CN217211485U - Soil sampling device capable of keeping initial stress state of sample - Google Patents

Abstract

The utility model discloses a can keep sample initial stress state's soil sampling device, include: the axial force measuring component, the axial pressure maintaining component, the radial pressure maintaining component, the sampling component and the supporting base component are arranged on the base; the axial force measuring assembly, the axial pressure maintaining assembly, the sampling assembly and the supporting base assembly are sequentially arranged along the axial direction; the force measuring rod of the axial force measuring assembly is axially arranged and in contact connection with the upper soil pressing rod of the axial pressure maintaining assembly, and the radial top pressure of the upper soil pressing rod is connected with a pressing bolt; the air bag of the radial pressure maintaining assembly is radially arranged in the soil sampling cutter of the sampling assembly in an encircling manner, and is externally connected with a fluid pressure source assembly; the supporting base component is in butt joint with the bottom of the soil sampling cutter. The utility model discloses an initial stress state of sample in the sample process is unchangeable, and can conveniently directly use the sample on the triaxial test instrument, directly carries out triaxial shear test.

Description

Soil sampling device capable of keeping initial stress state of sample

Technical Field

The utility model belongs to the technical field of soil body engineering nature research and geotechnical engineering reconnaissance soil sample of in-process, concretely relates to can keep sample initial stress state's soil sampling device.

Background

In the soil engineering property research and geotechnical engineering investigation work, a required soil sample needs to be taken out from a specific depth position of a specific site, and analysis data such as the strength and deformation characteristics of a soil body at the sampling depth can be obtained by analyzing characteristics including mechanical properties and the like of the soil sample, so that the soil sample is a foundation for researching the soil engineering properties and provides a corresponding basis for the design of engineering buildings.

The triaxial soil shearing equipment is a common soil mechanical property testing instrument, and the size of a test sample is mostly a cylindrical soil column with the diameter of 39.1mm and the height of 80 mm.

In the existing sampling technology, a groove detecting method and a well detecting method are mostly adopted for sampling, namely, a groove detecting method or a well detecting method is adopted for excavating a groove detecting method or a well detecting method at a specified position, a block-shaped soil sample is excavated at the bottom or the side wall of the groove detecting method or the well detecting method, then a large-volume soil sample is cut in a laboratory, and a soil sample with required specification and size is obtained after cutting.

In the existing sampling mode, in the process of excavating and indoor cutting of a block soil sample, the original initial stress state of the soil sample is lost, even if the soil sample is restored to the initial stress state in the test process, the property of the soil sample is changed due to the processes of pressure relief and pressurization, and the data of the actual state has large deviation, so that a reliable basis is difficult to provide for the research of soil engineering properties.

SUMMERY OF THE UTILITY MODEL

To the defect that exists among the above-mentioned prior art, the utility model discloses a can keep sample initial stress state's soil sampling device and sampling method, the utility model discloses a sample in-process soil sample's initial stress state is unchangeable, and can conveniently directly use soil sample on the triaxial apparatus, directly carries out triaxial shear test.

With the attached drawings, the technical scheme of the utility model is as follows:

soil sampling device that can keep sample initial stress state includes: the device comprises an axial force measuring component 1, an axial pressure maintaining component 2, a radial pressure maintaining component 3, a sampling component 4 and a supporting base component 5;

the axial force measuring component 1, the axial pressure maintaining component 2, the sampling component 4 and the supporting base component 5 are sequentially arranged along the axial direction;

the force measuring rod 101 of the axial force measuring component 1 is axially arranged and in contact connection with the upper soil pressing rod 202 of the axial pressure maintaining component 2, and the radial top pressure of the upper soil pressing rod 202 is connected with a pressing bolt 203;

the air bag 301 of the radial pressure maintaining assembly 3 is radially and annularly arranged in the soil sampling knife 401 of the sampling assembly 4, and the air bag 301 is externally connected with a fluid pressure source assembly;

the supporting base assembly 5 is installed at the bottom of the soil sampling knife 401 in a butt joint mode.

Further, the axial force measuring assembly 1 further comprises: a force measuring rod supporting seat 102 and a force measuring meter 103;

the force measuring rod 101 is vertically and movably connected to the force measuring rod supporting seat 102 through threads;

the force gauge 103 is mounted on the force bar 101.

Further, the axial pressure maintaining assembly 2 further comprises: an upper pressure lever support base 201;

the upper pressure bar supporting seat 201 is fixedly connected to the bottom of the force measuring bar supporting seat 102 of the axial force measuring assembly 1 through threads;

the upper soil compacting rod 202 is vertically and slidably connected to the pressure rod supporting seat 201, the top of the upper soil compacting rod 202 corresponds to the bottom of the force measuring rod 101, and scale marks are arranged on the outer side of the upper soil compacting rod 202;

the compression bolt 203 is vertically connected to the side wall of the upper compression bar supporting seat 201 through threads, and the end of the compression bolt 203 is in contact connection with the upper soil compression bar 202 in the pressure regulating chamber.

Further, the fluid pressure source assembly comprises: a pipeline switch 303, a pressure storage tank 304 and a pressure maintaining air pump 305;

a connecting port of the air bag 301 is connected with a lower connecting port of the pressure storage tank 304 through a pipeline, and the pipeline switch 303 is arranged on a connecting pipeline between the pressure storage tank 304 and the air bag 301;

the pressure medium in the pressure storage tank 304 is water;

the upper connection port of the pressure storage tank 304 is connected with an external pressure maintaining air pump 305 through a pipeline.

Further, the radial pressure maintaining assembly 3 further comprises: an airbag support sleeve 302;

the air bag support sleeve 302 is sleeved on the inner side of the air bag 301, and the air bag support sleeve 302 moves upwards synchronously with the upper soil compacting rod 202.

Furthermore, the cutter head at the bottom of the soil sampling cutter 401 is conical, an axial soil sampling channel is arranged in the center of the soil sampling cutter 401 in a penetrating mode, the inner diameter of the soil sampling channel is equivalent to the outer diameter of a soil sample to be sampled, and an annular cylindrical air bag mounting groove is formed in the inner side wall of the middle section of the soil sampling channel of the soil sampling cutter 401.

Further, the sampling assembly 4 further comprises: a soil breaking knife 402;

a soil breaking slot is horizontally and transversely formed in the side wall of the lower end of the soil sampling cutter 401, and the sheet-shaped soil breaking cutter 402 is inserted into the soil breaking slot.

Further, the support base assembly 5 includes: a lower soil compacting rod 501 and a lower rod base 502;

the lower pressure rod base 502 is in threaded connection with the bottom of the soil sampling cutter 401;

the lower soil compacting rod 501 is vertically and movably connected to the lower pressing rod base 502 through threads, a supporting seat is arranged at the bottom of the lower soil compacting rod 501, and the bottom of the lower pressing rod base 502 is supported on the supporting seat at the bottom of the lower soil compacting rod 501 along with the upward movement of the lower soil compacting rod 501 relative to the lower pressing rod base 502.

Compared with the prior art, the beneficial effects of the utility model reside in that:

1. soil sampling device, through the dynamometry subassembly on the axial direction of soil sample, the axial force of giving the soil sample is applyed along the axial to the soil sample on the preset to be equipped with clamp bolt and soil sample down, ensure to take out and remain initial axial stress state all the time in the axial of soil sample.

2. Soil sampling device is through embracing the gasbag that sets up in the sword inboard of fetching earth to be equipped with pressurize mechanism, ensure that the footpath of the soil sample that takes out remains initial radial stress state all the time.

3. Soil sampling device accomplishes soil sample back, can be directly with the axial force application end of triaxial apparatus and connect on last firming pole to on the base of triaxial test equipment is arranged in to the firming pole down, realize directly applying the axial force of test through last firming pole, still can directly be linked together triaxial test equipment's hydraulic source with the gasbag, realize through the gasbag to soil sample direct application confined pressure, promptly sampling device can directly use on the triaxial apparatus, when convenient the test, avoids removing soil sample and causes the change of soil sample stress state, influences measured data's reliability.

Drawings

Fig. 1 is a schematic structural view of a soil sampling device capable of maintaining an initial stress state of a sample according to the present invention;

fig. 2 is a schematic structural diagram of the soil sampling device capable of maintaining the initial stress state of the sample when the pressure adjustment is completed and the sampling is ready to be started;

fig. 3a is a schematic structural diagram of a soil sampling device (without a radial pressure source) according to the present invention in a soil sampling state;

FIG. 3b is an enlarged partial schematic view of the soil sampling device of FIG. 3a (without the radial pressure source);

FIG. 4 is a schematic structural diagram of the soil sampling device (including a radial pressure source) according to the present invention in a soil sampling state;

fig. 5 is a schematic structural view of the soil sampling device of the present invention cutting off the sample by the soil cutter after soil sampling is completed;

fig. 6 is a schematic structural view of the soil sampling device according to the present invention supporting the bottom of the soil sample by the lower soil pressing rod after the soil sampling device cuts off the sample;

fig. 7 is a schematic structural view showing that after the soil sampling device of the present invention finishes sampling, the lower soil pressing rod pushes the soil sample upwards and supports the soil sample on the base of the lower soil pressing rod;

in the figure:

1-an axial force measuring component, 2-an axial pressure maintaining component and 3-a radial pressure maintaining component,

4-a sampling assembly, 5-a support base assembly;

101-a force measuring rod, 102-a force measuring rod supporting seat and 103-a force measuring meter;

201-upper pressure bar supporting seat, 202-upper soil pressing bar, 203-pressure bolt;

301-air bag, 302-air bag supporting sleeve 303-pipeline switch,

304-pressure storage tank, 305-pressure maintaining air pump;

401-soil sampling knife, 402-soil breaking knife;

501-pressing soil rod, 502-pressing rod base.

Detailed Description

For clear and complete description of the technical solution and the specific working process of the present invention, the following embodiments are provided in conjunction with the accompanying drawings of the specification:

in the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present application, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

The present embodiment discloses a soil sampling device capable of maintaining an initial stress state of a sample, as shown in fig. 1, the soil sampling device includes: the axial force measuring component 1, the axial pressure maintaining component 2, the radial pressure maintaining component 3, the sampling component 4 and the supporting base component 5.

The axial force measuring assembly 1 comprises: a force measuring rod 101, a force measuring rod supporting seat 102 and a force measuring meter 103; wherein:

the force measuring rod 101 vertically penetrates through a top plate of the force measuring rod supporting seat 102 and is in threaded connection with the force measuring rod supporting seat 102, and the force measuring rod 101 axially and linearly moves relative to the force measuring rod supporting seat 102 along with the rotation of the force measuring rod 101 relative to the force measuring rod supporting seat 102; the force meter 103 is mounted on the force measuring rod 101 and is used for measuring the axial pressure received by the force measuring rod 101.

The axial pressure maintaining assembly 2 comprises: an upper pressure rod supporting seat 201, an upper soil pressure rod 202 and a pressure bolt 203; wherein:

the upper pressure rod supporting seat 201 is axially arranged at the bottom of the force measuring rod supporting seat 102, and the top of the upper pressure rod supporting seat 201 is fixedly connected with the bottom of the force measuring rod supporting seat 102 through threads; the upper soil pressing rod 202 vertically penetrates through the top plate of the pressing rod supporting seat 201 and the partition plate arranged in parallel in the middle, and freely slides in the axial direction relative to the top plate and the partition plate of the pressing rod supporting seat 201; an upper pressure head at the top of the upper soil pressing rod 202 penetrates through a top plate of the pressure rod support seat 201 and then extends into the force measuring rod support seat 102, a positioning groove matched with the bottom of the force measuring rod 101 is formed in the top surface of the upper pressure head of the upper soil pressing rod 202, and the positioning groove axially faces the bottom of the force measuring rod 101; the outer side of the upper soil compacting rod 202 is provided with scale marks along the axial direction, and the distance of the upper soil compacting rod 202 moving along the axial direction can be identified through prime number scale marks;

the compression bolt 203 vertically penetrates through the side wall of the upper compression rod supporting seat 201 and extends into a pressure regulating cavity formed between a top plate of the upper compression rod supporting seat 201 and a middle partition plate, the compression bolt 203 is in threaded connection with the side wall of the upper compression rod supporting seat 201, the end part of the compression bolt 203 is in contact connection with the upper soil compression rod 202 in the pressure regulating cavity, the length of the compression bolt 203 screwed into the upper compression rod supporting seat 201 is regulated, the pressure between the compression bolt 203 and the upper soil compression rod 202 is further controlled, and finally the axial force applied to the upper soil compression rod 202 in axial movement relative to the upper compression rod supporting seat 201 is controlled; the bottom of going up soil bar 202 is equipped with the top board, the size shape of top board is the same 39.1mm circular with the top size shape of waiting to get the soil sample.

The radial pressure maintaining assembly 3 includes: an air bag 301, an air bag support sleeve 302, a pipeline switch 303, a pressure storage tank 304 and a pressure maintaining air pump 305; wherein:

the air bag 301 is arranged on the inner side of the soil sampling cutter 401 in a 360-degree surrounding manner, and the axial length of the air bag 301 is not less than that of a soil sample to be sampled; the air bag supporting sleeve 302 is sleeved on the inner side of the air bag 301, and the bottom end of the air bag supporting sleeve 302 is positioned on the top end face of the upper pressure plate at the bottom of the upper soil pressing rod 202, that is, as the upper soil pressing rod 202 moves upwards along the axial direction, the upper pressure plate at the bottom of the upper soil pressing rod 202 drives the air bag supporting sleeve 302 to move upwards relative to the air bag 301 along the axial direction;

a connecting port of the air bag 301 is connected with a lower connecting port of the pressure storage tank 304 through a pipeline, the pipeline switch 303 is installed on a connecting pipeline between the pressure storage tank 304 and the air bag 301, and the pipeline switch 303 adopts a manual switch; the pressure medium in the pressure storage tank 304 is water; the upper connection port of the pressure storage tank 304 is connected with an external pressure maintaining air pump 305 through a pipeline, the pressure of air entering the pressure storage tank 304 is controlled through the pressure maintaining air pump 305, the pressure of water flowing out of the pressure storage tank 304 and flowing into the air bag 301 through the pipeline switch 303 is adjusted through the pressure of air entering the pressure storage tank 304, and further the radial pressure applied outwards through the air bag 301 is controlled.

The sampling assembly 4 comprises: a soil sampling knife 401 and a soil breaking knife 402; wherein:

the soil sampling cutter 401 is axially mounted at the bottom of the upper pressure rod supporting seat 201, the soil sampling end at the bottom of the soil sampling cutter 401 is conical so that the soil sampling cutter can conveniently extend into soil for sampling, an axial soil sampling channel is formed in the center of the soil sampling cutter 401 in a penetrating mode, and the inner diameter size of the soil sampling channel is equivalent to the outer diameter size of a soil sample to be sampled, namely 39.1 mm; an annular cylindrical air bag mounting groove is formed in the inner side wall of the middle section of the soil taking channel of the soil taking knife 401 and used for mounting the air bag 301;

the side wall of the lower end of the soil sampling knife 401 is horizontally and transversely provided with a soil breaking slot, the transverse size of the soil breaking slot is larger than the outer diameter size of a soil sample to be sampled, after the soil sample enters the soil sampling channel of the soil sampling knife 401 to a specified position, the flaky soil breaking knife 402 is inserted into the soil breaking slot of the soil sampling knife 401, the soil sample in the soil sampling channel of the soil sampling knife 401 is cut off, and the soil sample is conveniently taken out.

The support base assembly 5 comprises: a lower soil compacting rod 501 and a lower rod base 502; wherein:

the lower pressure rod base 502 is axially arranged at the lower end of the soil sampling cutter 401, and the lower pressure rod base 502 is assembled and connected with the bottom of the soil sampling cutter 401 through threads;

the lower soil compacting rod 501 vertically penetrates through the lower pressing rod base 502 along the axial direction and is in threaded fit connection with the lower pressing rod base 502, and as the lower soil compacting rod 501 rotates relative to the lower pressing rod base 502, the lower soil compacting rod 501 linearly moves relative to the lower pressing rod base 502 along the axial direction; the top of lower firming pole 501 is equipped with the holding down plate, the size and shape of holding down plate and the same 39.1mm circular of the bottom size and shape of waiting to sample soil, the bottom of holding down pole 501 is equipped with the supporting seat, just the supporting seat is located depression bar base 502 bottom, works as the removal is twisted upwards to depression bar 501 for depression bar base 502, and contacts with the soil sample bottom that has cut off, along with the removal is twisted upwards to depression bar base 502 to lower firming pole 501 continues to move for depression bar base 502, pushes away soil sample along the passageway of fetching soil of borrowing knife 401 inboard upwards down, support on the supporting seat of holding down pole 501 bottom that the bottom of depression bar base 502 is firm to realize the firm support to its above spare part and inside soil sample.

Soil sampling device's concrete sampling process step as follows:

the method comprises the following steps: digging an exploration well or an exploration groove at the soil taking place to the depth required by sampling, and leveling the bottom;

step two: a pipeline switch 303 on a connecting pipeline between the pressure storage tank 304 and the air bag 301 is opened, a pressure maintaining air pump 305 is adjusted, the pressure in the pressure storage tank 304 is controlled to be increased to a preset radial pressure, and meanwhile, the pressure in the air bag 301 also reaches the preset radial pressure;

the preset radial pressure is the horizontal pressure of soil at the soil taking depth measured by a side pressure test;

step three: adjusting the length of the compression bolt 203 screwed into the upper compression bar supporting seat 201 to control the compression bolt 203 to act on the upper compression bar 202 and adjust the resistance of the upper compression bar 202 to move along the axial direction, meanwhile, screwing the force measuring bar 101 to make the top positioning groove of the upper compression bar 202 contact with the bottom positioning groove of the upper force measuring bar 101 and transmit the axial pressure until the force measuring meter 103 measures that the reverse axial force applied by the upper compression bar 202 to the force measuring bar 101 reaches the preset axial pressure, and keeping the position of the compression bolt 203 relatively fixed;

the preset axial pressure is obtained by calculating the soil gravity and the sampling depth;

step four: as shown in fig. 2, 3a and 3b, after the position of the hold-down bolt 203 is adjusted, the axial force-measuring assembly 1 including the force-measuring rod 101, the force-measuring rod support 102 and the force-measuring gauge 103 is removed from the device, and the soil-sampling knife 401 is inserted into the soil perpendicular to the sampling bottom surface;

step five: as shown in fig. 4, as the cutter head at the bottom of the soil sampling knife 401 is pressed into the soil, a columnar soil sample enters the soil sampling channel inside the soil sampling knife 401 through the cutter head, and as the soil sample enters, the upper soil pressing rod 202 moves upward along the axial direction under the pushing action of the movement of the soil sample and takes the air bag supporting sleeve 302 out of the middle of the air bag 301, the soil sample smoothly enters the middle position of the air bag 301 and is surrounded and wrapped by the air bag 301 which keeps a preset radial pressure outward in a 360-degree manner, because the forces are mutual, in the process that the upper soil pressing rod 202 is pushed upward by the soil sample to operate, the soil sample is always subjected to the preset axial pressure applied by the upper soil pressing rod 202, and by recognizing the scale on the upper soil pressing rod 202, when the upper soil pressing rod 202 moves to a preset distance along the axial direction under the action of the soil sample, that is, when the length of the soil sample reaches the preset sampling length, the soil sampling knife 401 stops moving;

step six: as shown in fig. 5, soil outside the soil sampling blade 401 is cleaned, the soil breaking blade 402 is inserted into the soil breaking slot of the soil sampling blade 401, and the soil sample in the soil sampling channel of the soil sampling blade 401 is cut off;

step seven: as shown in fig. 6, the soil sampling knife 401 is taken out of the soil, the excess soil on the outer side is cleaned and removed, the lower pressure rod base 502 is screwed and fixed at the bottom of the soil sampling knife 401 in a butt joint manner, the soil pressing rod 501 is further screwed and removed until the lower pressure plate at the top of the soil pressing rod 501 is pressed on the soil breaking knife 402, and then the soil breaking knife 402 is taken out of the soil breaking slot of the soil sampling knife 401;

step eight: as shown in fig. 7, after the soil breaking knife 402 is taken out, the lower pressing plate on the top of the lower pressing rod 501 directly presses the bottom of the cylindrical soil sample, and the soil pressing rod 501 is further screwed down until the bottom of the lower pressing rod base 502 is stably supported on the supporting seat at the bottom of the lower pressing rod 501, at this time, the soil sample is just located in the middle of the air bag 301, and the soil sample is kept in an initial stress state.

Through above-mentioned embodiment one sampling device obtain behind the soil sample, can be connected the sampling device that is equipped with the soil sample directly with the triaxial apparatus, test its inside soil sample, wherein, the axial force application end of triaxial apparatus is connected on last soil pressing rod, and will push down on soil pressing rod bottom sprag seat arranges the base of triaxial apparatus in, realize carrying out shear test through the axial force that last soil pressing rod directly applys the test, still directly be linked together triaxial test equipment's hydraulic source with the gasbag directly, realize directly applying radial pressure to the soil sample through the gasbag, sampling device directly uses on the triaxial apparatus, when convenient the test, avoids removing the soil sample and causes soil sample stress state change, influences measured data's reliability.

While embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations of the above embodiments may be made by those of ordinary skill in the art without departing from the scope of the present invention.

The above description is intended to illustrate the embodiments of the present invention, and not to limit the scope of the invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.

Claims (8)

1. Can keep the soil sampling device of sample initial stress state, its characterized in that:

the method comprises the following steps: the device comprises an axial force measuring component (1), an axial pressure maintaining component (2), a radial pressure maintaining component (3), a sampling component (4) and a supporting base component (5);

the axial force measuring component (1), the axial pressure maintaining component (2), the sampling component (4) and the supporting base component (5) are sequentially arranged along the axial direction;

a force measuring rod (101) of the axial force measuring component (1) is axially arranged and in contact connection with an upper soil pressing rod (202) of the axial pressure maintaining component (2), and a pressing bolt (203) is radially pressed and connected to the upper soil pressing rod (202);

an air bag (301) of the radial pressure maintaining assembly (3) is radially arranged in an earth taking knife (401) of the sampling assembly (4) in an encircling manner, and the air bag (301) is externally connected with a fluid pressure source assembly;

the supporting base component (5) is installed at the bottom of the soil sampling cutter (401) in a butt joint mode.

2. A soil sampling device as claimed in claim 1 which is capable of maintaining an initial stress state of a sample, wherein:

the axial force measuring assembly (1) further comprises: a force measuring rod supporting seat (102) and a force measuring meter (103);

the force measuring rod (101) is vertically and movably connected to the force measuring rod supporting seat (102) through threads;

the force measuring meter (103) is arranged on the force measuring rod (101).

3. A soil sampling device according to claim 1 capable of maintaining an initial stress state of a sample, wherein:

the axial pressure maintaining assembly (2) further comprises: an upper pressure lever supporting seat (201);

the upper pressure lever supporting seat (201) is fixedly connected to the bottom of a force measuring lever supporting seat (102) of the axial force measuring assembly (1) through threads;

the upper soil pressing rod (202) is vertically connected to the upper pressure rod supporting seat (201) in a sliding mode, the top of the upper soil pressing rod (202) corresponds to the bottom of the force measuring rod (101), and scale marks are arranged on the outer side of the upper soil pressing rod (202);

the compression bolt (203) is vertically connected to the side wall of the upper compression bar supporting seat (201) through threads, and the end part of the compression bolt (203) is in contact connection with the upper soil compression bar (202) in the pressure regulating cavity.

4. A soil sampling device as claimed in claim 1 which is capable of maintaining an initial stress state of a sample, wherein:

the fluid pressure source assembly comprises: a pipeline switch (303), a pressure storage tank (304) and a pressure maintaining air pump (305);

a connecting port of the air bag (301) is connected with a lower connecting port of the pressure storage tank (304) through a pipeline, and the pipeline switch (303) is arranged on a connecting pipeline between the pressure storage tank (304) and the air bag (301);

the pressure medium in the pressure storage tank (304) is water;

the upper connecting port of the pressure storage tank (304) is connected with an external pressure maintaining air pump (305) through a pipeline.

5. A soil sampling device as claimed in claim 1 or claim 4 which is capable of maintaining an initial stressed state of a sample, wherein:

the radial pressure maintaining assembly (3) further comprises: an airbag support sleeve (302);

the air bag supporting sleeve (302) is sleeved on the inner side of the air bag (301), and the air bag supporting sleeve (302) moves upwards synchronously along with the upper soil pressing rod (202).

6. A soil sampling device as claimed in claim 1 which is capable of maintaining an initial stress state of a sample, wherein:

the tool bit of the bottom of the soil sampling tool (401) is conical, an axial soil sampling channel is formed in the center of the soil sampling tool (401) in a penetrating mode, the inner diameter of the soil sampling channel is equal to the outer diameter of a soil sample to be sampled, and an annular cylindrical air bag mounting groove is formed in the inner side wall of the middle section of the soil sampling channel of the soil sampling tool (401).

7. A soil sampling device according to claim 1 or claim 6 capable of maintaining an initial stress state of a sample, wherein:

the sampling assembly (4) further comprises: a soil breaking knife (402);

a soil breaking slot is horizontally and transversely formed in the side wall of the lower end of the soil taking knife (401), and the sheet-shaped soil breaking knife (402) is inserted into the soil breaking slot.

8. A soil sampling device according to claim 1 or claim 6 capable of maintaining an initial stress state of a sample, wherein:

the support foot assembly (5) comprises: a lower soil pressing rod (501) and a lower pressing rod base (502);

the lower pressure rod base (502) is in threaded connection with the bottom of the soil sampling cutter (401);

the lower soil compacting rod (501) is vertically and movably connected onto the lower soil compacting rod base (502) through threads, a supporting seat is arranged at the bottom of the lower soil compacting rod (501), and along with the upward movement of the lower soil compacting rod (501) relative to the lower soil compacting rod base (502), the bottom of the lower soil compacting rod base (502) is supported on the supporting seat at the bottom of the lower soil compacting rod (501).

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