Soil sampling device and sampling method capable of maintaining initial stress state of sample

Abstract

The present invention discloses a soil sampling device and a sampling method capable of maintaining the initial stress state of a sample, wherein the sampling device comprises: an axial force measuring component, an axial pressure maintaining component, a radial pressure maintaining component, a sampling component and a supporting base component; the axial force measuring component, the axial pressure maintaining component, the sampling component and the supporting base component are sequentially installed along the axial direction; the force measuring rod of the axial force measuring component and the upper soil pressing rod of the axial pressure maintaining component are axially arranged and contact-connected, and the radial top-pressure connection of the upper soil pressing rod is provided with a clamping bolt; the airbag of the radial pressure maintaining component is radially encircled and installed in the soil cutting knife of the sampling component, and the airbag is externally connected to a fluid pressure source component; the supporting base component is docked and installed at the bottom of the soil cutting knife. The present invention realizes that the initial stress state of the soil sample remains unchanged during the sampling process, and the soil sample can be conveniently directly applied to a triaxial test instrument to directly conduct a triaxial shear test.

Description

Technical Field

[0001] The invention belongs to the technical field of soil sampling in the process of soil engineering property research and geotechnical engineering investigation, and particularly relates to a soil sampling device and a sampling method capable of maintaining the initial stress state of a sample. Background Art

[0002] In the study of soil engineering properties and geotechnical engineering investigations, it is necessary to take the required soil samples from a specific depth at a specific location. By analyzing the characteristics of the soil samples, including mechanical properties, analytical data such as the strength and deformation characteristics of the soil at the sampling depth can be obtained. This is the basis for studying the engineering properties of soil and also provides a corresponding basis for the design of engineering buildings.

[0003] The soil triaxial shear equipment is a commonly used instrument for testing the mechanical properties of soil. The size of the test sample is mostly a cylindrical soil column with a diameter of 39.1 mm and a height of 80 mm.

[0004] In the existing sampling technology, sampling is mostly carried out by trenching and welling, that is, a trench or well is dug at a designated location, bulk soil samples are dug from the bottom or side wall, and then the large volume of soil samples are cut in the laboratory to obtain soil samples of the required specifications and sizes.

[0005] In the above-mentioned existing sampling methods, during the process of digging block soil samples and indoor cutting, the soil samples have already lost their original initial stress state. Even if the soil samples are restored to the initial stress state during the test, the properties of the soil samples will change due to the process of decompression and pressurization, and there will be a large deviation from the data of the actual state, which makes it difficult to provide a reliable basis for the study of soil engineering properties, especially in geotechnical engineering survey work. The destruction of the initial stress state leads to deviations in the mechanical properties of the soil. In order to ensure the safety of the building, the design of the engineering building is too conservative, and the project cost increases accordingly. Summary of the invention

[0006] In view of the defects existing in the above-mentioned prior art, the present invention discloses a soil sampling device and a sampling method capable of maintaining the initial stress state of the sample. The present invention ensures that the initial stress state of the soil sample remains unchanged during the sampling process, and the soil sample can be conveniently applied directly to a triaxial instrument to directly perform a triaxial shear test.

[0007] Combined with the accompanying drawings, the technical solution of the present invention is as follows:

[0008] A soil sampling device capable of maintaining the initial stress state of a sample 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;

[0009] The axial force measuring assembly 1, the axial pressure maintaining assembly 2, the sampling assembly 4 and the supporting base assembly 5 are sequentially installed along the axial direction;

[0010] The force measuring rod 101 of the axial force measuring assembly 1 is axially arranged and contact-connected with the upper soil pressing rod 202 of the axial pressure maintaining assembly 2, and the upper soil pressing rod 202 is radially pressed and connected with a clamping bolt 203;

[0011] The airbag 301 of the radial pressure-maintaining component 3 is installed in a radially embracing shape inside the soil-taking knife 401 of the sampling component 4, and the airbag 301 is externally connected to a fluid pressure source component;

[0012] The support base assembly 5 is docked and installed at the bottom of the soil cutting knife 401.

[0013] Furthermore, the axial force measuring assembly 1 further comprises: a force measuring rod support seat 102 and a force measuring meter 103;

[0014] The force measuring rod 101 is vertically movably connected to the force measuring rod support seat 102 through a thread;

[0015] The force gauge 103 is installed on the force measuring rod 101 .

[0016] Furthermore, the axial pressure-maintaining assembly 2 further includes: an upper pressure rod support seat 201;

[0017] The upper pressure rod support seat 201 is threadedly fixedly connected to the bottom of the force measuring rod support seat 102 of the axial force measuring assembly 1;

[0018] The upper soil pressure rod 202 is vertically slidably connected to the pressure rod support seat 201, the top of the upper soil pressure rod 202 corresponds to the bottom of the force measuring rod 101, and a scale line is provided on the outer side of the upper soil pressure rod 202;

[0019] The clamping bolt 203 is vertically connected to the side wall of the upper pressure rod support seat 201 through a thread, and the end of the clamping bolt 203 is in contact with and connected to the upper soil pressure rod 202 in the pressure regulating chamber.

[0020] Furthermore, the fluid pressure source assembly includes: a pipeline switch 303, a pressure storage tank 304 and a pressure-maintaining air pump 305;

[0021] The connection port of the airbag 301 is connected to the lower connection port of the pressure storage tank 304 through a pipeline, and the pipeline switch 303 is installed on the connection pipeline between the pressure storage tank 304 and the airbag 301;

[0022] The pressure medium in the pressure storage tank 304 is water;

[0023] The upper connection port of the pressure storage tank 304 is connected to an external pressure-maintaining air pump 305 through a pipeline.

[0024] Furthermore, the radial pressure-maintaining assembly 3 further includes: an airbag support sleeve 302;

[0025] The airbag support sleeve 302 is sleeved on the inner side of the airbag 301 , and the airbag support sleeve 302 moves upward synchronously with the upper soil pressing rod 202 .

[0026] Furthermore, the bottom blade of the soil taking knife 401 is conical, and an axial soil taking channel is opened through the center of the soil taking knife 401. The inner diameter of the soil taking channel is equivalent to the outer diameter of the soil sample to be taken, and an annular cylindrical airbag installation groove is opened on the inner side wall of the middle section of the soil taking channel of the soil taking knife 401.

[0027] Furthermore, the sampling assembly 4 further includes: a soil cutting knife 402;

[0028] A soil cutting slot is horizontally opened on the side wall of the lower end of the soil cutting knife 401, and the sheet-shaped soil cutting knife 402 is inserted into the soil cutting slot.

[0029] Furthermore, the support base assembly 5 comprises: a down-pressing soil rod 501 and a down-pressing rod base 502;

[0030] The lower pressure rod base 502 is threadedly connected to the bottom of the soil cutting knife 401;

[0031] The lower soil pressure rod 501 is vertically movably connected to the lower soil pressure rod base 502 through a thread, and a support seat is provided at the bottom of the lower soil pressure rod 501. As the lower soil pressure rod 501 moves upward relative to the lower soil pressure rod base 502, the bottom of the lower soil pressure rod base 502 is supported on the support seat at the bottom of the lower soil pressure rod 501.

[0032] The sampling method of the soil sampling device capable of maintaining the initial stress state of the sample is as follows:

[0033] Step 1: Dig a well or trench at the sampling site to the required depth for sampling and level the bottom;

[0034] Step 2: Open and adjust the fluid pressure source assembly so that the pressure in the airbag 301 reaches a preset confining pressure;

[0035] Step 3: Adjust the length of the clamping bolt 203 screwed into the upper pressure rod support seat 201, control the clamping bolt 203 to act on the upper pressure rod 202, and adjust the resistance of the upper pressure rod 202 to move axially. At the same time, adjust the axial force measuring assembly 1 so that the reverse axial force applied by the upper pressure rod 202 to the force measuring assembly 1 reaches the preset axial pressure, and keep the clamping bolt 203 relatively fixed;

[0036] Step 4: Remove the axial force measuring assembly 1 from the device, and extend the soil cutting knife 401 into the soil perpendicular to the sampling ground surface;

[0037] Step 5: As the bottom cutter head of the soil taking cutter 401 is pressed into the soil, the columnar soil sample enters the soil taking channel inside the soil taking cutter 401 through the cutter head and pushes the upper soil pressing rod 202 upward. After the soil sample successfully enters the air bag 301, the soil taking cutter 401 stops moving;

[0038] Step 6: Cutting the soil sample in the soil cutting knife 401 by the soil cutting knife 402;

[0039] Step 7: After taking the soil cutting knife 401 out of the soil, the lower pressure rod base 502 of the supporting base assembly 5 is docked and installed at the bottom of the soil cutting knife 401, and the lower pressure rod 501 connected to the lower pressure rod base 502 by threading is pressed against the bottom of the soil sample;

[0040] Step 8: Control the lower soil pressing rod 501 to move upward until the bottom of the lower soil pressing rod base 502 is supported on the support seat at the bottom of the lower soil pressing rod 501 .

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The soil sampling device of the present invention pre-sets the axial force applied to the soil sample by the upper soil pressing rod in the axial direction through the force measuring component in the axial direction of the soil sampling, and is equipped with a clamping bolt and a lower soil pressing rod to ensure that the initial axial stress state is always maintained in the axial direction of the soil sample taken.

[0043] 2. The soil sampling device of the present invention ensures that the soil sample taken always maintains the initial radial stress state in the radial direction by embracing the air bag arranged inside the soil sampling knife and being equipped with a pressure-maintaining mechanism.

[0044] 3. After the soil sampling is completed, the soil sampling device of the present invention can directly connect the axial force applying end of the triaxial instrument to the upper soil pressing rod, and place the lower soil pressing rod on the base of the triaxial testing equipment to directly apply the axial force of the test through the upper soil pressing rod. The hydraulic source of the triaxial testing equipment can also be directly connected to the airbag to directly apply the confining pressure to the soil sample through the airbag. That is, the sampling device can be directly applied to the triaxial instrument, which is convenient for testing while avoiding changes in the stress state of the soil sample caused by moving the soil sample, which affects the reliability of the measurement data. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a schematic structural diagram of the soil sampling device capable of maintaining the initial stress state of the sample according to the present invention;

[0046] Figure 2 This is a schematic diagram of the structure of the soil sampling device capable of maintaining the initial stress state of the sample according to the present invention, when the pressure adjustment is completed and the sampling is ready to start;

[0047] Figure 3aIt is a structural schematic diagram of the soil sampling device (excluding the radial pressure source) of the present invention in the soil sampling state;

[0048] Figure 3b for Figure 3a A schematic diagram of the partially enlarged structure of the soil sampling device (excluding the radial pressure source);

[0049] Figure 4 It is a structural schematic diagram of the soil sampling device (including radial pressure source) of the present invention in the soil sampling state;

[0050] Figure 5 This is a schematic diagram of the structure of the soil sampling device of the present invention using a soil cutter to cut off the sample after the soil sampling is completed;

[0051] Figure 6 This is a schematic structural diagram of the bottom of the soil sample being supported by a downward-pressing soil rod after the soil sampling device of the present invention cuts off the sample;

[0052] Figure 7 This is a schematic diagram of the structure in which the soil sampling device of the present invention pushes the soil sample upward and is supported on the base of the soil sampling rod after sampling is completed;

[0053] In the figure:

[0054] 1- axial force measuring assembly, 2- axial pressure holding assembly, 3- radial pressure holding assembly,

[0055] 4-sampling assembly, 5-support base assembly;

[0056] 101-force measuring rod, 102-force measuring rod support seat, 103-force measuring meter;

[0057] 201-upper pressure rod support seat, 202-upper pressure rod, 203-tightening bolt;

[0058] 301-airbag, 302-airbag support sleeve 303-pipeline switch,

[0059] 304-pressure storage tank, 305-pressure maintaining air pump;

[0060] 401- soil-taking knife, 402- soil-breaking knife;

[0061] 501-soil pressure rod, 502-soil pressure rod base. DETAILED DESCRIPTION

[0062] In order to clearly and completely describe the technical solution and its specific working process of the present invention, the specific implementation methods of the present invention are as follows in conjunction with the accompanying drawings of the specification:

[0063] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0064] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0065] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0066] Embodiment 1:

[0067] This embodiment 1 discloses a soil sampling device capable of maintaining the initial stress state of the sample, such as Figure 1 As shown, the soil sampling device includes: 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.

[0068] The axial force measuring assembly 1 comprises: a force measuring rod 101, a force measuring rod support seat 102 and a force measuring meter 103; wherein:

[0069] The force measuring rod 101 vertically passes through the top plate of the force measuring rod support seat 102 and is threadedly connected to the force measuring rod support seat 102. As the force measuring rod 101 rotates relative to the force measuring rod support seat 102, the force measuring rod 101 moves axially linearly relative to the force measuring rod support seat 102. The force gauge 103 is installed on the force measuring rod 101 and is used to measure the axial pressure received by the force measuring rod 101.

[0070] The axial pressure-maintaining assembly 2 comprises: an upper pressure rod support seat 201, an upper soil pressure rod 202 and a clamping bolt 203; wherein:

[0071] The upper pressure rod support seat 201 is axially installed at the bottom of the force measuring rod support seat 102, and the top of the upper pressure rod support seat 201 is threadedly connected and fixed to the bottom of the force measuring rod support seat 102; the upper soil pressure rod 202 vertically passes through the top plate of the pressure rod support seat 201 and the partition plate arranged parallel to the middle, and slides freely axially relative to the top plate and the middle partition plate of the pressure rod support seat 201; the upper pressure head at the top of the upper soil pressure rod 202 passes through the top plate of the pressure rod support seat 201 and extends into the force measuring rod support seat 102, and a positioning groove matching the bottom of the force measuring rod 101 is opened on the top surface of the upper pressure head of the upper soil pressure rod 202, and the positioning groove is axially opposite to the bottom of the force measuring rod 101; the outer side of the upper soil pressure rod 202 is provided with scale lines along the axial direction, and the axial movement distance of the upper soil pressure rod 202 can be identified by the prime scale lines;

[0072] The clamping bolt 203 vertically passes through the side wall of the upper pressure rod support seat 201 and extends into the pressure regulating chamber formed between the top plate of the upper pressure rod support seat 201 and the middle partition plate. The clamping bolt 203 is threadedly connected to the side wall of the upper pressure rod support seat 201, and the end of the clamping bolt 203 is in contact and connected with the upper soil pressure rod 202 in the pressure regulating chamber. By adjusting the length of the clamping bolt 203 screwed into the upper pressure rod support seat 201, the pressure between the clamping bolt 203 and the upper soil pressure rod 202 is controlled, and finally the axial force exerted on the upper soil pressure rod 202 along the axial movement relative to the upper pressure rod support seat 201 is controlled; an upper pressure plate is provided at the bottom of the upper soil pressure rod 202, and the size and shape of the upper pressure plate is a 39.1mm circle that is the same as the top size and shape of the soil sample to be taken.

[0073] The radial pressure-maintaining assembly 3 includes: an airbag 301, an airbag support sleeve 302, a pipeline switch 303, a pressure storage tank 304 and a pressure-maintaining air pump 305; wherein:

[0074] The airbag 301 is installed in a 360° embracing shape inside the soil cutting knife 401, and the axial length of the airbag 301 is not less than the axial length of the soil sample to be taken; the airbag support sleeve 302 is sleeved inside the airbag 301, and the bottom end of the airbag support sleeve 302 is located on the top end surface 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 upward in the axial direction, the upper pressure plate at the bottom of the upper soil pressing rod 202 will drive the airbag support sleeve 302 to move upward in the axial direction relative to the airbag 301;

[0075] The connection port of the airbag 301 is connected to the lower connection port of the pressure storage tank 304 through a pipeline, and the pipeline switch 303 is installed on the connecting pipeline between the pressure storage tank 304 and the airbag 301. The pipeline switch 303 is 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 to the external pressure-maintaining air pump 305 through a pipeline, and the pressure of the gas entering the pressure storage tank 304 is controlled by the pressure-maintaining air pump 305. The water pressure flowing out of the pressure storage tank 304 and flowing into the airbag 301 through the pipeline switch 303 is adjusted by the gas pressure entering the pressure storage tank 304, thereby realizing the control of the radial pressure applied outward through the airbag 301.

[0076] The sampling assembly 4 includes: a soil sampling knife 401 and a soil cutting knife 402; wherein:

[0077] The soil taking knife 401 is axially mounted at the bottom of the upper pressure rod support seat 201. The soil taking end at the bottom of the soil taking knife 401 is conical, so that the soil taking knife can be inserted into the soil for sampling. An axial soil taking channel is opened through the center of the soil taking knife 401. The inner diameter of the soil taking channel is equivalent to the outer diameter of the soil sample to be taken, that is, 39.1 mm. An annular cylindrical airbag installation groove is opened on the inner side wall of the middle section of the soil taking channel of the soil taking knife 401 for installing the airbag 301.

[0078] A soil cutting slot is horizontally opened on the side wall of the lower end of the soil cutting knife 401, and the lateral dimension of the soil cutting slot is larger than the outer diameter of the soil sample to be taken. When the soil sample enters the soil taking channel of the soil cutting knife 401 to the specified position, the sheet-shaped soil cutting knife 402 is inserted into the soil cutting slot of the soil cutting knife 401 to cut off the soil sample in the soil taking channel of the soil cutting knife 401, so as to facilitate the removal of the soil sample.

[0079] The support base assembly 5 includes: a down-pressing soil rod 501 and a down-pressing rod base 502; wherein:

[0080] The lower pressure rod base 502 is axially arranged at the lower end of the soil cutting knife 401, and the lower pressure rod base 502 is connected to the bottom of the soil cutting knife 401 through threaded assembly;

[0081] The lower soil pressing rod 501 vertically passes through the lower soil pressing rod base 502 along the axial direction and is threadedly connected with the lower soil pressing rod base 502. As the lower soil pressing rod 501 rotates relative to the lower soil pressing rod base 502, the lower soil pressing rod 501 moves axially linearly relative to the lower soil pressing rod base 502. A lower pressing plate is provided on the top of the lower soil pressing rod 501. The size and shape of the lower pressing plate are the same as the size and shape of the bottom of the soil sample to be taken, which is a 39.1 mm circular shape. A support seat is provided at the bottom of the lower soil pressing rod 501, and the support seat At the bottom of the lower pressure rod base 502, when the lower pressure rod 501 is screwed upward relative to the lower pressure rod base 502 and contacts the bottom of the cut soil sample, as the lower pressure rod 501 continues to be screwed upward relative to the lower pressure rod base 502, the lower pressure rod 501 pushes the soil sample upward along the soil taking channel inside the soil taking knife 401 until the bottom of the lower pressure rod base 502 is firmly supported on the support seat at the bottom of the lower pressure rod 501, so as to achieve firm support for the components above it and the internal soil samples.

[0082] Embodiment 2:

[0083] The second embodiment discloses a sampling method of a soil sampling device capable of maintaining the initial stress state of a sample. The sampling method is implemented by using the soil sampling device described in the first embodiment. The specific sampling process steps are as follows:

[0084] Step 1: Dig a well or trench at the sampling site to the required depth for sampling and level the bottom;

[0085] Step 2: Open the pipeline switch 303 on the pipeline connecting the pressure storage tank 304 and the air bag 301, adjust the pressure-maintaining air pump 305, control the pressure in the pressure storage tank 304 to increase to a preset radial pressure, and at the same time, the pressure in the air bag 301 also reaches the preset radial pressure;

[0086] The preset radial pressure is the horizontal pressure of the soil at the soil sampling depth measured by the lateral pressure test;

[0087] Step 3: Adjust the length of the clamping bolt 203 screwed into the upper pressure rod support seat 201 to control the clamping bolt 203 acting on the upper pressure rod 202 and adjust the resistance of the upper pressure rod 202 to axial movement. At the same time, screw the force measuring rod 101 to make the top positioning groove of the upper pressure rod 202 contact with the bottom positioning groove of the upper force measuring rod 101 and transmit axial pressure until the force measuring gauge 103 measures that the reverse axial force applied by the upper pressure rod 202 to the force measuring rod 101 reaches the preset axial pressure, so as to keep the clamping bolt 203 relatively fixed;

[0088] The preset axial pressure is calculated by the soil density and sampling depth;

[0089] Step 4: If Figure 2 , Figure 3a and Figure 3b As shown, after the position of the clamping bolt 203 is adjusted, the axial force measuring assembly 1 including the force measuring rod 101, the force measuring rod support seat 102 and the force measuring meter 103 is removed from the device, and the soil sampling knife 401 is extended into the soil perpendicular to the sampling bottom surface;

[0090] Step 5: If Figure 4 As shown, as the bottom cutter head of the soil cutting knife 401 is pressed into the soil, the columnar soil sample enters the soil cutting channel inside the soil cutting knife 401 through the cutter head. As the soil sample enters, the upper soil pressing rod 202 moves upward along the axial direction under the top pressure of the soil sample, and brings the airbag support sleeve 302 out from the middle of the airbag 301. The soil sample smoothly enters the middle position of the airbag 301 and is surrounded and wrapped 360° by the airbag 301 which maintains a preset radial pressure outward. Since the force is mutual, the upper soil pressing rod 202 is always subjected to the preset axial pressure applied by the upper soil pressing rod 202 during the process of being pushed upward by the soil sample. By identifying the scale on the upper soil pressing rod 202, when the upper soil pressing rod 202 moves axially to a preset distance under the action of the soil sample, that is, when the length of the soil sample reaches the preset sampling length, the soil cutting knife 401 stops moving.

[0091] Step 6: If Figure 5 As shown, the soil outside the soil taking knife 401 is cleaned, and the soil cutting knife 402 is inserted into the soil cutting slot of the soil taking knife 401 to cut off the soil sample in the soil taking channel of the soil taking knife 401;

[0092] Step 7: If Figure 6 As shown, the soil cutting knife 401 is taken out from the soil, and the excess soil on the outside is cleaned and removed. After the lower pressure rod base 502 is fixed to the bottom of the soil cutting knife 401 by docking, screwing and fixing, the lower pressure rod 501 is further screwed until the lower pressure plate on the top of the lower pressure rod 501 presses on the soil cutting knife 402, and then the soil cutting knife 402 is taken out from the soil cutting slot of the soil cutting knife 401;

[0093] Step 8: If Figure 7 As shown, after the soil cutting knife 402 is taken out, the lower pressure plate on the top of the lower pressure rod 501 directly presses on the bottom of the cylindrical soil sample, and the lower pressure rod 501 is further screwed until the bottom of the lower pressure rod base 502 is firmly supported on the support seat at the bottom of the lower pressure rod 501. At this time, the soil sample is exactly located in the middle of the airbag 301, and the soil sample remains in the initial stress state.

[0094] After obtaining soil samples through the sampling device described in the above embodiment 1 and installing the sampling method described in the above embodiment 2, the sampling device containing the soil samples can be directly connected to the triaxial instrument to test the soil samples inside it, wherein the axial force applying end of the triaxial instrument is connected to the upper soil pressure rod, and the bottom support seat of the lower soil pressure rod is placed on the base of the triaxial instrument, so as to realize the shear test by directly applying the axial force of the test through the upper soil pressure rod, and the hydraulic source of the triaxial testing equipment can also be directly connected to the airbag to realize the direct application of radial pressure to the soil sample through the airbag. The sampling device is directly applied to the triaxial instrument, which facilitates the test while avoiding changes in the stress state of the soil sample caused by moving the soil sample, thereby affecting the reliability of the measurement data.

[0095] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

[0096] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A soil sampling device capable of maintaining the initial stress state of a sample, characterized in that: include: An axial force measuring assembly (1), an axial pressure maintaining assembly (2), a radial pressure maintaining assembly (3), a sampling assembly (4), and a supporting base assembly (5); The axial force measuring assembly (1), the axial pressure maintaining assembly (2), the sampling assembly (4) and the supporting base assembly (5) are installed in sequence along the axial direction; The force measuring rod (101) of the axial force measuring assembly (1) and the upper soil pressing rod (202) of the axial pressure maintaining assembly (2) are axially arranged and contact-connected, and the upper soil pressing rod (202) is radially pressed and connected with a clamping bolt (203); The airbag (301) of the radial pressure-maintaining component (3) is installed in a radially encircling shape inside the soil sampling knife (401) of the sampling component (4), and the airbag (301) is externally connected to a fluid pressure source component; The support base assembly (5) is docked and mounted on the bottom of the soil cutting knife (401); The axial force measuring assembly (1) further comprises: a force measuring rod support seat (102) and a force measuring meter (103); The force measuring rod (101) is vertically movably connected to the force measuring rod support seat (102) via a thread; The force gauge (103) is mounted on the force measuring rod (101); The axial pressure-maintaining assembly (2) further comprises: an upper pressure rod support seat (201); The upper pressure rod support seat (201) is threadedly fixedly connected to the bottom of the force measuring rod support seat (102) of the axial force measuring assembly (1); The upper soil pressure rod (202) is vertically slidably connected to the upper soil pressure rod support seat (201), the top of the upper soil pressure rod (202) corresponds to the bottom of the force measuring rod (101), and a scale line is provided on the outer side of the upper soil pressure rod (202); The clamping bolt (203) is vertically connected to the side wall of the upper pressure rod support seat (201) through a thread, and the end of the clamping bolt (203) is in contact with and connected to the upper soil pressure rod (202) in the pressure regulating chamber.

2. The soil sampling device capable of maintaining the initial stress state of the sample as claimed in claim 1, characterized in that: The fluid pressure source assembly comprises: a pipeline switch (303), a pressure storage tank (304) and a pressure-maintaining air pump (305); The connection port of the airbag (301) is connected to the lower connection port of the pressure storage tank (304) via a pipeline, and the pipeline switch (303) is installed on the connection pipeline between the pressure storage tank (304) and the airbag (301); The pressure medium in the pressure storage tank (304) is water; The upper connection port of the pressure storage tank (304) is connected to an external pressure-maintaining air pump (305) via a pipeline.

3. The soil sampling device capable of maintaining the initial stress state of the sample as claimed in claim 1 or 2, characterized in that: The radial pressure-maintaining assembly (3) further comprises: an airbag support sleeve (302); The airbag support sleeve (302) is sleeved on the inner side of the airbag (301), and the airbag support sleeve (302) moves upward synchronously with the upper soil pressing rod (202).

4. The soil sampling device capable of maintaining the initial stress state of the sample as claimed in claim 1, characterized in that: The bottom blade of the soil taking knife (401) is conical, and an axial soil taking channel is provided through the center of the soil taking knife (401). The inner diameter of the soil taking channel is equivalent to the outer diameter of the soil sample to be taken, and an annular cylindrical airbag installation groove is provided on the inner side wall of the middle section of the soil taking channel of the soil taking knife (401).

5. The soil sampling device capable of maintaining the initial stress state of the sample as claimed in claim 1 or 4, characterized in that: The sampling assembly (4) further comprises: a soil cutting knife (402); A soil cutting slot is horizontally opened on the side wall of the lower end of the soil cutting knife (401), and the sheet-shaped soil cutting knife (402) is inserted into the soil cutting slot.

6. The soil sampling device capable of maintaining the initial stress state of the sample as claimed in claim 5, characterized in that: The support base assembly (5) comprises: a downward pressure soil rod (501) and a downward pressure rod base (502); The lower pressure rod base (502) is threadedly connected to the bottom of the soil cutting knife (401); The lower soil pressing rod (501) is vertically movably connected to the lower soil pressing rod base (502) via a thread, and a support seat is provided at the bottom of the lower soil pressing rod (501). As the lower soil pressing rod (501) moves upward relative to the lower soil pressing rod base (502), the bottom of the lower soil pressing rod base (502) is supported on the support seat at the bottom of the lower soil pressing rod (501).

7. The sampling method of the soil sampling device capable of maintaining the initial stress state of the sample as claimed in claim 6, characterized in that: Step 1: Dig a well or trench at the sampling site to the required depth for sampling and level the bottom; Step 2: Open and adjust the fluid pressure source assembly so that the pressure in the airbag (301) reaches a preset confining pressure; Step 3: Adjust the length of the clamping bolt (203) screwed into the upper pressure rod support seat (201), control the clamping bolt (203) to act on the upper pressure rod (202), and adjust the resistance of the upper pressure rod (202) to axial movement. At the same time, adjust the axial force measuring assembly (1) so that the reverse axial force applied by the upper pressure rod (202) to the axial force measuring assembly (1) reaches a preset axial pressure, and keep the clamping bolt (203) relatively fixed; Step 4: Remove the axial force measuring assembly (1) from the device, and extend the soil sampling knife (401) into the soil perpendicular to the sampling ground; Step 5: As the bottom blade of the soil taking knife (401) is pressed into the soil, the columnar soil sample enters the soil taking channel inside the soil taking knife (401) through the blade and pushes the upper soil pressing rod (202) upward. After the soil sample successfully enters the air bag (301), the soil taking knife (401) stops moving; Step 6: Cutting off the soil sample in the soil cutting knife (401) by using the soil cutting knife (402); Step 7: After the soil cutting knife (401) is taken out from the soil, the lower pressure rod base (502) of the supporting base assembly (5) is docked and installed on the bottom of the soil cutting knife (401), and the lower pressure rod (501) which is threadedly connected to the lower pressure rod base (502) is pressed against the bottom of the soil sample; Step 8: Control the lower soil pressing rod (501) to move upward until the bottom of the lower soil pressing rod base (502) is supported on the support seat at the bottom of the lower soil pressing rod (501).

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