Low-disturbance soil sampling method based on active enhanced liquefaction

Abstract

The invention provides a low-disturbance soil sampling method based on active enhanced liquefaction. The low-disturbance soil sampling method comprises the following steps: step 10, drilling to an underground water level position; 20, in the process that the sampling drill rods penetrate into the position below the underground water level to collect the soil sample, the lowest drilling drill rod in the sampling drill rods sprays micro-nano bubbles outwards, and the micro-nano bubbles enter soil bodies around the drilling drill rods; meanwhile, the vertical vibration unit drives the sampling drill rod to vibrate in a reciprocating mode in the vertical direction, and liquefaction of the soil body near the drilling drill rod is promoted until the soil sample within the preset sampling depth range is taken out. According to the low-disturbance soil sampling method based on active enhanced liquefaction provided by the invention, when a soil sample below an underground water level is collected, disturbance is reduced, a soil structure is prevented from being changed, and the fidelity effect of the soil sample is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of soil drilling and sampling, and specifically relates to a low-disturbance soil sampling method based on active enhanced liquefaction. Background Art

[0002] True-fidelity sampling of contaminated sites is the basis for green and low-carbon remediation and risk control of contaminated sites. When using existing static pressure penetration soil sampling drills and methods to collect soil samples, there are often large deformations, and the soil structure is significantly changed. Although the low-frequency (<30Hz) vibration function of the static pressure penetration soil sampling drill is used to induce slight liquefaction of the soil layer in the saturated zone below the groundwater level, the sampling efficiency and the original structure of the soil can be improved to a certain extent. However, due to the small particle size and large cohesion between particles of cohesive soils such as silt and silty clay, it is difficult to achieve a good liquefaction state under the action of acoustic vibration, and the collected samples are still not ideal. Therefore, it is urgent to improve the existing static pressure penetration soil sampling drills and methods, reasonably control the liquefaction state and spatial range of the surrounding soil under the low-frequency vibration of the drill pipe, and effectively improve the sampling quality and efficiency of contaminated soil samples in cohesive soil layers. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: to provide a low-disturbance soil sampling method based on active enhanced liquefaction, which can reduce disturbance, prevent the change of soil structure, and improve the true-fidelity effect of soil samples when collecting soil samples below the groundwater level.

[0004] To solve the above technical problems, the present invention adopts the following technical solutions: The present invention provides a low-disturbance soil sampling method based on active enhanced liquefaction, including the following steps: Step 10, drilling to the groundwater level; Step 20, during the process of the sampling drill pipe penetrating downward below the groundwater level to collect soil samples, the micro-nano bubbles are ejected outward from the drilling drill pipe at the bottom of the sampling drill pipe, and the micro-nano bubbles enter the soil around the drilling drill pipe; at the same time, the vertical vibration unit drives the sampling drill pipe to vibrate reciprocally in the vertical direction to promote the liquefaction of the soil near the drilling drill pipe until the soil samples within the preset sampling depth range are taken out.

[0005] As a further improvement of the present invention, the vibration frequency of the vertical vibration unit is less than 30Hz.

[0006] As a further improvement of the present invention, the amplitude of the vertical vibration unit is determined by formula (1): Formula (1) In the formula, represents the amplitude of the vertical vibration unit, and the unit is mm; Represents the median particle size of the soil, with the unit of mm; Represents the shape adjustment coefficient, with the value range of -1.50 to -0.85, dimensionless; I p Represents the plasticity index of the soil, dimensionless; I p0 Represents the reference plasticity index of the soil, with the value range of 4 to 7, dimensionless; β Represents the activity adjustment coefficient, with the value range of 0.25 to 0.45, with the unit of mm.

[0007] As a further improvement of the present invention, the flow rate of the gas introduced into the drilling drill pipe is determined by formula (2): Formula (2) In the formula, Represents the flow rate of the gas injected into the drilling drill pipe, with the unit of L / min; Represents the diameter of the drilling drill pipe, with the unit of cm; Represents the average penetration speed of the drilling drill pipe, with the unit of m / min.

[0008] As a further improvement of the present invention, the drilling drill pipe includes a hollow first rod body, and a first gas transmission channel is arranged axially on the first rod body; a plurality of groups of air outlet hole groups are arranged at intervals along the axis on the first rod body, and each group of air outlet hole groups includes a plurality of air outlet holes arranged at intervals along the circumferential direction of the first rod body, and the air outlet holes are communicated with the gas transmission channel; a gas disperser is arranged in each air outlet hole.

[0009] As a further improvement of the present invention, the distance between adjacent two groups of air outlet hole groups is 0.3 to 0.5 m; in each group of air outlet hole groups, the number of air outlet holes is 30 to 50 per meter compared with the diameter of the first rod body.

[0010] As a further improvement of the present invention, the gas disperser includes a gas distribution plate and a semi-permeable membrane, and the semi-permeable membrane covers the air outlet side of the gas distribution plate.

[0011] As a further improvement of the present invention, the pressure of the gas injected into the drilling drill pipe is 1.05 times the sum of the hydrostatic pressure and the bubble point pressure of the semi-permeable membrane; the diffusion range of the micro-nano bubbles is 0.5 to 0.8 times the length of the drilling drill pipe.

[0012] As a further improvement of the present invention, the sampling drill pipe further includes a connecting drill pipe, and the connecting drill pipe includes a hollow second rod body, and a second gas transmission channel penetrating through both ends is arranged on the second rod body; during use, the drilling drill pipe is sequentially connected with a plurality of connecting drill pipes from bottom to top.

[0013] As a further improvement of the present invention, step 20 specifically includes: Step 201: Install the 1st, 2nd, …, the m +1st connecting drill pipes in sequence at the top end of the drilling drill pipe until the bottom end of the drilling drill pipe reaches the groundwater level position and the bottom end of the m +1st connecting drill pipe is near the ground surface; m is an integer greater than or equal to 0; p =1; Load the p th sampling pipe into the inner cavity of the drilling drill pipe; Step 202: Pass gas into the first gas transmission channel of the drilling drill pipe through the second gas transmission channel of the connecting drill pipe. The drilling drill pipe ejects micro-nano bubbles, and the micro-nano bubbles enter the soil around the drilling drill pipe. At the same time, the vertical vibration unit drives the sampling drill pipe to reciprocate vertically to promote the liquefaction of the soil near the drilling drill pipe, thereby reducing disturbance. The traction unit drives the vertical vibration unit and the sampling drill pipe to penetrate deep into the formation for sampling. When the m + p th connecting drill pipe is completely pressed into the formation, stop passing gas, and the vertical vibration unit and the traction unit stop working. Take out the p th sampling pipe to obtain the p th section of soil sample below the groundwater level; Step 203: Install the m + p +1st connecting drill pipe at the top end of the m + p +1st connecting drill pipe, increase the value of p by 1; Load the p th sampling pipe into the inner cavity of the drilling drill pipe; Repeat Step 202 until the soil samples within the predetermined depth range are taken out.

[0014] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: A low-disturbance soil sampling method based on active enhanced liquefaction provided by the present invention, during the process of collecting soil samples below the groundwater level, an appropriate volume of micro-nano bubbles is introduced between the lowermost drilling drill pipe in the sampling drill pipe and its contact surface with the soil. The micro-nano bubbles on the contact surface are small in size and large in specific surface area, and can stay for a long time. On the one hand, under the vibration load, the micro-nano bubbles significantly extend the drainage path through the cyclic compression-expansion effect, enhance the accumulation of excess pore water pressure, and thus promote soil liquefaction. On the other hand, under the vibration action, the micro-nano bubbles can occupy a certain volume of soil pores, interfere with the effective stress transfer between particles, hinder the extension of the force chain, and promote the rearrangement of soil particles within a smaller range. In addition, the micro-nano bubbles can form a gas-liquid mixed lubricating layer between the drilling drill pipe and the soil contact surface, reduce the direct frictional contact between the surface of the drilling drill pipe and soil particles, and due to the compressibility of the bubbles, an appropriate volume of micro-nano bubbles can dynamically adjust the interface state during vibration, reduce the friction coefficient, and thus reduce the disturbance of soil samples during the sampling process. Description of the Drawings

[0015] Figure 1 is a flowchart of the method of the embodiment of the present invention; Figure 2 is a construction schematic diagram of the method of the embodiment of the present invention; Figure 3 is Figure 2 a cross-sectional view of the drilling drill pipe in Figure 4 is Figure 3 an A-A' sectional view of the drilling drill pipe in Figure 5 is Figure 2 a cross-sectional view of the connecting drill pipe in Figure 6 is Figure 2 a cross-sectional view of the top cap in Figure 7 is Figure 3 a structural schematic diagram of the gas disperser in

[0016] In the figure: drilling drill pipe 1, first rod body 11, first gas transmission channel 12, air outlet hole 13, gas disperser 14, air distribution plate 141, semi-permeable membrane 142, connecting drill pipe 2, second rod body 21, second gas transmission channel 22, micro-nano bubbles 3, top cap 4, cap body 41, third gas transmission channel 42, traction unit 5, vertical vibration unit 6, clamp 7, gas flow controller 8, gas storage tank 9, groundwater level 101, ground 102, drill rig 120. Detailed Embodiment

[0017] The technical solution of the present invention will be described in detail below.

[0018] An embodiment of the present invention provides a low-disturbance soil sampling method based on active enhanced liquefaction, as Figure 1 shown, which includes the following steps: Step 10, drill to the groundwater level at position 10.

[0019] In step 20, during the process of the sampling drill rod penetrating downward below the groundwater level to collect soil samples, micro-nano bubbles are ejected outward from the lowermost drilling drill rod in the sampling drill rod, and the micro-nano bubbles enter the soil mass around the drilling drill rod. At the same time, the vertical vibration unit drives the sampling drill rod to reciprocate in the vertical direction to promote the liquefaction of the soil mass near the drilling drill rod. Until the soil samples within the preset sampling depth range are taken out.

[0020] The method of the embodiment of the present invention uses a low-disturbance drill to collect soil samples below the groundwater level. As Figure 2 shown, the low-disturbance drill includes a drill rig 12, a traction unit 5, a vertical vibration unit 6, a clamp 7, and a sampling drill rod. The traction unit 5 is slidably installed on the guide beam of the drill rig 12. The vertical vibration unit 6 is installed on the traction unit 5. The clamp 7 is installed on the vertical vibration unit 6. The clamp 7 is used to clamp the sampling drill rod. The traction unit 5 is used to drive the sampling drill rod to move along the guide beam of the drill rig, drive the sampling drill rod to penetrate downward into the formation and drive the sampling drill rod to be pulled out from the formation. The vertical vibration unit 6 is used to drive the sampling drill rod to reciprocate in the vertical direction. Both the traction unit 5 and the vertical vibration unit 6 adopt existing structures.

[0021] The sampling drill rod includes a drilling drill rod 1 and a connecting drill rod 2, and both the drilling drill rod and the connecting drill rod have inner cavities. As Figure 3 shown, the drilling drill rod 1 includes a hollow first rod body 11, and the bottom end of the first rod body 11 is conical. The first rod body 11 is provided with a first gas transmission channel 12 distributed along its axial direction, and the inlet of the first gas transmission channel 12 is located on the top end surface of the first rod body 11. A plurality of groups of air outlet groups are arranged at intervals along the axial direction on the first rod body 11. Each group of air outlet groups includes a number of air outlets 13 arranged at intervals along the circumferential direction of the first rod body. As Figure 4As shown, the inlets of all the air outlets 13 in each air outlet group are connected through an annular channel, and the annular channel is connected to the first gas transmission channel 12. The outlets of the air outlets 13 are located on the outer wall surface of the first rod body. Thus, the air outlets of all the air outlet groups are connected to the first gas transmission channel. A gas disperser 14 is provided at the outlet of each air outlet 13. The gas disperser 14 is used to generate micro-nano bubbles and block the groundwater in the soil layer from entering the air outlet 13. A first threaded boss for connecting with a connecting rod body is provided at the top end of the first rod body 11. Preferably, the distance between adjacent two air outlet groups is 0.3 - 0.5 m. In each air outlet group, the ratio of the number of air outlets 13 to the diameter of the first rod body is 30 - 50 per meter. If the number and spacing of the air outlets are too large, strange migration dominant channels will be generated, and the overall liquefaction of the soil near the contact surface cannot be achieved; if the number and spacing of the air outlets are too small, the loss quantity of the gas disperser increases, and the sampling economy decreases. The number and spacing of the air outlets are set within the above ranges to promote the uniform distribution of bubbles in the pores between the sampling drill rod and the soil contact surface, and realize the synchronous liquefaction of the soil in the local range of the contact surface.

[0022] As Figure 7 shown, the gas disperser 14 includes a gas distribution plate 141 and a semi-permeable membrane 142. The semi-permeable membrane 142 covers the air outlet side of the gas distribution plate 141. It realizes the diffusion of gas to the contact surface between the drilling drill rod 1 and the surrounding soil, while the groundwater cannot enter the gas transmission channel 12.

[0023] As Figure 5 shown, the connecting drill rod 2 includes a hollow second rod body 21, and a second gas transmission channel 22 penetrating through its upper and lower ends is provided on the second rod body 21. A first threaded groove for connecting with the drilling rod body is provided at the bottom end of the second rod body 21, and a second threaded boss is provided at the top end. Both the first threaded boss and the second threaded boss are adapted to the first threaded groove.

[0024] The sampling drill rod further includes a top cap 4. As Figure 6 shown, the top cap 4 includes a cap body 41. A second threaded groove for connecting with the connecting drill rod is provided at the bottom end of the cap body 41, and the second threaded groove is adapted to the second threaded boss of the connecting drill rod. A third gas transmission channel 42 is provided on the cap body 41.

[0025] During use, as Figure 2As shown, the top cover 4, multiple connecting drill pipes 2, and the drilling drill pipe 1 are connected in sequence from top to bottom to form a sampling drill pipe. The inner cavities of the connecting drill pipe and the drilling drill pipe are connected in sequence to form a sampling cavity. The third gas transmission channel 42, multiple second gas transmission channels 22, and the first gas transmission channel 12 are connected in sequence. The sampling tube is installed in the sampling cavity. Among them, the number of connecting drill pipes is determined according to the on-site collection depth. Preferably, the lengths of the sampling tube, the drilling drill pipe, and the connecting drill pipe are all equal. The fixture clamps the top cover, and the traction unit 5 drives the sampling drill pipe formed by connecting multiple connecting drill pipes and the drilling drill pipe to penetrate vertically into the formation through the vertical vibration unit and the fixture. At the same time, the vertical vibration unit 6 drives the sampling drill pipe to reciprocate vertically through the fixture.

[0026] If the groundwater level is relatively deep and the distance between the groundwater level 10 and the ground surface 11 is greater than the length of the drilling drill pipe, when collecting the first section of soil sample below the groundwater level, at least one connecting drill pipe needs to be connected to the top end of the drilling drill pipe until the bottom end of the drilling drill pipe reaches the groundwater level position.

[0027] Step 20 specifically includes: Step 201, install the 1st, 2nd,..., the m +1st connecting drill pipe 2 in sequence at the top end of the drilling drill pipe 1 until the bottom end of the drilling drill pipe 1 reaches the groundwater level position, and the bottom end of the m +1st connecting drill pipe 2 is near the ground surface. Among them, m is an integer greater than or equal to 0. p =1. Install the p th sampling tube into the inner cavity of the drilling drill pipe. Install the top cap 4 at the top end of the m + p th connecting drill pipe, and connect the top cap 4 to the vertical vibration unit 6.

[0028] Step 202, introduce gas into the third gas transmission channel 41 of the top cap. The gas enters the first gas transmission channel 12 of the drilling drill pipe 1 through the second gas transmission channel of the connecting drill pipe, and then enters all the air holes. The gas disperser 14 ejects micro-nano bubbles outward, and the micro-nano bubbles enter the soil around the drilling drill pipe. At the same time, the vertical vibration unit 6 drives the sampling drill pipe to reciprocate vertically, promoting the liquefaction of the soil near the drilling drill pipe, thereby reducing the disturbance. The traction unit 5 drives the vertical vibration unit 6 and the sampling drill pipe to penetrate deep into the formation for sampling. When the m + p th connecting drill pipe 2 is completely pressed into the formation, stop ventilating, and the vertical vibration unit and the traction unit stop working. Separate the vertical vibration unit 6 from the top cap, separate the top cap from the m + p th connecting drill pipe, take out the p th sampling tube, and obtain the p th section of soil sample below the groundwater level.

[0029] Step 203, install the m + p th connecting drill pipe at the top of the m + p +1st connecting drill pipe 2. p Increase the value of. Install the p th sampling pipe into the inner cavity of the drilling drill pipe. At the m + p th connecting drill pipe, install the top cap 4 at the top, and connect the top cap 4 to the vertical vibration unit 6. Repeat Step 202 until the soil samples within the predetermined depth range are taken out.

[0030] If the groundwater level is relatively shallow and the distance between the groundwater level 10 and the ground surface 11 is less than the length of the drilling drill pipe, when collecting the first section of soil samples below the groundwater level, it is not necessary to install the connecting drill pipe at the top of the drilling drill pipe.

[0031] Step 20 specifically includes: Step 201, install the first sampling pipe into the inner cavity of the drilling drill pipe, install the top cap 4 at the top of the drilling drill pipe, and connect the top cap 4 to the vertical vibration unit.

[0032] Step 202, introduce gas into the third gas transmission channel 41 of the top cap. The gas enters the first gas transmission channel 12 of the drilling drill pipe 1, and then enters all the air holes. The gas disperser 14 ejects micro-nano bubbles outward, and the micro-nano bubbles enter the soil around the drilling drill pipe. At the same time, the vertical vibration unit 6 drives the sampling drill pipe to reciprocate vertically, promoting the liquefaction of the soil near the drilling drill pipe, thereby reducing disturbance. The traction unit 5 drives the vertical vibration unit 6 and the sampling drill pipe to penetrate deep into the formation for sampling. When the drilling drill pipe is completely pressed into the formation, stop ventilating, and the vertical vibration unit and the traction unit stop working. Separate the vertical vibration unit 6 from the top cap, separate the top cap from the drilling drill pipe, and take out the first sampling pipe to obtain the first section of soil samples below the groundwater level.

[0033] Step 203, install the first connecting drill pipe at the top of the drilling drill pipe. n = 1.

[0034] Step 204, install the (n + 1)th sampling pipe into the inner cavity of the drilling drill pipe, install the top cap at the top of the nth connecting drill pipe, and connect the top cap 4 to the vertical vibration unit.

[0035] Step 205: Inject gas into the third gas transmission channel 41 of the top cap. The gas enters the first gas transmission channel 12 of the drilling drill pipe 1 through the second gas transmission channel connected to the drill pipe, and then enters all the air holes. The gas disperser 14 sprays out micro-nano bubbles, and the micro-nano bubbles enter the soil around the drilling drill pipe. At the same time, the vertical vibration unit 6 drives the sampling drill pipe to vibrate reciprocally in the vertical direction, promoting the liquefaction of the soil near the drilling drill pipe, thereby reducing disturbance. The traction unit 5 drives the vertical vibration unit 6 and the sampling drill pipe to penetrate deep into the formation for sampling. When the nth connecting drill pipe 2 is completely pressed into the formation, stop injecting gas, and the vertical vibration unit and the traction unit stop working. Separate the vertical vibration unit 6 from the top cap, separate the top cap from the nth connecting drill pipe, take out the (n + 1)th sampling pipe, and obtain the (n + 1)th soil sample below the groundwater level.

[0036] Step 206: Install the (n + 1)th second drill pipe at the top of the nth connecting drill pipe. Increase the value of n by 1. Repeat Steps 204 to 205 until the soil samples within the predetermined depth range are taken out.

[0037] Preferably, the vibration frequency generated by the vertical vibration unit is less than 30 Hz.

[0038] Preferably, the amplitude of the vertical vibration unit is determined by Equation (1): Equation (1) In the formula, represents the amplitude of the vertical vibration unit, with the unit of mm. represents the median particle size of the soil particles, with the unit of mm; 50% of the particles in all soil particles have a particle size exceeding and 50% of the particles have a particle size lower than . represents the shape adjustment coefficient, with a value range of -1.50 to -0.85, dimensionless; I p represents the plasticity index of the soil, dimensionless; I p0 represents the reference plasticity index of the soil, with a value range of 4 to 7, dimensionless; β represents the activity adjustment coefficient, with a value range of 0.25 to 0.45, with the unit of mm.

[0039] In this embodiment, the amplitude of the vertical vibration unit is determined according to the particle size of the soil particles and the plasticity index of the soil, and the soil near the contact surface between the drilling drill pipe and the soil is liquefied, so that a liquefied zone with a suitable thickness range can be obtained, reducing the degree of disturbance damage.

[0040] Preferably, the gas flow rate injected into the drilling drill pipe is calculated by Equation (2): Formula (2) In the formula represents the gas injection flow rate into the drilling drill pipe, with the unit of L / min. represents the diameter of the drilling drill pipe, with the unit of cm. represents the average penetration speed of the drilling drill pipe, with the unit of m / min.

[0041] In this embodiment, an appropriate amount of gas is introduced, which is coordinated with the drilling process to ensure that a uniform gas-liquid mixed lubricating layer is formed at the contact surface between the sampling drill pipe and the soil. At the same time, the saturation degree in the soil near the contact surface is uniform, avoiding the formation of preferential channels for bubble migration and reducing the sampling fidelity effect.

[0042] Preferably, the gas pressure injected into the drilling drill pipe is 1.05 times the sum of the hydrostatic pressure and the bubble point pressure of the semi-permeable membrane 142. This promotes the uniform exclusion of micro-nano bubbles from the gas disperser. Excessive or too small pressure will change the migration mode of gas in the semi-permeable membrane of the gas disperser, resulting in an unstable bubble generation process and increasing the control difficulty.

[0043] Preferably, the diffusion range of the micro-nano bubbles is 0.5 - 0.8 times the length of the drilling drill pipe. This diffusion range can fully cover the contact disturbance area between the sampling drill pipe and the soil during the sampling process, achieving the optimization of sampling fidelity effect and economy.

[0044] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above specific embodiments. The above specific embodiments and the descriptions in the specification are only for further explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A low-disturbance soil sampling method based on active enhanced liquefaction, characterized in that: The following steps are involved: Step 10, drilling to the groundwater level (10); Step 20, when the sampling drill rod is inserted below the groundwater level to collect soil samples, the drilling rod (1) located at the bottom of the sampling drill rod sprays out micro-nano bubbles, and the micro-nano bubbles enter the soil around the drilling rod; at the same time, the vertical vibration unit (6) drives the sampling drill rod to vibrate back and forth in the vertical direction, promoting the liquefaction of the soil near the drilling rod (1), until the soil sample within the preset sampling depth range is taken out.

2. The low-disturbance soil sampling method based on active enhanced liquefaction according to claim 1, characterized in that: The vibration frequency of the vertical vibration unit (6) is less than 30 Hz.

3. The low-disturbance soil sampling method based on active enhanced liquefaction according to claim 1, characterized in that: The amplitude of the vertical vibration unit (6) is determined using formula (1): Formula (1) In the formula, Indicates the amplitude of the vertical vibration unit, in mm; It represents the median particle size of soil in mm; It represents the shape adjustment coefficient, with a value range of -1.50 to -0.85 and is dimensionless; I p It represents the plasticity index of soil, dimensionless; I p0 It represents the base plasticity index of soil, ranging from 4 to 7, dimensionless; β It represents the activity adjustment coefficient, ranging from 0.25 to 0.45, in units of mm.

4. The low-disturbance soil sampling method based on active enhanced liquefaction according to claim 1, characterized in that: Use formula (2) to determine the flow rate of gas introduced into the drilling pipe: Formula (2) In the formula, Indicates the flow rate of gas injected into the drilling drill pipe, in L / min; Indicates the diameter of the drilling rod, in cm; It indicates the average penetration speed of the drilling rod, in m / min.

5. The low-disturbance soil sampling method based on active enhanced liquefaction according to claim 1, characterized in that: The drilling rod (1) comprises a hollow first rod body (11), the first rod body (11) being provided with a first gas transmission channel (12) arranged along its axial direction; a plurality of groups of gas outlet holes are arranged at intervals along the axial direction on the first rod body, each group of gas outlet holes comprising a plurality of gas outlet holes (13) arranged at intervals along the circumference of the first rod body, the gas outlet holes being connected to the gas transmission channel (12); and a gas disperser (14) is arranged in each gas outlet hole (13).

6. The low-disturbance soil sampling method based on active enhanced liquefaction according to claim 5, characterized in that: The spacing between two adjacent groups of air outlet holes is 0.3 to 0.5 m; in each group of air outlet holes, the ratio of the number of air outlet holes (13) to the diameter of the first rod body is 30 to 50 per meter.

7. The low-disturbance soil sampling method based on active enhanced liquefaction according to claim 5, characterized in that: The gas disperser (14) comprises an air distribution plate (141) and a semi-permeable membrane (142), wherein the semi-permeable membrane (142) covers the air outlet side of the air distribution plate (141).

8. The low-disturbance soil sampling method based on active enhanced liquefaction according to claim 7, characterized in that: The gas pressure injected into the drilling rod is 1.05 times the sum of the hydrostatic pressure and the bubble point pressure of the semipermeable membrane (142); the diffusion range of the micro-nano bubbles is 0.5 to 0.8 times the length of the drilling rod.

9. The low-disturbance soil sampling method based on active enhanced liquefaction according to claim 1, characterized in that: The sampling drill rod also includes a connecting drill rod, which includes a hollow second rod body (21) on which a second gas transmission channel (22) running through both ends is provided; when in use, the drilling drill rod and the plurality of connecting drill rods are connected in sequence from bottom to top.

10. The low-disturbance soil sampling method based on active enhanced liquefaction according to claim 1, characterized in that: The step 20 specifically includes: Step 201, install the first, second, ..., and third drill pipes in sequence at the top of the drilling rod. m +1 connecting drill rod, until the bottom of the drill rod reaches the groundwater level, and the m +1 The bottom end of the connecting drill pipe is located near the ground; m is an integer greater than or equal to 0; p =1; p A sampling tube is installed into the inner cavity of the drill pipe; Step 202: gas is introduced into the first gas delivery channel of the drilling rod through the second gas delivery channel connected to the drill rod, and the drilling rod sprays micro-nano bubbles outward, and the micro-nano bubbles enter the soil around the drilling rod; at the same time, the vertical vibration unit (6) drives the sampling drill rod to vibrate back and forth in the vertical direction, promoting the liquefaction of the soil near the drilling rod (1), thereby reducing disturbance; the traction unit (5) drives the vertical vibration unit (6) and the sampling drill rod to penetrate deep into the formation for sampling; when the m + p When all the connected drill pipes are pressed into the formation, stop ventilation, and stop the vertical vibration unit and traction unit from working; take out the first p A sampling tube was taken to obtain the first p Section soil samples; Step 203, in the m + p Install the first m + p +1 connecting drill pipe, p Increase the value of by 1; p A sampling tube is installed into the inner cavity of the drill pipe; step 202 is repeated until the soil sample within the predetermined depth range is taken out.

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