A survey sampling device suitable for soft soil and a use method thereof

Abstract

A kind of survey sampling device suitable for soft soil and use method, it is related to sampling technical field, the technical scheme adopted includes pedestal, sampling tube, outer tube and sample breaking device, the sampling tube one end is provided with outer convex ring;The first piston is arranged in the sampling tube inner chamber;The outer tube is shorter than sampling tube in length, the outer tube and the sampling tube form first external cavity;Sample breaking device includes second piston and movable sleeve, the movable sleeve and the sampling tube form second external cavity;The inner wall of the second tube shoe is further provided with ring groove, the ring groove is provided with limiting ring and constraint ring, the constraint ring can slide in the second external cavity in axial direction, the limiting ring and constraint ring form containing cavity for containing elastic ring.The disturbance to soil sample is reduced in the process of sampling, separating soil sample from soft soil and pulling out sampling tube, the accuracy of subsequent indoor soil test can be improved.

Description

Technical Field

[0001] This invention relates to the field of sampling technology, and in particular to a sampling device and method for surveying soft soil. Background Technology

[0002] Engineering surveying is a fundamental task in the early stages of engineering construction. Its main tasks include obtaining undisturbed soil samples. Whether the soil samples can maintain their physical state and structural characteristics in the original strata significantly affects the accuracy of subsequent indoor geotechnical tests. Excessive deviation can lead to engineering risks such as uneven foundation settlement. Soft soil generally refers to cohesive soil with high natural water content, high compressibility, low bearing capacity, and low shear strength, existing in a soft plastic or fluid plastic state. It is widely distributed in coastal sedimentary areas, river deltas, alluvial plains, and other areas with dense urban infrastructure. As engineering construction continues to expand into areas with complex geological conditions, the number of engineering projects within the soft soil range is increasing. Due to the characteristics of soft soil, such as high water content, low strength, low shear strength, and being mostly in a soft plastic or fluid plastic state, it is more easily disturbed during engineering surveys, making it difficult to obtain undisturbed soil samples.

[0003] For soft soils in a soft plastic or fluid plastic state, the currently recommended sampling device is the fixed piston thin-walled soil sampler. Its structure and related standards can be found in JG / T 551-2018 Fixed Piston Thin-Walled Soil Sampler. When using a fixed piston thin-walled soil sampler, the piston rod and piston must first be fixed. Then, the sampling tube is pressed into the soft soil using a static pressure method. The soil sample is then separated from the soft soil by pulling or twisting. During extraction, the pressure difference between the depth of the sampling tube and the external environment must be overcome. Although the fixed piston thin-walled soil sampler causes less disturbance to the soil sample due to its thin-walled structure and piston, the relatively rough separation and extraction methods can still damage the soil structure within the sampling tube and cause disturbance.

[0004] To address this issue, other types of sampling equipment typically incorporate a cutting device at the sampling tube shoe. This device activates when the sampling tube reaches a predetermined depth, physically separating the soil sample from the soft soil, reducing disturbance and preventing slippage or breakage during extraction. However, thin-walled samplers generally have relatively small wall thicknesses to meet standard requirements for area ratio; for example, the wall thickness of a 100 mm outer diameter sampling tube in the TG100 type fixed piston thin-walled sampler cannot exceed 3 mm. Such a thin-walled structure cannot support the addition of a cutting device at the sampling tube shoe. Summary of the Invention

[0005] To address the problem that existing thin-walled soil samplers still cause significant disturbance when separating soil samples from soft soil, this invention provides a survey and sampling device and method suitable for soft soil.

[0006] This invention provides the following technical solution: a sampling device suitable for soft soil exploration, comprising: A base, wherein the base is provided with a connecting cavity and a connector communicating with the connecting cavity; A sampling tube, one end of which is detachably connected to the base, and the other end of which is provided with a first tube shoe, the outer wall of which is provided with an external protruding ring; the inner cavity of the sampling tube is connected to the connecting cavity, and a first piston is provided in the inner cavity of the sampling tube, the piston rod of the first piston being slidably connected to the base; An outer tube is detachably connected to the base. The length of the outer tube is shorter than that of the sampling tube. The outer tube is disposed outside the sampling tube. The outer tube and the sampling tube form a first external cavity, which is connected to the connecting cavity. The sampling device includes a second piston and a movable sleeve disposed within the first external cavity. One end of the movable sleeve is connected to the second piston, and the other end is detachably connected to a second tube shoe. The inner diameter of the second tube shoe is greater than or equal to the outer diameter of the outer convex ring. The outer wall of the movable sleeve mates with the inner wall of the outer tube, and the movable sleeve and the sampling tube form a second external cavity. The inner wall of the second tube shoe is also provided with an annular groove. A limiting ring and a constraint ring inserted into the limiting ring are disposed in the annular groove. The limiting ring is engaged between the annular groove and the movable sleeve. The constraint ring can slide axially within the second external cavity. Both the inner wall of the limiting ring and the outer wall of the constraint ring are provided with L-shaped grooves, so that the limiting ring and the constraint ring form a receiving cavity for accommodating an elastic ring. The elastic ring is engaged within the L-shaped groove of the constraint ring.

[0007] Preferably, the length of the outer tube does not exceed 1 / 2 of the length of the sampling tube.

[0008] Preferably, the outer wall diameter of the first tube shoe gradually increases from bottom to top to form a tapered cutting edge, and the maximum diameter of the first tube shoe is greater than that of the sampling tube to form the outer convex ring.

[0009] Preferably, the outer wall of the sampling tube is further provided with a venting groove, the venting groove is covered by the outer tube, and the length of the venting groove is greater than the thickness of the second piston; the inner wall of the constraint ring is provided with a gap from the sampling tube.

[0010] Preferably, the outer wall of the constraint ring is provided with a plurality of protruding teeth along the circumferential direction, and the limiting ring is provided with a groove that mates with the protruding teeth.

[0011] Preferably, the constraint ring is further provided with an extension that is interference-fitted with the inner wall of the second tube shoe, and the outer wall of the extension is provided with a positioning protrusion.

[0012] Preferably, the inner wall of the limiting ring is further provided with a latch to fix one side of the elastic ring.

[0013] Preferably, the diameter of the elastic ring after reset is 2-5 cm.

[0014] A method for using an exploration and sampling device includes the following steps: S1, after expanding the elastic ring, it is fitted into the L-shaped groove of the constraint ring, then the constraint ring is inserted into the limiting ring, then the limiting ring is inserted into the ring groove of the second tube shoe, the second tube shoe is installed on the movable sleeve, the movable sleeve and the second piston are fitted onto the sampling tube, and finally the sampling tube and the outer tube are connected to the base in sequence. S2, connect the connector to the ventilation pipe, the ventilation pipe is connected to the air inlet pipe and the air outlet pipe respectively through the three-way valve, the air inlet pipe is connected to the air pump, and both the air inlet pipe and the air outlet pipe are equipped with shut-off valves; S3, open the exhaust pipe shut-off valve, lower the first piston to be flush with the bottom port of the sampling tube, and move the movable sleeve to the top; S4, place the bottom of the sampling tube at the sampling point, lock the piston rod, open the exhaust pipe shut-off valve, apply static pressure to the base to press the sampling device into the soft soil until the first preset depth; S5, close the exhaust pipe shut-off valve, open the air inlet pipe shut-off valve and air pump, press the sample cutting device down to the second predetermined depth, the air pump stops, close the air inlet pipe shut-off valve, the outer convex ring of the first tube shoe separates the constraint ring from the limit ring, and the elastic ring automatically contracts to cut off most of the soil column in the sampling tube. S6, pull out the sampling device and take out the soil sample.

[0015] Preferably, step S6 further includes continuing to introduce air when pulling out the tube, with the gas entering the bottom of the sampling tube through the first external cavity, the ventilation groove, and the second external cavity, thereby reducing the pressure difference between the bottom of the sampling tube and the outside.

[0016] The beneficial effects of this invention are as follows: During sampling, the thin-walled sampling tube cuts into the soft soil to collect soil samples. The relatively large-diameter cutting device and outer tube are located at the top of the sampling tube, which basically does not disturb the soil sample inside the sampling tube or the soft soil below the sampling tube, thus retaining the advantages of the fixed piston thin-walled sampling tube; the outer convex ring increases the gap between the sampling tube and the soft soil, reduces the frictional resistance between the sampling tube and the soft soil, and facilitates the descent of the cutting device; after sampling, the cutting device cuts off most of the cross-section of the soil sample, allowing the soil sample to be pulled out directly, greatly reducing the disturbance caused by pulling out the soil sample; the cutting device has a simple and easy-to-implement structure and is suitable for sampling soft soil in a soft plastic or fluid plastic state; it can inflate the bottom area of ​​the sampling tube to reduce the internal and external pressure difference, and the soil sample will not be disturbed or even fall off due to the negative pressure in the bottom area of ​​the sampling tube during the extraction process. Attached Figure Description

[0017] Figure 1 A three-dimensional schematic diagram of one embodiment of an exploration sampling device.

[0018] Figure 2 This is a cross-sectional view of one embodiment of the survey sampling device.

[0019] Figure 3 This is a three-dimensional schematic diagram of one embodiment of the second tube shoe.

[0020] Figure 4 A schematic diagram of the operation of one embodiment of the sample breaking device Figure I .

[0021] Figure 5 A schematic diagram of the operation of one embodiment of the sample breaking device Figure II .

[0022] Figure 6 for Figure 5 Enlarged view of part A.

[0023] Figure 7 for Figure 4 Enlarged view of part B.

[0024] Reference numerals: 10, base; 11, connecting cavity; 12, vent hole; 13, connector; 14, connector head; 20, sampling tube; 21, first tube shoe; 22, external convex ring; 23, first piston; 24, vent groove; 30, outer tube; 31, first external cavity; 40, sample breaking device; 41, second piston; 42, movable sleeve; 43, second tube shoe; 44, second external cavity; 45, limiting ring; 46, constraint ring; 461, protruding tooth; 462, extension; 47, elastic ring. Detailed Implementation

[0025] The embodiments of the present invention will be described in more detail below with reference to the accompanying drawings and reference numerals, so that those skilled in the art can implement them after reading this specification. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0026] This invention provides a sampling device suitable for soft soil exploration. Based on the existing fixed piston thin-walled soil sampler, it further reduces the disturbance caused during soft soil sampling in soft plastic or fluid plastic states, so that the obtained soft soil sample can maintain its physical state and structural characteristics in the original strata to the greatest extent, improve the accuracy of indoor geotechnical tests, and provide a basis for engineering construction.

[0027] Example 1

[0028] Please refer to Figure 1 , 2 The exploration and sampling device includes a base, a sampling tube, an outer tube, and a sample cutting device.

[0029] The first end of the base 10 is a tubular structure forming a connecting cavity 11. The bottom of the connecting cavity 11 is open, and vent holes 12 are provided on the side walls and top of the connecting cavity 11. The vent hole 12 on the top is also threadedly connected to a connector 13, through which a ventilation pipe can be connected. The second end of the base 10 is threadedly connected to a connector 14, which is slidably connected to the piston rod of the first piston 23.

[0030] The sampling tube 20 is a thin-walled circular tube. The relationship between its outer diameter and wall thickness should meet the area ratio specified in JG / T 551-2018 Fixed Piston Thin-Walled Soil Sampler to reduce disturbance to the soil sample. The end of the sampling tube 20 facing the base 10 is detachably connected to the base 10 for easy installation and removal; in one embodiment, the end of the sampling tube 20 facing the base 10 is threaded onto the base 10. The other end of the sampling tube 20 is provided with a first tube shoe 21. The inner diameter of the first tube shoe 21 remains constant, while the outer diameter gradually increases from bottom to top to form a tapered cutting edge. The maximum outer diameter of the first tube shoe 21 is greater than the outer diameter of the sampling tube 20, forming an outer convex ring 22. When the sampling tube 20 is pressed down, the tapered cutting edge cuts into the soft soil, pushing the remaining soft soil outwards. The outer convex ring 22 creates a gap between the outer wall of the sampling tube 20 and the soil layer, also reducing the frictional resistance caused by the soil layer on the outer wall of the sampling tube 20. The inner cavity of the sampling tube 20 is connected to the connecting cavity 11. A first piston 23 is provided in the inner cavity of the sampling tube 20. The piston rod of the first piston 23 is slidably connected to the connector 14. The piston rod extends upward through the connector 14.

[0031] The base 10 may also be detachably connected to an outer tube 30. In one embodiment, the outer tube 30 is threadedly connected to the base 10. The outer tube 30 is coaxial with the sampling tube 20 and is located outside the sampling tube 20. The length of the outer tube 30 is shorter than that of the sampling tube 20. When the sampling tube 20 is inserted into soft soil, the movement of the outer tube 30 will not disturb the soil sample already inside the sampling tube 20. With the buffer of a certain thickness of soft soil, the disturbance to the soil layer below the sampling tube 20 is also negligible. The outer tube 30 and the sampling tube 20 also form a first external cavity 31. The first external cavity 31 is open at one end away from the base 10, and the end facing the base 10 is connected to the connecting cavity 11 through a vent hole 12. Preferably, the length of the outer tube does not exceed 1 / 2 of the length of the sampling tube.

[0032] The sample breaking device 40 includes a second piston 41 and a movable sleeve 42 disposed within the first outer cavity 31. One end of the movable sleeve 42 is connected to the second piston 41, and the other end is detachably connected to a second tube shoe 43 for easy assembly and disassembly. In one embodiment, the second tube shoe 43 is threadedly connected to the movable sleeve 42. The outer wall of the movable sleeve 42 mates with the inner wall of the outer tube 30, and the inner wall of the movable sleeve 42 and the sampling tube 20 form a second outer cavity 44, which is also open at the end facing away from the base 10. The outer diameter of the second tube shoe 43 gradually increases from bottom to top, forming a tapered cutting edge, and the inner diameter of the second tube shoe 43 is greater than or equal to the outer diameter of the outer convex ring 22. When the sample breaking device 40 moves relative to the sampling tube 20, the second tube shoe 43 can pass over the outer convex ring 22.

[0033] Please refer to Figure 3 The inner wall of the second boot 43 is also provided with an annular groove, in which a limiting ring 45 and a constraint ring 46 inserted into the limiting ring 45 are provided. Both the inner wall of the limiting ring 45 and the outer wall of the constraint ring 46 are provided with L-shaped grooves, so that after the limiting ring 45 and the constraint ring 46 are inserted, they form a receiving cavity for accommodating the elastic ring 47. When the elastic ring 47 expands, it is locked within the L-shaped groove of the constraint ring 46, thus constraining the contraction of the elastic ring 47. The L-shaped groove also serves to limit the movement of the elastic ring 47. In one embodiment, the outer wall of the constraint ring 46 is provided with a plurality of protruding teeth 461 along the circumferential direction, and the protruding teeth 461 form an L-shaped groove with the outer wall of the constraint ring 46. The limiting ring 45 is provided with grooves that mate with the protruding teeth 461, and the protruding portion between two adjacent grooves forms an L-shaped groove with the inner wall of the limiting ring 45. The elastic ring 47 can be a high-elasticity annular rubber elastic rope, whose elasticity and strength are sufficient to cut soft soil in a soft plastic or fluid plastic state; in one embodiment, the diameter of the elastic ring 47 after reset is only 2~5cm.

[0034] Furthermore, the constraint ring 46 can slide in the second outer cavity 44 along the axial direction; the inner diameter of the ring groove is larger than the inner diameter of the movable sleeve 42, and the limiting ring 45 can be locked between the ring groove and the movable sleeve 42 to prevent the limiting ring 45 from moving. When the constraint ring 46 moves upward relative to the limiting ring 45, the limiting ring 45 can lock the elastic ring 47 to prevent it from moving upward.

[0035] After the sampling tube 20 is inserted into the soft soil to a predetermined depth, the sample breaking device 40 can sever most of the connection between the soil sample and the soft soil, reducing the disturbance to the soil sample when the sampling tube 20 is pulled out. Specifically, after the sampling tube 20 reaches the predetermined depth, the position of the piston rod is locked, and air pressure is increased by inflating the connecting cavity 11 and the first external cavity 31 through the connector 13, moving the sample breaking device 40 downward. Because the outer convex ring 22 widens the gap between the sampling tube 20 and the soft soil, the resistance to the downward movement of the sample breaking device 40 is small, and the air pressure inside the second external cavity 44 is stable, making it difficult for mud and water to invade from the gap between the second tube shoe 43 and the sampling tube 20; Figure 4 , 5 As shown in Figure 6, after the second boot 43 moves to the outer convex ring 22, it continues downward. The outer convex ring 22 jams the constraint ring 46, preventing it from moving further. Meanwhile, the limiting ring 45, carrying the elastic ring 47, continues to move downward. After the constraint ring 46 completely disengages from the limiting ring 45, the elastic ring 47 is located on the outer wall of the first boot 21. At this time, the elastic ring 47 is still in an expanded state and has lost the constraint of the constraint ring 46 on its contraction. Under the combined action of inertia, elasticity, and the conical cutting edge structure of the first boot, the elastic ring 47 slides downward along the outer wall of the first boot 21 until it passes the cutting edge and continues to contract. Since the soft soil in the soft plastic or fluid plastic state has low shear strength, the contraction of the elastic ring 47 is sufficient to sever most of the connection between the soil sample and the soft soil. In addition, since the sampling tube 20 has already separated the soil sample from the soft soil, the movement of the sample cutting device 40 will not cause disturbance to the soil sample in the sampling tube.

[0036] In one embodiment, the diameter of the elastic ring 47 after resetting is 4 cm. Taking the TG100 sampling tube as an example, its outer diameter is 100 mm and its inner diameter is 95 mm. When the elastic ring 47 contracts to balance the elastic force and the soil sample resistance, about 78.5% of the cross-sectional area of ​​the soil sample is cut off, making it easier to pull out the soil sample and greatly reducing the disturbance to the soil sample as a whole when pulling it out.

[0037] Preferably, the inner wall of the limiting ring 45 is also provided with a latch to fix one side of the elastic ring 47, which makes it easier to adjust the contraction position of the elastic ring 47 and retract the elastic ring 47.

[0038] Preferably, please refer to Figure 3 The constraint ring 46 is further provided with an extension 462 that is interference-fitted with the inner wall of the second tube shoe 43. The friction between the two enhances the stability of the constraint ring 46, and when the external thrust exceeds the friction, the constraint ring 46 can move upward relative to the limiting ring 45. The extension 462 can also be inserted between the second tube shoe 43 and the sampling tube 20, reducing the gap between them and further reducing the risk of mud and water intrusion. The outer wall of the extension 462 is provided with a positioning protrusion, which engages with the step of the second tube shoe 43 for easy installation.

[0039] Preferably, the outer wall of the sampling tube 20 is further provided with a venting groove 24, which is covered by the outer tube 30. The position of the venting groove 24 should ensure that when the second piston 41 moves downward to the venting groove 24, the second tube shoe 43 is near the first tube shoe 21, and the constraint ring 46 has lost its constraint on the contraction of the elastic ring 47. Due to the depressurization of the venting groove 24, the air pressure in the first external cavity decreases, and the sampling device 40 stops moving under the resistance of soft soil when it moves to the venting groove 24. The length of the venting groove 24 is greater than the thickness of the second piston 41, and a gap is provided between the inner wall of the constraint ring 46 and the sampling tube 20.

[0040] Please refer to Figure 7 When the second piston moves to the ventilation groove 24, the gas enters the second external cavity 44 through the ventilation groove 24 and then sprays out from the gap between the second tube shoe 43 and the first tube shoe 21 to eliminate the pressure difference between the area near the first tube shoe 21 and the external environment. This makes it easier to pull out the sampling tube 20, and will not cause soil disturbance due to negative pressure at the bottom of the sampling tube, nor will it cause the soil sample to fall out of the sampling tube.

[0041] Example 2

[0042] The present invention also provides a method for using an exploration and sampling device, comprising the following steps: S1. Assemble the sampling device. Expand the elastic ring 47 and fit it into the L-shaped groove of the constraint ring 46. Then, insert the constraint ring 46 onto the limiting ring 45, and then insert the limiting ring 45 into the annular groove of the second tube shoe 43. Install the second tube shoe 43 onto the movable sleeve 42. Slide the movable sleeve 42 and the second piston 41 onto the sampling tube 20 from the end away from the first tube shoe. Finally, connect the sampling tube 20 and the outer tube 30 to the base 10 in sequence.

[0043] S2, Connect the connector 13 to the ventilation pipe. The ventilation pipe is connected to the air inlet pipe and the air outlet pipe through a three-way valve. The air inlet pipe is connected to an air pump. Both the air inlet pipe and the air outlet pipe are equipped with shut-off valves.

[0044] S3, open the exhaust pipe shut-off valve, lower the first piston 23 until it is flush with the bottom port of the sampling tube 20, and move the movable sleeve 42 to the top, as shown. Figure 2 As shown.

[0045] S4. Drill a soil sampling hole at the sampling point, clean the sediment at the bottom of the hole, place the bottom end of the sampling tube 20 at the bottom of the hole, and use the locking device to lock the piston rod to fix the position of the first piston 23 relative to the sampling hole; open the exhaust pipe shut-off valve, and use the driving device to apply static pressure to the base 10 to continuously press the sampling device into the soft soil at an appropriate speed until the first preset depth. The locking device and driving device can refer to the locking device and driving device used in the sampling of existing fixed piston thin-walled soil samplers.

[0046] S5, close the exhaust pipe shut-off valve, open the air inlet pipe shut-off valve and air pump, press down the sample cutting device 40 to the second predetermined depth, stop the air pump, close the air inlet pipe shut-off valve, the outer convex ring of the first tube shoe separates the constraint ring from the limit ring, and the elastic ring automatically contracts to cut off most of the soil column in the sampling tube.

[0047] S6, pull out the sampling device, taking out the soil sample. During the pull-out, the position of the first piston remains relative to the soil sampling tube.

[0048] Example 3

[0049] The present invention also provides a method for using an exploration and sampling device, comprising the following steps: S1. Assemble the sampling device. Expand the elastic ring 47 and fit it into the L-shaped groove of the constraint ring 46. Then, insert the constraint ring 46 onto the limiting ring 45, and then insert the limiting ring 45 into the annular groove of the second tube shoe 43. Install the second tube shoe 43 onto the movable sleeve 42. Slide the movable sleeve 42 and the second piston 41 onto the sampling tube 20 from the end away from the first tube shoe. Finally, connect the sampling tube 20 and the outer tube 30 to the base 10 in sequence.

[0050] S2, Connect the connector 13 to the ventilation pipe. The ventilation pipe is connected to the air inlet pipe and the air outlet pipe through a three-way valve. The air inlet pipe is connected to an air pump. Both the air inlet pipe and the air outlet pipe are equipped with shut-off valves.

[0051] S3, open the exhaust pipe shut-off valve, lower the first piston 23 to be flush with the bottom port of the sampling tube 20, and move the movable sleeve 42 to the top.

[0052] S4. Drill a soil sampling hole at the sampling point, clean the sediment at the bottom of the hole, place the bottom end of the sampling tube 20 at the bottom of the hole, and use the locking device to lock the piston rod to fix the position of the first piston 23 relative to the sampling hole; open the exhaust pipe shut-off valve, and use the driving device to apply static pressure to the base 10 to continuously press the sampling device into the soft soil at an appropriate speed until the first preset depth. The locking device and driving device can refer to the locking device and driving device used in the sampling of existing fixed piston thin-walled soil samplers.

[0053] S5, close the exhaust pipe shut-off valve, open the air inlet pipe shut-off valve and air pump, press down the sample cutting device 40 to the second predetermined depth, stop the air pump, close the air inlet pipe shut-off valve, the outer convex ring of the first tube shoe separates the constraint ring from the limit ring, and the elastic ring automatically contracts to cut off most of the soil column in the sampling tube.

[0054] S6, pull out the sampling device, taking out the soil sample. During pull-out, the position of the first piston remains relative to the sampling tube. Turn on the air pump and the air inlet shut-off valve to continue air intake. The gas enters the bottom of the sampling tube through the first external cavity, the ventilation slot, and the second external cavity, reducing the pressure difference between the bottom of the sampling tube and the outside environment. After pull-out, turn off the air pump and close the air inlet shut-off valve.

[0055] The above describes one or more embodiments of the present invention in a relatively specific and detailed manner, but it should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A sampling device suitable for soft soil exploration, characterized in that, include: The base (10) is provided with a connecting cavity (11) and a connector (13) communicating with the connecting cavity (11). A sampling tube (20) is provided. One end of the sampling tube (20) is detachably connected to the base (10), and the other end is provided with a first tube shoe (21). The outer wall of the first tube shoe (21) is provided with an outer protruding ring (22). The inner cavity of the sampling tube (20) is connected to the connecting cavity (11). The inner cavity of the sampling tube (20) is provided with a first piston (23). The piston rod of the first piston (23) is slidably connected to the base (10). The outer tube (30) is detachably connected to the base (10). The length of the outer tube (30) is shorter than the length of the sampling tube (20). The outer tube (30) is located outside the sampling tube (20). The outer tube (30) and the sampling tube (20) form a first external cavity (31). The first external cavity (31) is connected to the connecting cavity (11). The sampling device (40) includes a second piston (41) disposed within the first external cavity (31) and a movable sleeve (42). One end of the movable sleeve (42) is connected to the second piston (41), and the other end is detachably connected to a second tube shoe (43). The inner diameter of the second tube shoe (43) is greater than or equal to the outer diameter of the outer convex ring (22). The outer wall of the movable sleeve (42) fits with the inner wall of the outer tube (30), and the movable sleeve (42) and the sampling tube (20) form a second external cavity (44). The inner wall of the second tube shoe (43) also... An annular groove is provided, in which a limiting ring (45) and a constraint ring (46) inserted into the limiting ring (45) are provided. The limiting ring (45) is locked between the annular groove and the movable sleeve (42). The constraint ring (46) can slide in the second external cavity (44) along the axial direction. The inner wall of the limiting ring (45) and the outer wall of the constraint ring (46) are both provided with L-shaped grooves, so that the limiting ring (45) and the constraint ring (46) form a receiving cavity for accommodating the elastic ring (47). The elastic ring (47) is locked in the L-shaped groove of the constraint ring (46).

2. The exploration and sampling device for soft soil according to claim 1, characterized in that, The length of the outer tube (30) does not exceed 1 / 2 of the length of the sampling tube (20).

3. The exploration and sampling device for soft soil according to claim 1, characterized in that, The outer diameter of the first tube shoe (21) gradually increases from bottom to top to form a tapered cutting edge, and the maximum diameter of the first tube shoe (21) is greater than that of the sampling tube (20) to form the outer convex ring (22).

4. The exploration and sampling device suitable for soft soil according to claim 1, characterized in that, The outer wall of the sampling tube (20) is also provided with a ventilation groove (24), which is covered by the outer tube (30), and the length of the ventilation groove (24) is greater than the thickness of the second piston (41); the inner wall of the constraint ring (46) is provided with a gap from the sampling tube (20).

5. A sampling device for soft soil exploration according to claim 1, characterized in that, The outer wall of the constraint ring (46) is provided with a plurality of protruding teeth (461) along the circumferential direction, and the limiting ring (45) is provided with a groove that cooperates with the protruding teeth (461).

6. The exploration and sampling device for soft soil according to claim 1, characterized in that, The constraint ring (46) is also provided with an extension (462) that is interference-fitted with the inner wall of the second tube shoe (43), and the outer wall of the extension (462) is provided with a positioning protrusion.

7. The exploration and sampling device for soft soil according to claim 1, characterized in that, The inner wall of the limiting ring (45) is also provided with a latch to fix one side of the elastic ring (47).

8. The exploration and sampling device for soft soil according to claim 1, characterized in that, The elastic ring (47) has a diameter of 2-5 cm after being reset.

9. A method of using the exploration and sampling device as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1, after expanding the elastic ring, it is fitted into the L-shaped groove of the constraint ring, then the constraint ring is inserted into the limiting ring, then the limiting ring is inserted into the ring groove of the second tube shoe, the second tube shoe is installed on the movable sleeve, the movable sleeve and the second piston are fitted onto the sampling tube, and finally the sampling tube and the outer tube are connected to the base in sequence. S2, connect the connector to the ventilation pipe, the ventilation pipe is connected to the air inlet pipe and the air outlet pipe respectively through the three-way valve, the air inlet pipe is connected to the air pump, and both the air inlet pipe and the air outlet pipe are equipped with shut-off valves; S3, open the exhaust pipe shut-off valve, lower the first piston to be flush with the bottom port of the sampling tube, and move the movable sleeve to the top; S4, place the bottom of the sampling tube at the sampling point, lock the piston rod, open the exhaust pipe shut-off valve, apply static pressure to the base to press the sampling device into the soft soil until the first preset depth; S5, close the exhaust pipe shut-off valve, open the air inlet pipe shut-off valve and air pump, press the sample cutting device down to the second predetermined depth, the air pump stops, close the air inlet pipe shut-off valve, the outer convex ring of the first tube shoe separates the constraint ring from the limit ring, and the elastic ring automatically contracts to cut off most of the soil column in the sampling tube. S6, pull out the sampling device and take out the soil sample.

10. The method of use according to claim 9, characterized in that, Step S6 also includes continuing to introduce air when pulling out the tube. The gas enters the bottom of the sampling tube through the first external cavity, the ventilation groove, and the second external cavity, thereby reducing the pressure difference between the bottom of the sampling tube and the outside.

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