophysical profiles totaling 3.5 km are arranged, and 970 high-density electrical survey points and 18 electrical sounding survey points are set. Wenner device is selected for high-density electrical method, and the electrode spacing is 5m. The number of electrodes is 60 and the supply voltage is 180 V. Symmetrical quadrupole device is used for electrical sounding, the minimum AB/2 is 1.4m, the maximum is 115m, MN/2 is 1m, and the power supply voltage is 180V. Through geophysical prospecting, drilling and engineering geological mapping, the thickness of the sliding mass in the landslide area and the undulation and burial depth of the underlying bedrock are basically ascertained. (3) Drilling According to the armchair landform characteristics of the landslide and the distribution of cracks, one longitudinal main exploration line and two auxiliary exploration lines are arranged along the main sliding direction, and one main exploration line and two auxiliary exploration lines are arranged horizontally. Seven boreholes are arranged at the intersection of the exploration line, with a total footage of 318 m and an average hole depth of 45 m. In the later stage, 7 supplementary exploration boreholes were arranged according to the needs of the treatment project. The main exploration profile is shown in Figure 5.7. Fig. 5.7 Longitudinal Section of Landslide at the Back of Jianshe Street in Danba, Sichuan Full-hole coring is adopted for drilling, and vegetable glue hole protection or casing drilling technology is adopted for the overburden, so that the core recovery rate of the landslide body reaches more than 80%. The drilling identified the thickness of the landslide, the location and shape of the sliding surface, the depth of groundwater and the nature of the underlying rock and soil mass of the sliding surface, which provided basic geological data for the calculation of landslide stability and the judgment of its development trend. (4) Mountain engineering Trenching was used in mountain engineering, and four trenches were set at the cracks at the rear edge of the landslide to understand the contact relationship between different rock and soil masses and the tensile cracks, and sampling tests were carried out. (5) Field and indoor tests Soil sample: the landslide mass is mainly composed of block stone and soil, and it is difficult to obtain the soil sample, so only one group of soil sample is taken from ZK4 borehole for indoor routine test. In combination with the trench excavation work at different locations on the sliding mass, 6 groups of heavy gravity tests were completed. Rock samples: 8 groups of samples were taken from each borehole for laboratory tests, and the physical and mechanical data of rocks were obtained for the design of landslide control. (6) Landslide dynamic monitoring In order to fully grasp the landslide deformation activities, since January 21, 2005, 46 professional monitoring points (total station monitoring) and 26 simple artificial monitoring points have been gradually set up on the landslide mass according to the landslide activity conditions, and special personnel have been assigned to conduct manual inspection on various deformation and failure signs of the slope mass. At the same time, three deep displacement monitoring holes are arranged on the main exploration line of the landslide, Mining Drilling Equipment, and the deep displacement of the landslide is monitored in real time by the borehole inclinometer. Abundant surface and deep displacement monitoring information provides an important basis for landslide stability analysis and information design and construction of control engineering. This article is selected from Technical Guidelines for Landslide Prevention and Control (Yin Yueping et al., Geological Publishing House, 2018). Return to Sohu to see more Responsible Editor:. wt-dthtools.com
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Original Title: [Collection] Encyclopedia of Common Exploration Techniques and Methods for Landslide This article is selected from the book "Technical Guidelines for Landslide Control". First published on the Wechat Public Number of the Voice of Natural Resources At present, the commonly used exploration techniques and methods of landslide mainly include engineering geological mapping, exploration (drilling, mountain engineering, geophysical exploration), sampling and testing, monitoring and so on. Landslide exploration should select appropriate exploration techniques and methods according to the nature and requirements of the problems to be identified. 5.1 Engineering geological mapping Engineering geological surveying and mapping is the basis of landslide exploration work such as drilling, mountain engineering and geophysical prospecting. It is carried out first in various exploration methods and is an important technical means in the preliminary and detailed exploration stages of landslide. The relevant requirements are as follows. 1) Landslide engineering geological surveying and mapping shall be carried out on the basis of making full use of remote sensing interpretation results and existing regional geological data. The scope of surveying and mapping shall include the landslide section and its adjacent areas. The rear part shall include a certain range of stable slopes or catchment depressions above the back wall of the landslide. The front part shall include stable sections below the shear outlet. Both sides shall reach a certain distance beyond the landslide or adjacent valleys. The wading landslide shall reach the water surface of the river (reservoir) or the opposite bank, which is generally controlled at 50 ~ 100m outside the landslide boundary. At the same time, it should include the scope of possible hazards and derived disasters. In some cases, it shall be widened longitudinally to the top of the slope, the shoulder of the valley, the valley bottom, lithology or slope and other important changes, and shall include groundwater outcrops and important geological structures horizontally. 2) In different stages of landslide exploration, the scale and accuracy requirements for engineering geological surveying and mapping are different, and the relevant technical requirements are also different. See the introduction in Chapter IV of this guide for the specific technical requirements of each stage. 3) The engineering geological surveying and mapping method adopts the comprehensive survey method, and the important geological phenomena such as boundary, crack, soft interlayer and shear outlet shall be traced. 4) In the covered or unobvious sections, there should be manual exposure points to ensure the accuracy of surveying and mapping and identify the main engineering geological problems. 5.2 Exploration Landslide exploration techniques mainly include drilling, mountain engineering (well exploration, trenching, tunnel exploration) and geophysical exploration. Exploration is an important part of landslide exploration work, and the workload and working method should be determined according to the complexity of geological conditions in the landslide area. The main task of landslide exploration is to find out the scope, thickness, material composition of the landslide mass, the number and shape of the sliding surface (zone) and the material composition of each sliding zone; basically find out the number, distribution, source and dynamics of groundwater aquifers in the landslide mass and the hydraulic connection of each aquifer. 5.2.1 Drilling Drilling is used to understand the internal composition and structure of geological hazard body, including the composition of rock and soil, the situation of sliding surface (zone), the situation of controlling structural plane of collapse dangerous rock and the state of groundwater, observe the deep displacement, and collect various rock and soil samples. The structure of the landslide body and the location and burial depth of the groundwater aquifer in the landslide body can be judged through the core collected by drilling, combined with the drilling speed, empty drilling, sticking, flushing fluid leakage and other phenomena in the drilling construction. The borehole can also be used for pumping test, water injection test, geophysical prospecting well, etc., to measure hydrogeological parameters such as groundwater level and water inflow, and to take water samples for water quality analysis and other hydrogeological work. Landslide exploration boreholes can also be used for long-term monitoring of landslide deep displacement and groundwater. Drilling is the most important and commonly used technical means for landslide exploration, and the workload should be determined according to the complexity of geological conditions in the landslide area and the technical requirements in the exploration stage. Expand the full text 5.2.1.1 Selection of drilling technology and method 1) The drilling method with small disturbance to the landslide stratum shall be selected as far as possible to improve the core recovery. 2) Dry drilling shall be adopted for cohesive soil, silty soil, artificial fill and sandy soil that is not easy to collapse above the groundwater level in the sliding mass. 3) The rock and soil layer below the underground water level in the sliding mass, as well as the sliding zone and the range of 5m above and below the sliding zone shall be drilled with drilling methods that have little disturbance to the rock and soil of the landslide, such as double-tube single-acting, double-tube double-acting, pump-free reverse circulation and other drilling methods. 5.2.1.2 New Drilling Technology for Landslide — — Air Dth Hammer Coring Drilling Technology with Casing Aiming at the technical problems of low core recovery, low drilling efficiency and drilling fluid leakage affecting formation stability in complex strata such as Quaternary accumulation strata, broken rock strata and landslide strata, the Institute of Exploration Technology, Chinese Academy of Geol ogical Sciences, adopts the principle of air drilling and combines the down-the-hole hammer drilling technology in the field of engineering drilling with the core drilling technology in the field of core drilling. By optimizing the design, a new drilling technology, air Dth hammer simultaneous casing coring drilling technology, down the hole bit, has been formed, which has the advantages of fast drilling speed, good coring quality and no effect on formation stability. GGQX series down-the-hole hammer and casing coring drilling tools and other core technology products have been developed, forming three product specifications of GGQX-168, GGQX-146 and GGQX-127. The technical features of the air Dth hammer coring and casing drilling technology are as follows: (1) Down-the-hole hammer and casing coring tool A. Drilling tool structure As shown in Fig. 5.1, the drilling tool is mainly composed of pneumatic impactor (down-the-hole hammer), center coring tool and casing shoe assembly. The former two are connected as a whole, which is the part that can be lifted and lowered with the drill pipe (for taking the core). The latter is attached to the casing string and remains in the hole to protect the wall. Figure 5.1 Down-the-hole Hammer Coring Tool B. Characteristics of drilling tools The drilling tool adopts the principle of synchronous and concentric casing drilling, and the casing following up with drilling isolates the hole wall in time, thus creating good coring drilling conditions. The stepped drilling principle of a center bit (lip surface) leading casing bit is adopted, and a high-pressure airflow channel is separated from a low-pressure channel, so that high-pressure airflow is directly exhausted from a high-pressure exhaust hole, and the high-pressure airflow is prevented from scouring the core at the bottom of the hole; and the core is forced to be extruded into the core tube, so that the high-quality core can be obtained. It not only has the advantages of fast drilling speed and good wall protection effect, but also has the ability to collect high-quality cores. The drilling tool has the advantages of simple structure, easy operation and good practicability. C. Drilling tool specification . Main technical parameters See Table 5.1 for drilling tool specifications and main technical parameters. Table 5.1 Main technical parameters of air Dth hammer simultaneous casing coring drilling tool (2) Supporting Dth hammer coring drilling tool As the drilling depth of the down-the-hole hammer and casing coring tool is generally not more than 40 m, in order to solve the drilling requirements of the hole depth greater than 40 m, and to deal with the drilling faults such as core shedding and a large number of cuttings precipitation that may occur during the drilling of the down-the-hole hammer and casing coring tool, the corresponding down-the- hole hammer coring tool is provided for the casing coring drill. A. Drilling tool structure As shown in Fig. 5.2, the Dth hammer coring tool belongs to the structural type of double-acting double-tube coring tool; it is mainly composed of upper joint 1, dth button bits, anti-torque washers 2 and 8, O-rings 3 and 11, pin 4, inner tube joint 5, outer tube 6, inner tube 7, coring bit 9 and inner tube nipple 10. The upper connector 1 is directly connected to the air impactor. Fig. 5.2 Structure Diagram of Dth Hammer Coring Tool Corresponding to the down-hole hammer and casing coring drill, the down-hole hammer coring drill has three specifications, wherein, the Φ127 drilling tool is matched with the GGQX-168 drilling tool; the Φ108 drilling tool is matched with the GGQX-146 drilling tool; and the Φ89 drilling tool and the GGQX- 127 drilling tool. See Table 5.1 for drilling tool specifications and main technical parameters. B. Use (3) Brief introduction to the application of air Dth hammer simultaneous casing core drilling technology The Dth hammer simultaneous casing drilling technology has been tested and applied in the exploration projects of Jialin Village Landslide in Changdu County, Xiatong Street Landslide in Changdu Town, Luding Bridge Power Station in Dadu River, Southern Suburb Water Plant in Xigaze, and K284 + 798 ~ K284 + 854 Section of Mianguang Road in Tibet, and good results of simultaneous casing drilling technology have been achieved. The core recovery is more than 90%, the drilling speed is more than 2.5m/m, and the comprehensive drilling efficiency is improved by more than 100% compared with the conventional method. Fig. 5.3 shows the slip zone core taken by down-the-hole hammer simultaneous casing coring drilling, and Fig. 5.4 shows the core taken in the riverbed accumulation formation. Fig. 5.3 Sliding zone core taken in down-the-hole hammer simultaneous casing coring drilling Fig. 5.4 Core of riverbed accumulation layer taken by down-the-hole hammer simultaneous casing coring drilling 5.2.2 Mountain engineering Mountainous engineering includes trenching, well exploration, tunnel exploration, etc. See Table 5.2 for the purpose and use conditions of various mountainous engineering, which can be selected according to the geological conditions of landslide and the technical requirements of exploration stage. Table 5.2 Brief Table of Suitability of Landslide Exploration for Mountain Engineering (1) Trenching Trenching is a simple shallow excavation project, and the excavation depth is generally not more than 5m. Simple excavation tools can be used. According to the type of rock and soil mass and the depth of the trench, slope excavation can be carried out with reference to the excavation regulations of the slope rate method. When the soft stratum and the exploratory trench are deep, temporary protective measures such as wood plate and steel pipe support shall be taken. Trenches that are no longer used after exploration shall be backfilled to restore the original ground. (2) Well exploration The construction depth of the exploratory well for landslide exploration can reach 20 m, which is mainly used to find out the structure of the complex landslide with medium or above and deep sliding surface, collect the undisturbed soil samples of the sliding zone, and conduct large-scale shear tests in the well. Shaft is generally used for well exploration. Due to the large amount of earthwork excavation, professional excavation, muck lifting and other machinery and equipment are required. The construction safety requirements are high, and special support is required for the shaft wall. The vertical shaft formed by excavation can be used as a catchment well for subsequent landslide control and drainage works and a monitoring well for hydrogeological dynamic changes. Unused exploratory wells shall generally be backfilled to restore the original ground. (3) Adit exploration Adit exploration is one of the large-scale exploration projects used to identify deep landslide or complex landslide. Adit exploration is generally horizontal tunnel engineering. The portal is mainly selected at the front or rear edge of the landslide, and the horizontal tunnel passes through to a certain depth near or below the sliding bed. It is mainly used to find out the structure of the complex landslide, especially the location of the sliding zone (or weak structural plane), and to collect the undisturbed soil samples of the sliding zone for large-scale shear test in the tunnel. The section of the tunnel body of the adit exploration mostly adopts the arched tunnel of the city gate, which is generally 1.8 m high and 1.5 m wide. The excavation of earthwork and stonework for adit-exploration construction is large, which requires a professional tunnel construction team to use drilling and blasting excavation, muck transfer and other machinery and equipment, which requires high construction safety, and requires special support for the roof and wall of the tunnel. The portal shall be provided with a pilot tunnel, mining dth bit , dth drilling hammer, and the slope at the top of the tunnel shall be protected. The tunnels formed by excavation are generally used as drainage tunnels for subsequent landslide control projects. 5.2.3 Geophysical Prospecting The main task of geophysical prospecting for landslide is to delineate the spatial distribution boundary of landslide body, detect the water content of landslide area, detect the number, depth and shape change of structural plane and sliding plane, and detect the stratigraphic structure, concealed boundary and concealed geological body of landslide body. (1) Geophysical methods commonly used in landslide exploration Geophysical methods commonly used in landslide exploration and their application conditions and technical and economic characteristics are shown in Table 5.3. Table 5.3 Brief Table of Suitability of Geophysical Prospecting Methods for Landslide (2) Selection principle of geophysical prospecting method for landslide In order to give full play to the role of geophysical exploration techniques and methods in geological hazard exploration, the following selection principles should be considered in the selection of specific methods and means. (3) Optimized combination of geophysical prospecting methods for landslide According to the Code for Investigation of Landslide Control Engineering (GB/T32864 — 2016), the recommended optimization combination method of landslide geophysical exploration methods is shown in Table 5.4. Table 5.4 Optimized Combination of Geophysical Methods for Landslide Note: ∗ Available methods; ∗ ∗ Common methods; ∗ The preferred method. 5.3 Sampling and testing In the process of landslide exploration, rock, soil, groundwater and other samples should be systematically taken for analysis and identification to obtain the necessary parameters. The test work mainly includes field test and indoor test, which are generally carried out in coordination. The test content is to meet the needs of landslide stability evaluation and control engineering design. The test objects shall include sliding mass, sliding zone, sliding bed rock and soil mass and groundwater; the main test contents include physical properties, mechanical properties, groundwater composition and corrosiveness, rock and soil chemical composition, mineral composition, microstructure and other analysis, which shall be carried out according to specific needs. (1) Hydrogeological in-situ test The main purpose of hydrogeological in-situ test is to understand the state of landslide aquifer and the permeability coefficient of soil layer. Test methods include borehole water injection test, borehole pumping test and test pit water injection test. If there is groundwater in the landslide mass, pumping test shall be carried out. If the amount of groundwater in the landslide mass is small, simple pumping test (lifting barrel pumping) can be used. If the amount of groundwater in the slope mass is large, a maximum drawdown pumping test shall be carried out, and the stability time shall be 4 ~ 8 H. If there are multiple aquifers in the slope mass, stratified pumping test should be carried out. When the landslide mass is above the groundwater level, the water injection test should be adopted. When the composition and structure (permeability) of the rock (soil) mass in the vertical direction are quite different, the layered water injection test should be carried out. (2) Geotechnical field test The geotechnical field test includes the in-situ large-area direct shear test of the sliding zone soil and the large-volume gravity test of the sliding zone soil and the sliding mass soil. Before the shear test, the saturated state and material composition of the specimen shall be described; after the test, the characteristics of the shear plane shall be described, the shear angle and actual shear area shall be measured, and the shear results shall be corrected. Volumetric method should be used for bulk density. The volume of test pit should be determined according to the composition and particle size of soil, and the volume can be measured by water injection. (3) Rock and soil indoor test The geotechnical laboratory test shall comply with the provisions of Standard for Engineering Rock Mass Test Method (GB/T50266 — 2013) and Standard for Soil Test Method (GB/T50123 — 1999). Indoor triaxial compression test should be carried out for the soil with potential sliding zone without sliding surface. When the test conditions are not available and the effective stress intensity index is required, the slow shear test can be used. Refer to Table 5.5 for the contents of indoor test of geotechnical analysis. Table 5.5 List of Indoor Test Items for Physical and Mechanical Properties of Rock and Soil Note: √ indicates the test to be conducted, indicating the test to be conducted as required; water quality analysis shall be determined as required; rock and soil samples for indoor test shall be taken in accordance with JGJ/89-92 Technical Standard for Sampling of Undisturbed Samples. 5.4 Monitoring Dynamic observation and monitoring of landslides include long-term observation of displacement and observation of groundwater in landslides. The purpose of observation and monitoring is to analyze the formation mechanism, activity state and development trend of landslides. For some landslides, especially the bedding landslides, the monitoring data are also helpful to analyze the spatial distribution characteristics of the sliding surface. Through observation and monitoring, we can grasp the moving process of the landslide, determine the time when the landslide reaches the maximum moving speed and the state of the landslide, so as to analyze and predict the future development trend of the landslide. Landslide monitoring mainly includes surface deformation monitoring, crack monitoring, building deformation monitoring, sliding surface displacement monitoring, groundwater level monitoring, soil moisture detection, etc; If adit and shaft are arranged for exploration, it is advisable to monitor the displacement of the mouth of the adit (shaft), the displacement of the sliding zone in the adit (shaft), the change of crack convergence and the displacement dislocation. The specific technical methods and selection methods of landslide monitoring are shown in Part VI of this Guide. 5.5 Application cases of exploration technologies and methods The exploration techniques and methods shall be reasonably selected according to the geological environment conditions of the landslide, the technical requirements of the exploration stage and the exploration construction conditions, so as to find out the type, structure, scope, shape and other characteristics of the landslide and obtain reasonable physical and mechanical parameters. The following is an introduction to the practical application of various exploration techniques and methods by taking the landslide exploration in Jianshe Street, Danba, Sichuan as an example. Jianshe Street Landslide in Danba County, Sichuan Province is an ancient landslide located in the southwest of Danba County. Since 2003, the landslide began to revive gradually, and the deformation intensified in December 2004, so the engineering treatment must be carried out, so the landslide exploration work was carried out. The landslide is a large accumulation landslide, and the landslide area is mainly composed of loose ancient landslide deposits. The plane of the landslide body is in the shape of a ring chair, with an elevation of 1881-2110m and a height difference of 223m between the front and rear edges. The front edge of the landslide reaches Jianshe Street in Danba County. The landslide mass is 200 ~ 250 m wide, 290 m long, 0.08 km2 in area, 30 m in average thickness and 2200 × 104 m3 in volume. The front part of the landslide is a 6 ~ 28 m high dry block stone slope protection scarp built after artificial excavation, with a slope of 56 ° ~ 65 °. The average slope of the middle part is 31 °, and the rear part is a gentle slope section with a slope of about 10 °. According to the deformation development process, genetic mechanism and sliding characteristics of the landslide mass, the landslide area is divided into three areas: the main sliding area (including two subareas I-1 and I-2), the left rear traction area (II) and the right rear traction area (III) (Fig. 5.5 and Fig. 5.6). Figure 5.5 Landslide behind Jianshe Street, Danba, Sichuan Fig. 5.6 Plan of Landslide behind Jianshe Street in Danba, Sichuan According to the geological environmental conditions of the landslide, on the basis of the measured 1:500 topographic map, the comprehensive exploration was carried out by using the technical methods of engineering geological mapping, geophysical exploration, drilling, trenching, field and indoor tests, and landslide dynamic monitoring. The application of each exploration technology and method is as follows. (1) Engineering geological mapping The engineering geological mapping of the landslide area and a certain range of peripheral slope sections has been carried out, covering an area of 0.342 km 2. Through engineering geological surveying and mapping, the external shape, elements and deformation characteristics of the landslide are identified, which provides the basis for geophysical exploration, drilling and trenching, and monitoring. (2) Geophysical prospecting According to the characteristics of the accumulation layer landslide of Jianshe Street landslide, the high and steep terrain, and the difficulty of heavy exploration work such as drilling and mountain engineering, the application of geophysical exploration methods is strengthened in exploration technology and methods. High-density electrical method and electrical sounding method are used in geophysical prospecting. 15 (scale 1:500) geophysical profiles totaling 4.9 km and 3 (scale 1:200) geophysical profiles totaling 3.5 km are arranged, and 970 high-density electrical survey points and 18 electrical sounding survey points are set. Wenner device is selected for high-density electrical method, and the electrode spacing is 5m. The number of electrodes is 60 and the supply voltage is 180 V. Symmetrical quadrupole device is used for electrical sounding, the minimum AB/2 is 1.4m, the maximum is 115m, MN/2 is 1m, and the power supply voltage is 180V. Through geophysical prospecting, drilling and engineering geological mapping, the thickness of the sliding mass in the landslide area and the undulation and burial depth of the underlying bedrock are basically ascertained. (3) Drilling According to the armchair landform characteristics of the landslide and the distribution of cracks, one longitudinal main exploration line and two auxiliary exploration lines are arranged along the main sliding direction, and one main exploration line and two auxiliary exploration lines are arranged horizontally. Seven boreholes are arranged at the intersection of the exploration line, with a total footage of 318 m and an average hole depth of 45 m. In the later stage, 7 supplementary exploration boreholes were arranged according to the needs of the treatment project. The main exploration profile is shown in Figure 5.7. Fig. 5.7 Longitudinal Section of Landslide at the Back of Jianshe Street in Danba, Sichuan Full-hole coring is adopted for drilling, and vegetable glue hole protection or casing drilling technology is adopted for the overburden, so that the core recovery rate of the landslide body reaches more than 80%. The drilling identified the thickness of the landslide, the location and shape of the sliding surface, the depth of groundwater and the nature of the underlying rock and soil mass of the sliding surface, which provided basic geological data for the calculation of landslide stability and the judgment of its development trend. (4) Mountain engineering Trenching was used in mountain engineering, and four trenches were set at the cracks at the rear edge of the landslide to understand the contact relationship between different rock and soil masses and the tensile cracks, and sampling tests were carried out. (5) Field and indoor tests Soil sample: the landslide mass is mainly composed of block stone and soil, and it is difficult to obtain the soil sample, so only one group of soil sample is taken from ZK4 borehole for indoor routine test. In combination with the trench excavation work at different locations on the sliding mass, 6 groups of heavy gravity tests were completed. Rock samples: 8 groups of samples were taken from each borehole for laboratory tests, and the physical and mechanical data of rocks were obtained for the design of landslide control. (6) Landslide dynamic monitoring In order to fully grasp the landslide deformation activities, since January 21, 2005, 46 professional monitoring points (total station monitoring) and 26 simple artificial monitoring points have been gradually set up on the landslide mass according to the landslide activity conditions, and special personnel have been assigned to conduct manual inspection on various deformation and failure signs of the slope mass. At the same time, three deep displacement monitoring holes are arranged on the main exploration line of the landslide, mining drill bit, and the deep displacement of the landslide is monitored in real time by the borehole inclinometer. Abundant surface and deep displacement monitoring information provides an important basis for landslide stability analysis and information design and construction of control engineering. This article is selected from Technical Guidelines for Landslide Prevention and Control (Yin Yueping et al., Geological Publishing House, 2018). Return to Sohu to see more Responsible Editor:. wt-dthtools.com
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Original Title: Instrument Plus | Instrument Introduction: Nucleic Acid Extraction and Purification Introduction of Nucleic Acid Extraction and Purification Nucleic acid is one of the most basic substances of life, which can be divided into DNA and RNA, and widely exists in all living organisms such as animals, plant cells, microorganisms and so on. It not only plays a role in storing and transmitting genetic information, but also plays an important role in protein biosynthesis, thus playing a decisive role in a series of important life phenomena such as growth, heredity and variation. Nucleic acid extraction includes DNA extraction, RNA extraction and plasmid extraction. Nucleic acid is the carrier of genetic information, the material basis of gene expression, and the main object of molecular biology research. To study the structure and function of nucleic acid, it is necessary to extract and purify the nucleic acid. The nucleic acid extractor is an instrument that uses the supporting nucleic acid extraction reagents to automatically complete the extraction of sample nucleic acid. The nucleic acid extractor is divided into two types: one is a large automatic, generally called automatic liquid workstation; the other is a small automatic nucleic acid extractor, which uses the packaged supporting reagents to automatically complete the extraction and purification process. Large automatic liquid workstations are rarely used because of the high cost of equipment and operation, and they are suitable for extracting thousands of the same kind of specimens at a time; while small automatic instruments are more and more used because of the low cost of equipment and operation and the convenience of operation. Method for extracting and purifying nucleic acid Since nucleic acid was first discovered in 1869, many researchers have made unremitting efforts to explore the extraction methods of nucleic acid, improved various materials and reagents of nucleic acid, and various reagents such as sodium dodecyl sulfonate, phenol, urea and guanidine salt have been applied to nucleic acid extraction experiments, and various commercial kits for nucleic acid extraction have emerged as the times require. The traditional extraction methods include phenol extraction, alkaline lysis, CTAB extraction and EtBr-CsCl gradient centrifugation. These traditional extraction methods can separate DNA and RNA from different tissue samples, but these techniques include precipitation and centrifugation steps, which require a large amount of biological samples, and the extraction steps are more complex, time-consuming and laborious, the yield is not high, it is difficult to achieve automatic operation, in addition, most of the traditional methods also need to use toxic chemical reagents. Therefore, with the development of molecular biology and polymer materials science, the traditional technology of separating nucleic acid from liquid phase system is gradually replaced by the new method based on solid phase carrier. Solid phase carrier adsorption method: The new nucleic acid extraction methods based on solid phase adsorbate carrier mainly include: centrifugal column extraction method, glass bead adsorption method, silica matrix method, anion exchange method and nano-magnetic bead extraction method. The operation steps of this kind of method can be divided into three parts: (1) promoting cell rupture by using a lysis solution to release nucleic acid in a liquid phase; Expand the full text (2) the released nucleic acid is specifically combined on a specific carrier by utilizing the stronger affinity and adsorption force of the carrier to the nucleic acid, so that other impurities such as protein, polysaccharide, lipid and the like are still dissociated in a liquid phase and are removed along with the removal of supernatant, And (3) eluting the nucleic acid adsorbed on the carrier by adjusting the ionic strength and pH value of the eluent to obtain the purified nucleic acid. Among them, the DNA extraction kit by centrifugal column method is widely used in the market because of its low price and relatively convenient operation. However, with the increasing demand for DNA extraction, the shortcomings of DNA extraction by centrifugal column method have become increasingly prominent. The centrifugal column method has the unavoidable disadvantages of large sample demand, large loss and inability to deal with rare samples. At the same time, the centrifugal column method needs repeated centrifugation in the process of DNA extraction, which is not convenient for high-throughput and automatic operation, and is incompatible with the requirements of modern biological experiments. In order to meet the development needs of high-throughput, high-sensitivity and automated operation of modern molecular biology, the DNA extraction technology by magnetic beads was born in the 1990s. Its principle is that the surface of magnetic beads has specific active groups, which can bind specifically and reversibly with nucleic acid under specific conditions. At the same time, the magnetic response ability of magnetic beads is used. Can conveniently carry out directional movement and enrichment under the action of an external magnetic field so as to realize the separation and purification of nucleic acid. Advantages of nucleic acid extraction by magnetic beads DNA extraction by magnetic beads is a perfect combination of nanotechnology and biotechnology, which has incomparable advantages over other DNA extraction methods: 1. Sample demand is low A high concentration of nucleic acid can be achieved with a small amount of material; 2. The operation is simple and fast The whole operation process is basically divided into five steps (cracking, combining, washing, drying and eluting), the whole process does not need centrifugal operation, and most of the processes can be completed within 30 to 60 minutes; 3. The quality is stable and reliable The binding capacity of the free magnetic beads and the nucleic acid is larger, the purity of the nucleic acid is higher due to the specific binding, and the recovery amount of the nucleic acid can be adjusted by controlling the surface groups of the magnetic beads; 4. Fully automated operation The nucleic acid extraction instrument can realize automatic and high-throughput operation, and can realize the extraction of dozens or even hundreds of samples by starting with one key; 5. Safe, non-toxic and harmless The reagent does not contain toxic chemical reagents such as phenol and chloroform, which fully conforms to the modern environmental protection concept. Precautions for Nucleic Acid Extraction by Magnetic Bead Method The use of biological magnetic beads to extract nucleic acid is still a relatively new method of nucleic acid extraction in China. Compared with the traditional isoamyl alcohol extraction method and centrifugal column kit method, this method is still inadvertently understood by many people. In the process of using magnetic beads to purify nucleic acid, there are also some misunderstandings. 1. Mistake one : The more magnetic beads you use, the better the extraction Many teachers like to increase the amount of magnetic beads when the extraction effect is not good, thinking that more magnetic beads can absorb more nucleic acid, which has to be said to be undesirable. The main characteristic of magnetic beads is that they can be dispersed in liquid, and can also be separated from liquid in solid state under the action of external magnetic field. In any reagent system, the ratio of magnetic beads to liquid should have a certain threshold. If the ratio exceeds a certain threshold, too many magnetic beads will lose their dispersion characteristics because they can not be uniformly dispersed in liquid. The efficiency of the contact between the nucleic acid magnetic beads and the liquid cannot be sufficiently increased during the washing process. Excessive magnetic beads will also adsorb more impurities, which has a great impact on the effect of impurity removal. Even sometimes, too many magnetic beads will adsorb protease, lysozyme and other functional components that play a major role in the liquid system, resulting in low efficiency of the whole kit. In many cases, when the extraction effect is not good, reducing the use of magnetic beads is the best way to improve the extraction effect. Usually, the amount of reference magnetic beads given by the magnetic bead method kit is slightly excessive, so it is not necessary to increase the amount of magnetic beads to improve the adsorption efficiency. However, if it is determined that the extraction effect is not good due to insufficient amount of magnetic beads, it is possible to improve the extraction effect by increasing the dosage of magnetic beads within a certain range. Taking GNT-02 series magnetic beads as an example, when extracting constant samples (plant tissues, whole blood, etc.), the dosage is usually 10 UL/time; when extracting trace samples (such as serum free DNA, oral swabs, etc.), the dosage of magnetic beads is 15 ~ 20 UL/time. If you need to exceed this usage, you need to communicate with the technical engineer. 2. Mistake two The more reagents are used, the better the extraction effect is. The cracking effect is not good? Add more lysis solution. Washing effect is not good? Add more washing up liquid. This is the inertial thinking of many customers in the use of kits. However, for the magnetic bead method, every increase in the volume of a part of the liquid reduces the collision probability of more magnetic beads, and reducing the collision probability of magnetic beads will lead to a significant decline in the adsorption rate. Therefore, in many cases, although increasing the amount of lysis solution and washing solution can indeed play a role in enhancing lysis and washing, the core of magnetic bead extraction is the efficiency of magnetic bead adsorption of nucleic acid, which can not guarantee the efficiency of nucleic acid extraction, so simply increasing the amount of reagents used to improve the extraction effect may not be completely effective. For GNT-B02 whole blood genomic DNA kit, the amount of lysis solution should not exceed 400ul/time, and the amount of washing solution should not exceed 500ul/time. If an amplification system is required, the amount of magnetic beads and sample should be increased accordingly, and this amplification is not necessarily proportional. 3. Mistake three The more times of washing, the better the extraction effect. When there are too many impurities in the extracted nucleic acid, users will consider washing several times to obtain more pure nucleic acid. Increasing the number of times of washing is indeed conducive to purifying nucleic acid, but considering that each washing will lose a certain amount of nucleic acid and increase the possibility of nucleic acid cleavage and hydrolysis, it is generally appropriate to control the number of times of washing at 2 to 4 times. For GNT series kit, the washing times of single purification kit is 2 times, the washing times of plant and animal kit is 3 times, and the washing time of blood kit is 3-4 times. 4. Mistake four : The more samples taken, the better the extraction When the sample is not fresh enough or the nucleic acid content itself is very small, the nucleic acid extraction effect is often not good, many teachers will use the way of taking more samples to increase the amount of nucleic acid extraction. However, simply increasing the sample volume may sometimes introduce too many impurities, which will exceed the cracking capacity of the cracking solution and reduce the extraction efficiency. Therefore, it is not recommended to simply increase the sample volume to achieve the purpose of increasing the extraction volume. If the extraction volume is too low due to insufficient sample size, it is recommended to start the extraction after enrichment or concentration in the pretreatment. Or increasing the completeness of the cleavage to expose more nucleic acids is also a solution. 5. Mistake five If a certain kind of magnetic bead is good, it should work well in all tests. There are many kinds of magnetic beads, such as different particle size, different dispersion, different magnetic response time, different coating base matrix, different outer modified functional groups, different coating density and different arm length of functional groups, which will lead to different characteristics of magnetic beads. Therefore, different magnetic beads are suitable for different experiments and systems. Just like the same reagent for nucleic acid extraction, the formula is not exactly the same, cbd centrifugal extractor , thin film distillation, and the properties of magnetic beads used for nucleic acid extraction are not exactly the same. Some magnetic beads show higher adsorption efficiency in the extraction of normal nucleic acid, and some magnetic beads are more suitable for the extraction of trace nucleic acid. Some magnetic beads are suitable for acidic series of reagent systems, and some magnetic beads are suitable for alkaline series of reagent systems. Some magnetic beads have good magnetic response but fast sedimentation speed, which are more suitable for magnetic rod automatic extractors; some magnetic beads have slow sedimentation speed but long magnetic response time, which are more suitable for pipetting automatic extractors. Few magnetic beads can be applied to all experimental situations, except for the fixed kit, in most cases, the magnetic beads and reagent system need to be adjusted for a certain period of time. 6. Mistake six : Compared with a certain kit, the effect is not good, but the magnetic beads are not good. In the process of screening magnetic beads, many customers simply replace the same amount of magnetic beads under the mature reagent system to compare the effect of magnetic beads. In this way, it is easy to draw the conclusion that the effect of a certain magnetic bead is not good, but in fact, because the suitable system and dosage of different magnetic beads are different, it often needs to be adjusted to obtain better extraction effect. Nucleic acid extraction and purification core parameter Extraction principle, mechanical principle, extraction time, sample handling capacity, sample tube capacity, Tip head handling capacity, number of Tip heads, interface, instrument weight, instrument size Application field of nucleic acid extraction and purification In almost every laboratory, the separation and purification work related to biomolecules is very important and indispensable. However, it is still very difficult to purify multiple samples, not only need to choose the appropriate purification technology, but also the workload is particularly large, it is difficult to meet the current rapid development of high-throughput sample extraction and purification needs. TIANLONG NP968 magnetic bead extraction and purification system uses magnetic bead technology, which can operate 1-32 samples at the same time, and can be widely used in genomics, disease control and medical treatment, food safety, forensic identification and other fields. 1. Genomics The Tianlong NP968 magnetic bead extraction and purification system is very suitable for genomics research. No matter the source of the extracted sample is microorganism, animal, plant or virus, the TIANLONG whole blood genome DNA extraction kit, the white blood cell layer whole blood genome extraction kit and the animal tissue/cell genome DNA extraction kit which are specially optimized for the TIANLONG NP968 magnetic bead extraction and purification system are combined, DNA or RNA with sufficient quantity and purity can be rapidly purified. High-quality nucleic acids can meet the needs of various downstream applications (such as PCR/Real-time PCR, gene chip, Southern blot, Northern blot). 2、CDC Based on the rapid and high-throughput technology of Tianlong NP968 magnetic bead extraction and purification, it can be used to solve the rapid automatic disease surveillance system of 2009 H1N1 flu virus (Influenza A virus subtype H1N1), children's hand-foot-mouth disease, measles virus and so on, and improve the response ability to major epidemics. The TIANLONG virus DNA/RNA extraction kit can be efficiently used for extracting RNA from cotton swabs, serum and other samples, especially for low-copy complex samples. Enterovirus EV-71 isolate (FY04-R5-C1) with an original virus content of 7.5T CID50/100μl was diluted in a 10-fold gradient of 5 dilutions. Real-time PCR detection results of each 100 μl sample after RNA extraction by centrifugal column and TIANLONG NP968 magnetic bead extraction and purification system. (Source: Chinese Center for Disease Control and Prevention) 3. Molecular diagnosis of clinical samples The Tianlong NP968 magnetic bead extraction and purification system can rapidly process clinical samples with high throughput, and the extracted nucleic acid can be used for subsequent molecular diagnosis. Tianlong NP968 combined with Tianlong FFPE tissue genomic DNA extraction kit is also suitable for formalin-fixed paraffin-embedded (formalin-Fixed and Parrffin-Embedded, FFPE) tissue samples. 4. Animal husbandry and veterinary medicine Can efficiently and sensitively extract avian influenza virus, Newcastle disease virus, Classical swine fever virus, CSFV), bovine viral diarrhea virus (Bovine viral diarrhea virus), Coxiella burnetii, etc. 5. Application of forensic medicine For forensic work, the efficiency and stability of nucleic acid extraction are very important. Tianlong NP968 magnetic bead extraction and purification system can be used with special forensic sample nucleic acid extraction magnetic bead reagent to purify high-quality DNA from different sources including cigarette butts, hair roots, cartilage, nails, blood stains and other materials, with a maximum processing capacity of 32 samples per time. Frequently asked questions about nucleic acid extraction and purification Q1: After adding Buffer 3 to the extracted plasmid, what is the effect of increasing the centrifugation speed and time on the extracted product? A1: After the addition of Buffer 3, the increase of Lixin speed and centrifugation time is indeed conducive to more compact adherence of the precipitate, but at room temperature If the centrifugation time is too long, the temperature of the liquid will rise and the plasmid will be degraded. In general, it can be centrifuged at 4 ℃ and 12000 rpm 10min, or centrifuging at 12000 rpm for 3-4min at normal temperature. Q2: During the recovery of agarose gel, if the recovered DNA fragment is too short, how to deal with it? A2: If the recovered DNA fragment is less than 500 BP, in order to improve the recovery efficiency, the gel can be dissolved by adding gel solution Then, isopropyl alcohol of 1.5 times the volume of the gel piece was added, and the mixture was thoroughly inverted and mixed. Q3: When the agarose gel is recovered, how to deal with the abnormal color after the gel liquid sol? A3: After the gel solution is completely dissolved, the normal color should be light yellow. If the color changes to red or orange, adjust the pH of the solution by adding 5.mu.l of 5m NaAc (pH 5.2) to restore the color of the mixture to the normal light yellow color (if the pH is not adjusted, the recovery of DNA will be affected). Q4: How to determine the relationship between lysate volume and sample mass during genomic DNA extraction: A4: Theoretically, the larger the volume of the lysate and the less the amount of the sample, the better the quality of the extracted product. Therefore, the best ratio of the lysis solution volume to the sample mass should be explored and optimized before the experiment. The following recommended values for the amount of sample that can be lysed with only 1 ml of lysing solution are for reference only. Q5: When extracting genomic DNA, what methods can be used to improve the yield of the product? A5-1: Properly increase the ratio of lysis solution volume to sample mass. A5-2: The eluent is preheated to about 65 ℃ in advance. At the same time, the eluent should be carefully added to the middle part of the adsorption membrane when it is loaded on the column, and ensure that the liquid completely covers the membrane. A5-3: If the volume of the mixed solution after sample lysis is too large when it is loaded on the column, it needs to be loaded on the column in several times, and ensure that the amount of sample loaded each time does not exceed 700 μl. A5-4: Properly extend the homogenization and lysis time of the tissue. Q 6: The reason for the high A260/A280 ratio of the extracted product? A6: The A260/A280 ratio of the purified DNA is between 1.8 and 2.0. If there is a large amount of residual RNA in the sample, the A260/A280 ratio will be higher, and RNase A needs to be added during the extraction process (if RNase A is added during the extraction process according to the instructions, The possibility of reduced RNase activity is considered). Q7: Precautions for sample handling prior to blood genomic DNA extraction? A7-1: Human blood contains a large number of enzyme inhibitors that may interfere with downstream DNA analysis, as well as common anticoagulants such as interferon and EDTA. Therefore, there is a need for a method for isolating DNA from human blood that provides high quality DNA free of contaminants and enzyme inhibitors. A7-2: The red blood cells of mammals do not contain nucleic acid, but the content of red blood cells in the blood of healthy mammals is nearly 1000 times higher than that of white blood cells containing nucleic acid (including lymphocytes, monocytes, granulocytes, etc.). Therefore, removing red blood cells before extracting genomic DNA can improve the yield of DNA. The recommended method is as follows: A7-2-1: Selective lysis of red blood cells: Under the condition of hypotonic buffer solution, red blood cells will undergo early hypotonic shock and rapid rupture. A7-2-2: Ficoll density gradient centrifugation to recover monocytes (lymphocytes and monocytes) and remove erythrocytes (this method also removes granulocytes). A7-2-3: The whole blood is centrifuged at 3300 G for 10 min at room temperature. After centrifugation, it will be divided into three layers: the supernatant layer is plasmid, the middle layer is white blood cell layer, and the bottom layer contains concentrated red blood cells. A7-3: The red blood cells of birds, fish, and frogs contain nucleic acids, so they do not need to be processed. A7-4: Blood samples (including blood samples that have been treated to remove red blood cells) that can be efficiently lysed with a lysing solution and protease or proteinase K. A7-5: In addition to animal genomic DNA, viral and bacterial DNA can also be isolated from blood. Q8: When extracting total RNA, how to determine the relationship between lysate and sample size? A8: Theoretically, the greater the volume of the lysate and the less the amount of sample, the better the quality of the extracted product. Therefore, the best ratio of the lysis solution volume to the sample mass should be explored and optimized before the experiment. The following recommended values for the amount of sample that can be lysed with only 1 ml of lysing solution are for reference only. Q 9: How is the sample treated for total RNA extraction? A9-1: Theoretically, the fresher the sample, the better the quality of total RNA extracted. If timely extraction is not possible, samples need to be frozen quickly with liquid nitrogen and then stored at -80 ° C at all times. Repeated freezing and thawing of samples have a great impact on the quality of extracted RNA. A9-2: Disruption: Complete disruption of tissue structures, cell walls, and plasma membranes is absolutely necessary to release all of the RNA in the sample. Different samples require different methods to achieve complete fragmentation. Incomplete fragmentation results in a significant reduction in RNA yield. A9-3: Homogenate: Homogenate is necessary to reduce the viscosity of the cell lysate after disruption. The homogenate is capable of cleaving high molecular weight genomic DNA and other high molecular weight cellular components to yield a homogeneous lysate. Incomplete homogenization will lead to the decrease of RNA binding efficiency and significantly reduce the yield. A9-4: Recommendations for different sample handling methods Q10: How to quantify RNA after extraction? A10-1: When testing RNA samples, it is necessary to ensure that RNase is removed from the cuvette, especially if it is still necessary to recover the RNA after the assay (the procedure can be followed by washing with 0.1 M NaOH, 1 mM EDTA, and water without RNa se in that order). A10-2: When measuring the absorbance value of A260 with a spectrophotometric timer using a UV-transparent plastic cuvette, the reading should be between 0.15 and 1.0. At the wavelength of A260, the absorbance value of 1 unit corresponds to an RNA concentration of 44 μg/ml (this correlation is only valid for detection under neutral pH conditions. Therefore, if RNA samples are to be diluted, a low salt buffer with a neutral pH of 10 mM Tris HCl, e.g., pH 7.0, should be used.) A10-3: example of RNA quantification RNA sample volume = 100 μl Dilution = 10 μl RNA sample + 490 μl 10 mM Tris HCl, pH 7.0 (dilution factor 1:50) Measure the absorbance of the diluted sample using a 1 ml RNase-free cuvette A260=0.2 RNA concentration = 44 μg/ml × A260 × dilution factor = 44μg/ml × 0.2× 50 =440μg/ml Article Source: Instrument and Equipment Test Special statement: The publication of this article is only for the purpose of disseminating information, and does not represent the views of this public account; if other media, websites or individuals reprint and use from this public account, please apply to the original author, and bear the copyright and other legal responsibilities. Instrument plus | dry goods finishing: chromatographic column use, wiped film distillation, maintenance and repair, all for you to organize together ~ do not collect it? Instrument Plus | News and Information: Southern Hemisphere Aerosol Content Breaks Record, Air Pollution Needs Urgent Attention! 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