Soil sampling device and soil sampling method based on three-dimensional induced liquefaction

Abstract

The invention provides a three-dimensional induced liquefaction-based soil sampling device and a soil sampling method.The soil sampling device comprises a drilling machine, a traction unit, a vertical vibration unit, a rotary vibration unit and a sampling drill rod, and the rotary vibration unit is used for driving the sampling drill rod to rotate and vibrate around the axis of the sampling drill rod; the vertical vibration unit is used for driving the rotary vibration unit to drive the sampling drill rod to vibrate in the vertical direction; the traction unit is used for driving the vertical vibration unit to drive the sampling drill rod to penetrate into the stratum and be pulled out of the stratum; the sampling drill rod comprises a drilling drill rod and a plurality of connecting drill rods, and the drilling drill rod and the connecting drill rods are each provided with an inner cavity; air outlet holes are distributed in the drilling rod; during use, the drilling rod and the connecting rods are sequentially connected from bottom to top. According to the soil sampling device based on three-dimensional induced liquefaction and the soil sampling method, when a soil sample below the underground water level is collected, disturbance is reduced, the 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. Specifically, it relates to a soil sampling device and a soil sampling method based on three-dimensional induced liquefaction. Background Art

[0002] Existing sonic vibration type soil sampling drills and their supporting control methods can form a liquefaction zone in the area near the contact surface between the sampling drill rod and the soil, reducing the penetration resistance during the sampling process and the compression disturbance to the soil around the drill bit, improving the quality and fidelity of soil samples to a certain extent, and being applied in sampling in low-viscosity sandy soil strata. However, since pollutants in contaminated sites often accumulate in high-viscosity fine-grained soil layers, such as silt and silty clay, due to the small particle size and large cohesion of cohesive soil, it is difficult to achieve a good liquefaction state under sonic vibration, and the collected samples still have large deformations and the soil structure is significantly changed. Therefore, it is urgent to improve the existing sonic vibration type soil sampling drills and methods, strive to change the physical state of the soil in the area near the contact surface between the sampling drill rod and the soil, enhance the liquefaction trend of the soil mass during the sampling process, and obtain high-quality and fidelity soil samples by reasonably controlling the thickness of the liquefaction zone, providing technical support for the design and later management of green and low-carbon remediation and risk control projects in contaminated sites. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: to provide a soil sampling device and a soil sampling method based on three-dimensional induced liquefaction, which can reduce disturbance, prevent the soil structure from changing, and improve the fidelity effect of soil samples when collecting soil samples below the groundwater level.

[0004] To solve the above technical problem, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a soil sampling device based on three-dimensional induced liquefaction, including a drill rig, a traction unit, a vertical vibration unit, a rotary vibration unit, and a sampling drill rod. The sampling drill rod is installed on the drill rig through the rotary vibration unit, the vertical vibration unit, and the traction unit in sequence; the rotary vibration unit is used to drive the sampling drill rod to rotate and vibrate around its own axis, and the vertical vibration unit is used to drive the rotary vibration unit to drive the sampling drill rod to vibrate in the vertical direction; the traction unit is used to drive the vertical vibration unit to move along the guiding beam of the drill rig, and drive the sampling drill rod to penetrate into the formation and pull out from the formation through the rotary vibration unit; the sampling drill rod includes a drilling drill rod and a plurality of connecting drill rods, and both the drilling drill rod and the connecting drill rods have inner cavities; air outlet holes are arranged on the drilling drill rod; during use, the drilling drill rod and the plurality of connecting drill rods are connected in sequence from bottom to top.

[0005] As a further improvement of the present invention, the drilling drill rod includes a hollow first rod body, on which a first gas transmission channel is arranged along its axial direction; a plurality of groups of gas outlet holes are arranged on the first rod body at intervals along the axial direction, each group of gas outlet holes includes a plurality of gas outlet holes distributed at intervals along the circumference of the first rod body, and the gas outlet holes are connected to the first gas transmission channel; a gas disperser is provided in each gas outlet hole; the connecting drill rod includes a hollow second rod body, on which a second gas transmission channel is provided running through both ends thereof.

[0006] As a further improvement of the present invention, the distance between two adjacent groups of air outlet holes is 0.3-0.5 m; in each group of air outlet holes, the ratio of the number of air outlet holes to the diameter of the first rod body is 30-50 / m.

[0007] As a further improvement of the present invention, the rotational vibration unit includes a top plate, a rotational driving member, a first gear, a second gear and a clamp, and the clamp is used to clamp the sampling drill rod; the top plate is installed on the vertical vibration unit, and the first gear, the second gear and the clamp are all rotatably installed on the top plate; the rotational driving member is connected to the first gear, and is used to drive the first gear to rotate; the first gear and the second gear are meshed; a first lever is provided on the first gear, a second lever is provided on the second gear, and a first protrusion and a second protrusion are provided on the clamp at intervals; when in use, the rotational driving member drives the first gear and drives the second gear to rotate, the first lever drives the first protrusion to make the clamp rotate forward, and the second lever drives the second protrusion to make the clamp rotate reversely; the first lever and the second lever work alternately, so that the clamp drives the sampling drill rod to perform forward and reverse rotational vibration.

[0008] In a second aspect, the present invention further provides a soil sampling method based on three-dimensional induced liquefaction, using the soil sampling device provided in the first aspect; the soil sampling method comprises the following steps: Step 10, drilling to the groundwater level; Step 20, when the sampling drill rod penetrates below the groundwater level to collect soil samples, the drilling rod 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; the vertical vibration unit drives the rotary vibration unit to drive the sampling drill rod to vibrate back and forth in the vertical direction, and the rotary vibration unit drives the sampling drill rod to rotate and vibrate forward and reversely around its own axis, thereby promoting the liquefaction of the soil near the drilling rod until the soil sample within the preset sampling depth range is taken out.

[0009] As a further improvement of the present invention, the vibration frequencies of the vertical vibration unit and the rotational vibration unit are both 80-120 Hz.

[0010] As a further improvement of the present invention, the amplitude of the vertical vibration unit is determined using formula (1): Formula (1) In the formula, represents the amplitude of the vertical vibration unit, with the unit of mm; represents the median particle size of soil particles, with the unit of mm; represents the first shape parameter adjustment coefficient, with a value range of -1.3 to -0.7, dimensionless; I p represents the plasticity index of soil, dimensionless; I p0 represents the reference plasticity index of soil, with a value range of 4 to 7, dimensionless; β represents the activity adjustment coefficient, with a value range of 0.15 to 0.45, with the unit of mm.

[0011] As a further improvement of the present invention, the amplitude of the rotary vibration unit is determined by Equation (2): Equation (2) In the formula, represents the amplitude of the rotary vibration unit; represents the diameter of the drilling drill pipe, with the unit of cm; represents the second shape parameter adjustment coefficient, with a value range of -13 to -7, dimensionless.

[0012] As a further improvement of the present invention, the flow rate of the gas introduced into the drilling drill pipe is determined by Equation (3): Equation (3) In the formula, represents the flow rate of the gas injected into the drilling drill pipe, with the unit of L / min; represents the average penetration speed of the drilling drill pipe, with the unit of m / min.

[0013] A soil sampling device and a soil sampling method based on three-dimensional induced liquefaction provided by the present invention. An air outlet is arranged on the lowermost drilling rod in the sampling drill rod, and the sampling drill rod can perform horizontal forward and reverse rotational vibrations driven by a rotational vibration unit and perform vertical reciprocating vibrations driven by a vertical vibration unit. During the process of collecting soil samples below the groundwater level, after micro-nano bubbles are introduced between the sampling drill rod and the soil contact surface, under the vibration load, the micro-nano bubbles significantly extend the drainage path through cyclic compression-expansion effects, enhancing the accumulation of excess pore water pressure, thereby promoting the liquefaction trend of the soil mass. Considering that clay minerals are in a layered or flaky structure and are mostly horizontally oriented during deposition, forming anisotropic characteristics with low vertical permeability and high horizontal permeability. At the beginning of liquefaction, the excess pore water pressure tends to diffuse along the path with higher horizontal permeability, triggering dominant horizontal seepage; at the same time, due to the face-to-face structure between particles, the extension distance of the force chains in the liquefied area in the vertical direction is significantly greater than that in the lateral direction. Therefore, the present invention uses the three-dimensional high-frequency vibration of the sampling drill rod moving up and down in the vertical direction and rotating forward and backward in the horizontal direction, combined with the effect of increasing pore pressure by dissolving micro-nano bubbles in the pore water, to promote the synchronous fracture of the contact bonds of soil particles near the contact surface between the drilling rod and the soil in the vertical and horizontal directions, inducing soil liquefaction within a smaller range, effectively reducing the thickness of the disturbed layer of the collected soil core sample. Thereby reducing disturbance, preventing the change of soil structure, and improving the fidelity effect of soil samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic structural diagram of a soil sampling device based on three-dimensional induced liquefaction according to an embodiment of the present invention; Figure 2 is Figure 1 the schematic structural diagram of the rotational vibration unit in Figure 3 is Figure 1 the cross-sectional view of the drilling rod in Figure 4 is Figure 1 the cross-sectional view of the connecting drill rod in Figure 5 is Figure 1 the cross-sectional view of the top cap in Figure 6 is Figure 1 the installation schematic diagram of the traction unit, vertical vibration unit and rotational vibration unit in

[0015] In the figure: drilling drill pipe 1, first rod body 11, first gas transmission channel 12, air outlet hole 13, gas disperser 14, connecting drill pipe 2, second rod body 21, second gas transmission channel 22, micro-nano bubble 3, top cap 4, cap body 41, third gas transmission channel 42, traction unit 5, vertical vibration unit 6, rotary vibration unit 7, first gear 71, first lever 711, second gear 72, second lever 721, fixture 73, first convex block 731, second convex block 732, gas flow controller 8, gas storage tank 9, groundwater level 10, ground 11, guiding crossbeam 12 of the drill rig. Detailed implementation manners

[0016] The technical solution of the present invention will be described in detail below.

[0017] An embodiment of the present invention provides a soil sampling device based on three-dimensional induced liquefaction, as Figure 1 shown, including a drill rig, a traction unit 5, a vertical vibration unit 6, a rotary vibration unit 7 and a sampling drill pipe. The sampling drill pipe is installed on the rotary vibration unit 7. As Figure 6 shown, the rotary vibration unit 7 is installed on the vertical vibration unit 6, the vertical vibration unit 6 is installed on the traction unit 5, and the traction unit 5 is slidably installed on the guiding beam 12 of the drill rig.

[0018] As Figure 6 shown, the rotary vibration unit 7 is used to drive the sampling drill pipe to rotate and vibrate forward and backward around its own axis. The vertical vibration unit 6 is used to drive the rotary vibration unit 7 to drive the sampling drill pipe to vibrate reciprocally in the vertical direction. The traction unit 5 is used to drive the vertical vibration unit 6 to move along the guiding beam of the drill rig, and drive the sampling drill pipe to penetrate into the formation and be pulled out from the formation through the rotary vibration unit 7. Both the traction unit 5 and the vertical vibration unit 6 adopt existing structures.

[0019] As a preferred example, as Figure 2As shown, the rotary vibration unit 7 includes a top plate, a rotary drive member, a first gear 71, a second gear 72, and a fixture 73 for clamping the sampling drill pipe. The top plate is mounted on the vertical vibration unit 6. The first gear 71, the second gear 72, and the fixture 73 are all rotatably mounted on the top plate through a rotating shaft. The rotary drive member is connected to the first gear 71 and is used to drive the first gear 71 to rotate. The first gear 71 and the second gear 72 are meshed with each other. A first lever 711 is provided on the first gear 71, and a second lever 721 is provided on the second gear 72. The first lever and the second lever are arranged in a staggered manner. The fixture 73 is provided with a first protrusion 731 and a second protrusion 732, and the first protrusion 731 and the second protrusion 732 are arranged at intervals. During use, the rotary drive member drives the first gear 71 to rotate. The first gear, as the driving gear, drives the second gear 72 to continuously rotate. When the first lever 711 rotates to the position of the first protrusion 731, the first lever 711 toggles the first protrusion 731 to cause the fixture 73 to rotate clockwise or counterclockwise. After the fixture rotates forward by a preset angle, the second lever 721 rotates to the position of the second protrusion 732, and the second lever 721 toggles the second protrusion 732 to cause the fixture 73 to rotate in the opposite direction. After the fixture rotates in the opposite direction by a preset angle, the first lever 711 toggles the first protrusion 731 again to cause the fixture 73 to rotate forward. In this way, the fixture drives the sampling drill pipe to perform forward and reverse rotary vibrations.

[0020] In this embodiment, two meshing gears are used to alternately toggle the fixture to rotate, so that the fixture switches between forward and reverse rotations, driving the sampling drill pipe to perform forward and reverse rotary vibrations. A relatively large torque can be obtained, the control is simple, the mechanical structure is fatigue-resistant, it is suitable for long-term high-frequency operation, and the processing and maintenance costs are low.

[0021] The sampling drill pipe includes a drilling drill pipe 1 and a connecting drill pipe 2, and both the drilling drill pipe and the connecting drill pipe have inner cavities. As Figure 3As shown, the drilling drill pipe 1 includes a hollow first rod body 11, and the bottom end of the first rod body 11 is conical. A first gas transmission channel 12 is arranged on the first rod body 11 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 hole groups are arranged on the first rod body 11 at intervals along the axial direction. Each group of air outlet hole groups includes a number of air outlet holes 13 arranged at intervals along the circumferential direction of the first rod body. The inlets of all the air outlet holes 13 in each group of air outlet hole groups are communicated through an annular channel, and the annular channel is communicated with the first gas transmission channel 12. The outlets of the air outlet holes are located on the outer wall surface of the first rod body. Thus, the air outlet holes of all the air outlet hole groups are communicated with the first gas transmission channel. A gas disperser 14 is arranged at the outlet of each air outlet hole 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 hole 13. A first threaded convex head for connecting with a connecting rod body is arranged at the top end of the first rod body 11. Preferably, the distance between adjacent two groups of air outlet hole groups is 0.3 - 0.5 m. In each group of air outlet hole groups, the ratio of the number of air outlet holes 13 to the diameter of the first rod body is 30 - 50 pieces / m. If the number and spacing of the air outlet holes 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 outlet holes are too small, the loss quantity of the gas disperser increases, and the sampling economy is reduced. The air outlet holes are set with the number and spacing within the above ranges to promote the uniform distribution of the bubbles in the pores between the sampling drill pipe and the soil contact surface, and realize the synchronous liquefaction of the soil in the local range of the contact surface.

[0022] As Figure 4 shown, the connecting drill pipe 2 includes a hollow second rod body 21, and a second gas transmission channel 22 penetrating through the upper and lower ends of the second rod body 21 is arranged on the second rod body 21. A first threaded groove for connecting with the drilling rod body is arranged at the bottom end of the second rod body 21, and a second threaded convex head is arranged at the top end. Both the first threaded convex head and the second threaded convex head are adapted to the first threaded groove.

[0023] The sampling drill pipe further includes a top cap 4. As Figure 5 shown, the top cap 4 includes a cap body 41. A second threaded groove for connecting with the connecting drill pipe is arranged at the bottom end of the cap body 41, and the second threaded groove is adapted to the second threaded convex head of the connecting drill pipe. A third gas transmission channel 42 is opened on the cap body 41.

[0024] During use, as Figure 1As 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 pipe 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 pipe, the drilling drill pipe, and the connecting drill pipe are all equal. The rotary vibration unit 7 clamps the top cover 4, and the traction unit 5 drives the sampling drill pipe formed by connecting multiple connecting drill pipes and the drilling drill pipe to penetrate downward into the formation through the vertical vibration unit 6 and the rotary vibration unit 7. At the same time, the vertical vibration unit 6 drives the sampling drill pipe to reciprocate vertically through the rotary vibration unit 7, and the rotary vibration unit 7 drives the sampling drill pipe to rotate and vibrate forward and backward around its own axis.

[0025] An embodiment of the present invention also provides a soil sampling method based on three-dimensional induced liquefaction, using the soil sampling device of the above embodiment. The soil sampling method includes the following steps: Step 10, drill to the groundwater level 10 position.

[0026] Step 20, during the process of the sampling drill pipe penetrating downward below the groundwater level to collect soil samples, the drilling drill pipe 1 located at the bottom of the sampling drill pipe ejects micro-nano bubbles outward, and the micro-nano bubbles enter the soil around the drilling drill pipe. The vertical vibration unit 6 drives the rotary vibration unit 7 to drive the sampling drill pipe to reciprocate vertically, and the rotary vibration unit 7 drives the sampling drill pipe to rotate and vibrate forward and backward around its own axis to promote the liquefaction of the soil near the drilling drill pipe 1 until the soil samples within the preset sampling depth range are taken out.

[0027] If the groundwater level is relatively deep and the distance between the groundwater level 10 and the ground 11 is greater than the length of the drilling drill pipe, when collecting the first section of soil samples 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.

[0028] Step 20 specifically includes: Step 201, install the 1st, 2nd,..., m +1 connecting drill pipes 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 +1 connecting drill pipe 2 is near the ground. Among them, m is an integer greater than or equal to 0. p =1. Install the p th sampling pipe into the inner cavity of the drilling drill pipe.

[0029] Step 202, at the m + pAt the top of the root connection drill pipe, a top cap 4 is installed, and the top cap 4 is connected to the rotary vibration unit 7. Gas is introduced 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 connection 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 repeatedly in the vertical direction, and the rotary vibration unit 7 drives the sampling drill pipe to rotate and vibrate forward and backward around its own axis, promoting the liquefaction of the soil near the drilling drill pipe, thereby reducing disturbance. The traction unit 5 drives the vertical vibration unit 6, the rotary vibration unit 7 and the sampling drill pipe to penetrate deep into the formation for sampling. When the m + p root connection drill pipe 2 is completely pressed into the formation, the gas supply is stopped, and the vertical vibration unit, the rotary vibration unit and the traction unit stop working. The rotary vibration unit 7 is separated from the top cap, and the top cap is separated from the m + p root connection drill pipe, and the p root sampling pipe is taken out to obtain the p section of soil sample below the groundwater level.

[0030] Step 203, install the m + p root connection drill pipe at the top of the m + p +1 root connection drill pipe 2. p value of is increased by 1. The p root sampling pipe is installed into the inner cavity of the drilling drill pipe. Repeat Step 202 until the soil samples within the predetermined depth range are taken out.

[0031] 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 sample below the groundwater level, it is not necessary to install a connection drill pipe at the top of the drilling drill pipe.

[0032] Step 20 specifically includes: Step 201, install the first root sampling pipe into the inner cavity of the drilling drill pipe, install a top cap 4 at the top of the drilling drill pipe, and connect the top cap to the rotary vibration unit.

[0033] Step 202: 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, then enters all the air outlet holes. The gas disperser 14 sprays out micro-nano bubbles, and the micro-nano bubbles enter the soil around the drilling drill pipe. Meanwhile, the vertical vibration unit 6 drives the sampling drill pipe to vibrate reciprocally in the vertical direction, and the rotary vibration unit 7 drives the sampling drill pipe to rotate and vibrate forward and backward around its own axis, promoting the liquefaction of the soil near the drilling drill pipe, thereby reducing disturbance. The traction unit 5 drives the vertical vibration unit 6, the rotary vibration unit 7 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 injecting gas, and the vertical vibration unit, the rotary vibration unit and the traction unit stop working. Separate the rotary vibration unit from the top cap, separate the top cap from the drilling drill pipe, take out the first sampling tube, and obtain the first soil sample below the groundwater level.

[0034] Step 203: Install the first connecting drill pipe at the top end of the drilling drill pipe. n = 1.

[0035] Step 204: Install the (n + 1)-th sampling tube into the inner cavity of the drilling drill pipe, install a top cap at the top end of the n-th connecting drill pipe, and connect the top cap to the rotary vibration unit.

[0036] 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 through the second gas transmission channel of the connecting drill pipe, then enters all the air outlet holes. The gas disperser 14 sprays out micro-nano bubbles, and the micro-nano bubbles enter the soil around the drilling drill pipe. Meanwhile, the vertical vibration unit 6 drives the sampling drill pipe to vibrate repeatedly in the vertical direction, and the rotary vibration unit 7 drives the sampling drill pipe to rotate and vibrate forward and backward around its own axis, promoting the liquefaction of the soil near the drilling drill pipe, thereby reducing disturbance. The traction unit 5 drives the vertical vibration unit 6, the rotary vibration unit 7 and the sampling drill pipe to penetrate deep into the formation for sampling. When the n-th connecting drill pipe 2 is completely pressed into the formation, stop injecting gas, and the vertical vibration unit, the rotary vibration unit and the traction unit stop working. Separate the rotary vibration unit from the top cap, separate the top cap from the n-th connecting drill pipe, take out the (n + 1)-th sampling tube, and obtain the (n + 1)-th soil sample below the groundwater level.

[0037] Step 206: Install the (n + 1)-th second drill pipe at the top end of the n-th 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.

[0038] Preferably, the vibration frequencies of both the vertical vibration unit 6 and the rotary vibration unit 7 are 80 - 120 Hz.

[0039] Preferably, the amplitude of the vertical vibration unit is determined by Equation (1): Formula (1) Wherein, represents the amplitude of the vertical vibration unit, with the unit of mm. represents the median particle size of soil particles, with the unit of mm; among all soil particles, 50% by mass of the particles have a particle size exceeding and 50% of the particles have a particle size lower than . represents the first shape parameter adjustment coefficient, with a value range of -1.3 to -0.7, 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 0.15 to 0.45, with the unit of mm.

[0040] In this embodiment, the amplitude of the vertical vibration unit is determined according to the particle size of soil particles and the plasticity index of the soil, and the soil near the contact surface between the drilling rod and the soil is liquefied, so that a liquefied zone with a suitable thickness range can be obtained, reducing the degree of disturbance damage.

[0041] Use Formula (2) to determine the amplitude of the rotary vibration unit 7: Formula (2) Wherein, represents the amplitude of the rotary vibration unit; represents the diameter of the drilling rod, with the unit of cm; represents the second shape parameter adjustment coefficient, with a value range of -13 to -7, dimensionless.

[0042] In this embodiment, the amplitude of the rotary vibration unit is determined according to the particle size of soil particles and the diameter of the drilling rod, promoting the synchronous fracture of the contact bonds of soil particles near the contact surface between the drilling rod and the soil in the vertical and horizontal directions, inducing soil liquefaction within a smaller range, and effectively reducing the thickness of the disturbed layer of the collected soil core sample.

[0043] Preferably, use Formula (3) to determine the gas injection flow rate into the drilling rod: Formula (3) Wherein, represents the gas injection flow rate into the drilling rod, with the unit of L / min; represents the average penetration speed of the drilling rod, with the unit of m / min.

[0044] In this embodiment, an appropriate amount of gas is introduced to coordinate with the drilling process, ensuring 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 in the soil near the contact surface is uniform, avoiding the formation of preferential channels for bubble migration and reducing the sampling fidelity effect.

[0045] Preferably, the diffusion range of the micro-nano bubbles is 0.3 to 0.6 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.

[0046] 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, and 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 soil sampling device based on three-dimensional induced liquefaction, characterized in that: The invention comprises a drilling rig, a traction unit (5), a vertical vibration unit (6), a rotational vibration unit (7) and a sampling drill rod, wherein the sampling drill rod is installed on the drilling rig via the rotational vibration unit (7), the vertical vibration unit (6) and the traction unit (5) in sequence; the rotational vibration unit (7) is used to drive the sampling drill rod to rotate and vibrate around its own axis, and the vertical vibration unit (6) is used to drive the rotational vibration unit (7) to drive the sampling drill rod to vibrate in a vertical direction; the traction unit (5) is used to drive the vertical vibration unit (6) to move along the guide beam of the drilling rig, and drive the sampling drill rod to penetrate into the formation and be pulled out of the formation via the rotational vibration unit (7); the sampling drill rod comprises a drilling drill rod (1) and a plurality of connecting drill rods (2), and the drilling drill rod (1) and the connecting drill rod (2) both have an inner cavity; an air outlet hole (13) is arranged on the drilling drill rod (1); when in use, the drilling drill rod (1) and the plurality of connecting drill rods (2) are sequentially connected from bottom to top.

2. The soil sampling device based on three-dimensional induced 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 comprises a plurality of gas outlet holes (13) distributed at intervals along the circumference of the first rod body, the gas outlet holes (13) being connected to the first gas transmission channel (12); a gas disperser (14) is arranged in each gas outlet hole (13); the connecting drill rod (2) comprises a hollow second rod body (21), the second rod body (21) being provided with a second gas transmission channel (22) running through both ends thereof.

3. The soil sampling device based on three-dimensional induced liquefaction according to claim 2, 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.

4. The soil sampling device based on three-dimensional induced liquefaction according to claim 1, characterized in that: The rotary vibration unit (7) comprises a top plate, a rotation driving member, a first gear (71), a second gear (72) and a clamp (73), wherein the clamp (73) is used to clamp a sampling drill rod; the top plate is mounted on the vertical vibration unit (6), and the first gear (71), the second gear (72) and the clamp (73) are all rotatably mounted on the top plate; the rotation driving member is connected to the first gear (71) and is used to drive the first gear (71) to rotate; the first gear (71) and the second gear (72) are meshed; a first shifting rod (73) is provided on the first gear (71); 11), a second lever (721) is provided on the second gear (72), and a first protrusion (731) and a second protrusion (732) are provided on the clamp (73) at intervals; when in use, the rotating driving member drives the first gear and drives the second gear to rotate, the first lever (711) drives the first protrusion (731) to make the clamp (73) rotate in the forward direction, and the second lever (721) drives the second protrusion (732) to make the clamp (73) rotate in the reverse direction; the first lever (711) and the second lever (721) work in turn, so that the clamp drives the sampling drill rod to perform forward and reverse rotation vibration.

5. A soil sampling method based on three-dimensional induced liquefaction, characterized in that: The soil sampling device according to any one of claims 1 to 4 is used; the soil sampling method comprises the following steps: 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; the vertical vibration unit (6) drives the rotary vibration unit (7) to drive the sampling drill rod to vibrate back and forth in the vertical direction, and the rotary vibration unit (7) drives the sampling drill rod to rotate and vibrate forward and reversely around its own axis, thereby promoting the liquefaction of the soil near the drilling rod (1), until the soil sample within the preset sampling depth range is taken out.

6. The soil sampling method based on three-dimensional induced liquefaction according to claim 5, characterized in that: The vibration frequencies of the vertical vibration unit (6) and the rotational vibration unit (7) are both 80 to 120 Hz.

7. The soil sampling method based on three-dimensional induced liquefaction according to claim 5, 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 size of soil particles, in mm; It represents the first shape parameter adjustment coefficient, with a value range of -1.3 to -0.7 and 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 0.15 to 0.45, in units of mm.

8. The soil sampling method based on three-dimensional induced liquefaction according to claim 5, characterized in that: The amplitude of the rotational vibration unit (7) is determined using equation (2): Formula (2) In the formula, represents the amplitude of the rotational vibration unit; Indicates the diameter of the drilling rod, in cm; Represents the second shape parameter adjustment coefficient, ranging from -13 to -7, dimensionless.

9. The soil sampling method based on three-dimensional induced liquefaction according to claim 5, characterized in that: Use formula (3) to determine the flow rate of gas introduced into the drilling pipe: Formula (3) In the formula, Indicates the flow rate of gas injected into the drilling drill pipe, in L / min; It indicates the average penetration speed of the drilling rod, in m / min.

10. The soil sampling method based on three-dimensional induced liquefaction according to claim 5, characterized in that: The diffusion range of micro-nano bubbles is 0.3 to 0.6 times the length of the drilling rod.

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