CN105928803A - Soil shear strength parameter in-situ test apparatus and test method thereof - Google Patents

Abstract

The invention discloses an in-situ test device and a test method for shear strength parameters of soil. The in-situ testing device for the shear strength parameter of the soil comprises a drill pipe, a rotary drive device for driving the drill pipe to rotate, and a shearing instrument installed at the bottom of the drilling pipe; a pressure gauge is mounted on the outer wall of the shearing instrument , the pressure gauge is used to detect the normal stress generated by the in-situ soil on the shearer when the shearer rotates; driven by the rotary drive device, the shearer located below the surface of the in-situ soil and the pressure of the in-situ soil Shear failure occurred at the contact surface. The invention can directly measure the relevant parameters of the in-situ soil body, and has strong reliability, easy implementation, convenient use, good effect, low cost and wide application range.

Description

An in-situ test device and test method for shear strength parameters of soil

technical field

The invention relates to an in-situ testing device and a testing method for shear strength parameters of soil, belonging to the field of testing shear strength parameters of soil.

Background technique

The failure of most soils is shear failure, and the shear failure is basically subject to the Mohr-Coulomb (referred to as M-C) criterion. For example, if the slope is unstable and slides, it is manifested that the sliding force of the slope sliding body is greater than that of the slope The shear failure caused by the maximum anti-sliding force that can be exerted by the sliding surface can be obtained by the M-C criterion according to the actual sliding situation.

In the M-C criterion, there are two shear strength parameters, cohesion and internal friction angle. The magnitude of these two parameters represents the shear resistance (ie, shear strength) of the soil and reflects the shear failure of the soil structure. Therefore, the acquisition of shear strength parameters is the basic condition for analyzing soil shear failure, and provides a basis for accurately preventing soil shear failure and predicting the range of soil shear failure.

In order to obtain the M-C shear strength parameters of the soil, the original soil samples are usually collected from the actual engineering site, and then the collected original soil samples are reshaped in the room, and the multi-layered soil samples that can be used for direct shear or triaxial shear experiments are prepared. A group of standard soil samples, after changing the compression state of the soil samples, the shear strength of the soil under different normal stress states is obtained experimentally, and then these experimental results are used in the Cartesian coordinate system of normal stress and shear strength using M-C The intensity curve is fitted to obtain the M-C intensity parameters.

However, in the process of preparing the remodeled standard soil sample, the original state of the soil sample was disturbed, resulting in some differences in the stress state, water content and soil structure of the original soil sample and the remodeled standard soil sample. , so the M-C shear strength parameters of the remolded standard soil sample obtained from laboratory experiments cannot truly reflect the shear strength characteristics of the original soil sample. At the same time, because this method needs to prepare standard soil samples, the experimental operation process is relatively cumbersome, and the operating proficiency of the preparation personnel also has a certain impact on the performance of the prepared soil samples. In addition, for the soil stability controlled by shear failure, such as the sliding stability of slopes, the main factor affecting the analysis results is often the accuracy of the selection of shear strength parameters. If the shear strength parameters are compared with the actual engineering conditions When they do not match, the calculated results may be exaggerated or conservatively estimated, which will bring unfavorable hidden dangers to the project or cause uneconomical engineering optimization design.

In this case, there is an urgent need for an in-situ testing device and testing method that is easy to implement and can accurately obtain soil shear strength parameters.

Contents of the invention

The present invention aims to provide an in-situ testing device and testing method for shear strength parameters of soil. In the process of measuring soil shear strength parameters by the in-situ testing device, the operation is simple, data acquisition is fast, and accuracy is high. Labor cost is small.

In order to achieve the above object, the technical solution adopted in the present invention is:

An in-situ testing device for shear strength parameters of a soil body is characterized in that it includes a drill pipe, a rotary drive device for driving the drill pipe to rotate, and a shearing instrument installed at the bottom end of the drilling pipe; the shearing instrument A pressure gauge is installed on the outer wall of the machine, which is used to detect the normal stress generated by the in-situ soil on the shearer when the shearer rotates; driven by the rotary drive device, the shearer located below the surface of the in-situ soil Shear failure occurs at the interface with the in-situ soil.

As a result, the drill pipe is driven by the rotary drive device to rotate perpendicular to the ground, so that shear failure occurs between the shear instrument and the in-situ soil, so as to obtain the shear strength parameters of the soil.

According to the embodiments of the present invention, the present invention can also be further optimized, and the following is the technical scheme formed after optimization:

Preferably, the shearer is a cone shearer.

Preferably, the pressure gauge is a ring pressure gauge.

Preferably, the rotary drive device is a motor installed on the bracket, the power output end of the electrode is connected with the drill rod, the motor casing of the motor is equipped with a boom, and the lower end of the boom is fixed with a A casing outside the pole; preferably, the casing is formed by fixed connection of multiple detachable sections.

A gap is provided between the bottom end of the casing and the top end of the shearing instrument.

A sleeve is installed on the bracket, and the motor is fixed in the sleeve through a plurality of connecting rods.

The support includes a tripod and a support column on the surface of the in-situ soil, and a support beam fixed on the tripod and the support column and placed horizontally.

The drill pipe is fixedly connected by multiple detachable sections, and is used to collect normal stress and shear strength of in-situ soil at different depths.

Based on the same inventive concept, the present invention also provides a method for testing the in-situ soil using the shear strength parameter in-situ testing device of the soil, which includes the following steps:

S1, select a representative test point, set up a support at the test point, and install the in-situ test device for the shear strength parameter of the soil;

S2. The motor drives the drill pipe to rotate at a constant speed, so that the shearer drills into the in-situ soil at a specified depth;

S3. Obtain in-situ test data; when the drilled shear instrument reaches the specified depth below the in-situ soil surface, stop the rotation of the drill pipe and stop drilling. At this time, test the pressure gauge installed on the shear instrument. When the value displayed by the pressure gauge is stable, record the earth pressure exerted by the in-situ soil around the shear instrument on the shear instrument, that is, the normal stress of the in-situ soil at this depth; Adjust the input motor voltage to the maximum until the shearer forms a relative shear displacement to the in-situ soil around it, that is, the shearer destroys the in-situ soil around it, and the rate of shear displacement satisfies When required by the "Standards for Geotechnical Test Methods" (GB/T 50123-1999), record the voltage input to the motor at this time;

S4. Organize the data; input the voltage of the motor and the normal stress of the in-situ soil measured by the corresponding pressure gauge and the normal stress of the shear instrument when the shear instrument performs shear damage to the surrounding in-situ soil at different specified depths. Calculate the in-situ soil shear strength at different depths with shape parameters; then, plot the normal stress and corresponding shear strength data of this series of in-situ soil at different depths on the Cartesian coordinates of normal stress and shear strength In the system, the M-C strength curve was used to fit the test results to obtain the shear strength parameters of the in-situ soil.

Preferably, in step S4, the MC criterion formula is σ = c + τ tan φ , where σ is the in-situ soil normal stress, τ is the in-situ soil shear strength under the corresponding normal stress, and c is the The in-situ soil cohesion is corrected according to the indoor shear test data between the shear instrument and the soil and the soil, and φ is corrected according to the indoor shear test data between the shear instrument and the soil and the soil The internal friction angle of the in-situ soil, and c and φ are the shear strength parameters of the in-situ soil that need to be obtained by curve fitting, so as to obtain the shear strength parameters of the in-situ soil.

Therefore, when the motor drives the drill pipe to rotate to obtain in-situ test data, whenever the drilled shear instrument reaches the specified depth below the surface, the motor is turned off and the drilling is stopped. At this time, the test device installed on the shear instrument Pressure gauge, when the value displayed by the pressure gauge is stable, record the earth pressure exerted by the surrounding in-situ soil on the shearer; then, power on the motor again, and fine-tune the voltage input to the motor until the shearer When the in-situ soil forms relative shear displacement, and the rate of shear displacement meets the requirements stipulated in the "Standards for Geotechnical Test Methods", record the voltage input to the motor at this time; After the completion, disassemble the in-situ test device for the shear strength parameters of the soil; when sorting out the data, according to the design index of the motor, the shear instrument will be used to shear the in-situ soil around it at different specified depths. The voltage input to the motor at the time of destruction is converted into the rotational torque of the motor, that is, the maximum shearing torque when the shearing instrument shears and destroys the in-situ soil around it, and then measured by the converted rotational torque of the motor and the corresponding pressure The shear strength of the in-situ soil at different depths is calculated by the normal stress of the soil and the shape parameters of the shear instrument; then, the normal stress of the in-situ soil at different depths and the corresponding shear strength data of this series It is plotted in the Cartesian coordinate system of normal stress and shear strength, and the M-C strength curve is used to fit the test results, so as to obtain the shear strength parameters of the in-situ soil.

With the above structure, the in-situ test device of the soil shear strength parameter is composed of a cone shear instrument, a drill pipe, a motor and a connecting rod and a boom fixedly connected to its casing, a casing, a sleeve, a triangular It consists of brackets, support beams and support columns. Firstly, the test device is erected by using triangular brackets, support beams and support columns to form a support structure. Then, the sleeve is placed flat on the support beam and connected with the support beam. The rod embeds the motor in the inner wall of the sleeve. For the drill pipe, one end goes deep into the motor and connects with the motor rotor, and the other end is fixedly connected with the cone shear instrument. For the casing around the drill pipe, its bolts are connected to the suspender of the motor casing. After the test device is installed, when the motor is energized and rotated, its rotational torque can be converted into the shearing torque of the conical shearing instrument on the in-situ soil around it, and the instrument will be drilled into the soil as a whole and reach the specified depth. This obtains the normal stress of the soil at the corresponding depth and the shear strength of the soil under this normal stress. The test device can quickly and easily obtain test results, and can truly reflect the shear strength characteristics of the in-situ soil.

Compared with the prior art, the beneficial effects of the present invention are: the in-situ test device for soil shear strength parameters of the present invention can directly measure the relevant parameters of the in-situ soil, which is reliable, easy to implement, convenient to use, and effective Good quality, low cost and wide application range.

Description of drawings

Fig. 1 is a structural principle diagram of an embodiment of the present invention;

Fig. 2 is the schematic diagram of cone shear instrument of the present invention;

Fig. 3 is a schematic diagram of a cross-section of a motor according to the present invention;

Fig. 4 is a schematic cross-sectional view of the connection between the top sleeve and the boom according to the present invention;

Fig. 5 is a schematic diagram of the elevation of the connection between the top sleeve and the boom according to the present invention;

Fig. 6 is a schematic diagram of a connection cross-section of an intermediate sleeve segment according to the present invention;

Fig. 7 is a schematic elevation view of the connection of the intermediate sleeve segments according to the present invention.

In the picture:

1. Soil body; 2. Shearing instrument; 3. Pressure gauge; 4. Drill pipe; 5. Casing; 6. Motor; 7. Suspender; 8. Connecting rod; 9. Sleeve; 10. Bolt; 11 1. Support beam; 12. Support column; 13. Triangular bracket.

detailed description

The present invention will be described in detail below with reference to the accompanying drawings and examples. It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. For the convenience of description, if the words "up", "down", "left" and "right" appear in the following, it only means that the directions of up, down, left and right are consistent with the drawings themselves, and do not limit the structure.

An in-situ test device for soil shear strength parameters, as shown in Figure 1-7, mainly consists of a conical shear instrument, a drill pipe, a motor, a connecting rod and a suspender fixedly connected to its shell, a casing, It consists of a sleeve, a triangular bracket, a supporting beam and a supporting column. Firstly, the test device is erected by using triangular brackets, support beams and support columns to form a support structure. Then, the sleeve is placed flat on the support beam and connected with the support beam. The rod embeds the motor in the inner wall of the sleeve. For the drill pipe, one end goes deep into the motor and connects with the motor rotor, and the other end is fixedly connected with the cone shear instrument. For the casing around the drill pipe, its bolts are connected to the suspender of the motor casing. After the test device is installed, when the motor is energized and rotated, its rotational torque can be converted into the shearing torque of the conical shearing instrument on the in-situ soil around it, and the instrument will be drilled into the soil as a whole and reach the specified depth. This obtains the normal stress of the soil at the corresponding depth and the shear strength of the soil under this normal stress. The test device can obtain test results quickly and easily, and can truly reflect the shear strength characteristics of the in-situ soil.

The conical shearer of the present invention is a conical body with a height h ( h = 10cm) and a maximum radius r ( r = 5cm). When it works deep into the soil, only its sides form mutual shearing action with the soil. In addition, an annular pressure gauge is installed in the middle of the cone shearing instrument to obtain the average earth pressure (i.e., the normal stress of the soil) that the soil acts on the cone shearing instrument. In order to use the cone shear instrument to obtain the basic data of the shear strength parameters, at a specified depth below the surface, the normal stress of the soil at the depth is recorded by the ring pressure gauge, and the motor is rotated just to make the cone shear instrument The in-situ soil forms a relative shear displacement, even if the contact surface between the soil at the specified depth and the cone shear instrument undergoes shear failure, the motor torque at this time is the specified value of the cone shear instrument. The maximum shear moment required for shear failure of the soil at depth. Thus, according to the rotational torque of the motor, the normal stress of the soil at the specified depth and the shape characteristics of the cone shear instrument, the shear strength of the soil corresponding to the shear failure of the soil is calculated.

The motor shell of the present invention is designed with a suspender and a connecting rod that can be fixedly connected to the motor, wherein the motor can be embedded in the inner wall of the sleeve through the connecting rod, and the sleeve and the supporting structure connected to the sleeve are responsible for the rotation of the motor. The lateral force generated at the time ensures the smooth operation of the motor. At the same time, there is a triangular slot on the motor rotor, which facilitates the drill pipe at the top to go deep into the motor and connect with the motor rotor, so that the rotation of the motor is converted into the rotation of the cone shear instrument fixedly connected to the other end of the drill pipe. In addition, the voltage input to the motor can be adjusted, and the rotational torque of the motor can be controlled by the magnitude of the input voltage, so as to obtain the required torque for the conical shearer to shear and destroy the surrounding in-situ soil at a specified depth. The purpose of the maximum shearing torque.

The drill pipe of the present invention is a common drill pipe and can be used in common with exploration drill pipes. At the same time, the drill rod at the bottom end is fixedly connected to the cone shearing instrument, the drill rod at the top goes deep into the motor, and is connected to the motor rotor in a triangular embedding manner. The middle drill rod is composed of multiple segments to meet different drilling depths, and each segment The rods are connected by a male and female threaded connection.

The casing of the present invention is combined with two semi-cylindrical shells through a nested bolt connection, so as to facilitate modular production and facilitate installation on the outer periphery of the drill pipe. At the same time, there is a certain gap between the bottom casing and the cone shearing instrument to ensure that the casing does not affect the use of the cone shearing instrument when the cone shearing instrument is working. The top casing is connected to the motor casing by bolts. Connected with the boom on the top, so that the casing and the drill pipe connected to the motor can be drilled into the soil at the same speed, and the purpose of protecting the surrounding soil wall of the borehole to prevent the hole from collapsing is completed. The intermediate casing is composed of multiple sections to meet different drilling depths. The length of each section of casing can be the same as that of each section of drill pipe, and each section of casing is connected by nested bolt connection.

The present invention will be described in detail below with a specific engineering example.

As shown in Figures 1-7, the project is an accumulation slope with a height of 96m and an average slope angle of 15°. Among them, the natural weight of the accumulation is 18.2kN/m³ and the saturated weight is 21.6kN/m³. During the slope construction process, due to the influence of rainfall and artificial disturbance, the slope of the accumulation body has shown a sliding tendency. Therefore, in order to ensure that the slope can maintain stability during subsequent construction and operation, it is necessary to correctly evaluate the stability of the slope on the basis of However, the key factor for carrying out this work is whether the real and reliable slope resistance parameters can be obtained. Therefore, this project selects representative test points on site to carry out the anti-slide resistance of accumulated soil. In situ testing of shear strength parameters. Before starting the in-situ test, level the selected representative test points and install the in-situ test device. After the device is installed, the motor is powered on, and the drill pipe is pushed into the cone shearer to drill into the soil to a certain depth. At the same time, during the drilling process, the input motor voltage is stably controlled to keep the drill pipe drilled into the soil at a constant speed. Afterwards, when the cone shear instrument drilled into the soil at a depth of 20cm, the motor was turned off, the drilling was stopped, and the annular pressure gauge installed on the cone shear instrument was tested, and the in-situ soil around the cone at this time was recorded. The earth pressure (i.e. the normal stress of the soil at this depth) acted by the shear instrument. Then, power on the motor again, and fine-tune the voltage input to the motor until the conical shearing instrument forms a relative shear displacement to the in-situ soil around it, record the voltage input to the motor at this time, and input the voltage according to the design index of the motor The voltage is converted into the rotation torque of the motor, and then the rotation torque of the motor (that is, the maximum shear torque when the cone shear instrument shears and destroys the surrounding in-situ soil) and the normal stress of the soil and the cone shear Calculate the shear strength of the soil at this depth by using the shape parameters of the instrument. According to the above process, the normal stress and shear strength data of the soil at a total of 5 points at depths of 20cm, 40cm, 60cm, 80cm and 100cm below the surface were obtained. The data of these 5 points are plotted in the Cartesian coordinate system of normal stress and shear strength, and the M-C strength curve is used for fitting, so as to obtain the result of the slope's anti-sliding strength parameter, and the slope is reinforced according to the result and analyze its stability.

The specific operation is as follows:

(1) Select representative test points. According to the scope, nature and characteristics involved in the project, select representative test points to obtain the in-situ data of the shear strength of soil 1. Safety protection measures shall be formulated according to the provisions of Engineering Survey Safety Code (GB 50585-2010).

(2) Erection of supporting structures. On the leveled ground, with the test point as the center, 4 triangular brackets 13, 4 support beams 11 and 4 support columns 12 are evenly and symmetrically arranged in each direction of the plane as the support structure of the in-situ test device, wherein , the triangular bracket 13 is located on the outside of the support beam 11, and the support column 12 is located on the inside of the support beam 11. At the same time, the triangular bracket 13 and the support column 12 go deep into the soil 1 to a certain depth, and ensure that the support beam 11 can be stable and reliable. And place it horizontally on the triangular support 13 and the supporting beam 12.

(3) Install the in-situ test device. After erecting the support structure, place the sleeve 9 stably on the support beam 11 and connect it with the support beam 11, and ensure that the center of the sleeve 9 and the test point are at the same position in the vertical direction. Then, the motor 6 is nested on the inner wall of the sleeve 9 by the connecting rod 8 fixedly connected with the motor 6 shell, and the drill rod 4 connected with the cone shear instrument 2 at the bottom is installed in place, and the drill rod 4 The top goes deep into the inside of the motor 6 and is connected to the rotor of the motor 6 in an embedded manner. Finally, a casing 5 is installed on the periphery of the drill pipe 4, wherein the top of the casing 5 is connected to the suspender 7 on the casing of the motor 6 by means of bolts 10, and the bottom of the casing 5 is connected to the top of the cone shear instrument 2. There is a certain gap on the surface.

(4) Drill into the cone shear instrument. After the in-situ test device is installed, power on the motor 6, drill into the cone shear instrument 2 at a specified depth, and stably control the voltage input to the motor 6 during the drilling process to ensure that the drill pipe 4 drills into the soil 1 at a uniform speed, At the same time, in order to meet the requirements of different drilling depths, drill pipe 4 and casing 5 sections can be continuously inserted therein.

(5) Obtain in-situ test data. Whenever the cone shear instrument 2 drilled reaches the specified depth below the surface, the motor 6 is turned off and the drilling is stopped. At this time, the annular pressure gauge 3 installed on the cone shear instrument 2 is tested, wherein the annular pressure The measuring range and accuracy requirements of gauge 3 meet the requirements of "Standards for Geotechnical Test Methods" (GB/T 50123-1999). When the value displayed by annular pressure gauge 3 is stable, record the surrounding in-situ soil 1 pair of cone shears. The earth pressure acted by instrument 2 (that is, the normal stress of the soil at this depth). Then, turn on the motor 6 again, and fine-tune the voltage input to the motor 6 until the cone shearing instrument 2 forms a relative shear displacement to the in-situ soil 1 around it (that is, at this time, the cone shearing instrument 2 forms a relative shear displacement to the surrounding original soil 1). When the bit soil has undergone shear failure), and the rate of shear displacement meets the requirements stipulated in the "Standards for Soil Test Methods" (GB/T 50123-1999), record the voltage input to the motor 6 at this time.

(6) Disassemble the in-situ test device and supporting structure. Input when all the in-situ test data of soil 1 at the specified depth (including the normal stress of soil 1 at the specified depth and the shear failure of the in-situ soil 1 around it by the cone shear instrument 2 at the specified depth After the voltage of the motor 6) is obtained, disassemble the in-situ test device and the supporting structure according to the reverse order of the installation, clean up each component, and pack it into a box for storage.

(7) Organize data. According to the design index of the motor 6, the voltage input to the motor 6 is converted into the rotational torque of the motor 6 when the conical shear instrument 2 shears and destroys the in-situ soil 1 around it at different specified depths (that is, the conical shear The maximum shearing moment when shearing instrument 2 shears and destroys the in-situ soil 1 around it), and then the converted rotational torque of motor 6 and the soil normal stress and cone shape measured by the corresponding ring pressure gauge 3 The shape parameters of the shear instrument 2 are used to obtain the shear strength of the soil body 1 at different depths. Then, the normal stress and the corresponding shear strength data of soil 1 at different depths of this series are plotted in the Cartesian coordinate system of normal stress and shear strength, and the test results are fitted by the MC strength curve, where, The MC criterion formula is σ = c + τ tan φ , where σ is the normal stress of the soil, τ is the shear strength of the soil under the corresponding normal stress, and c is the indoor shear strength between the shear instrument and the soil and the soil. The cohesion of the soil is corrected by cutting the experimental data, φ is the internal friction angle of the soil which is corrected according to the indoor shear test data between the shear instrument and the soil and the soil, and c and φ are the curves to be fitted Combine the obtained soil shear strength parameters, so as to obtain the shear strength parameters of soil 1. In the process of data collation, the requirements for data processing and chart drawing in the "Standards for Soil Test Methods" (GB/T 50123-1999) should be met.

The above-mentioned embodiments should be understood that these embodiments are only used to illustrate the present invention more clearly, and are not intended to limit the scope of the present invention. After reading the present invention, those skilled in the art will understand the various equivalent forms of the present invention All modifications fall within the scope defined by the appended claims of this application.

Claims (10)

1. An in-situ test device for shear strength parameters of soil, characterized in that it includes a drill pipe (4), a rotary drive device for driving the drill pipe (4) to rotate, and a device installed at the bottom of the drill pipe (4). The shearing instrument (2) at the end; the outer wall of the shearing instrument (2) is equipped with a pressure gauge (3), which is used to detect the impact of the in-situ soil on the shearing instrument (2) when the shearing instrument (2) rotates. 2) The normal stress generated; driven by the rotary drive device, the contact surface between the shear instrument (2) located below the in-situ soil surface and the in-situ soil undergoes shear failure. 2 . The in-situ testing device for shear strength parameters of soil according to claim 1 , wherein the shearing instrument ( 2 ) is a cone shearing instrument. 3 . 3 . The in-situ test device for shear strength parameters of soil according to claim 1 , wherein the pressure gauge ( 3 ) is a ring pressure gauge. 4 . 4. The in-situ test device for shear strength parameters of soil according to any one of claims 1-3, characterized in that, the rotary drive device is a motor (6) mounted on a bracket, and the electrode (6) The power output end of the motor (6) is connected with the drill pipe (4), the motor housing of the motor (6) is equipped with a suspender (7), and the lower end of the suspender (7) is fixed with a Casing (5); preferably, the casing (5) is fixedly connected by multiple detachable sections. 5. The in-situ testing device for shear strength parameters of soil according to claim 4, characterized in that, there is a gap. 6. The in-situ testing device for shear strength parameters of soil according to claim 4, characterized in that a sleeve (9) is mounted on the support, and the motor (6) passes through a plurality of connecting rods (8) fixed in the sleeve (9). 7. The in-situ testing device for shear strength parameters of the soil according to any one of claims 4-6, characterized in that the support includes a tripod (13) on the surface of the in-situ soil (1) and Support column (12), be fixed on the support beam (11) that horizontally places on tripod (13) and support column (12). 8. The in-situ testing device for shear strength parameters of soil according to any one of claims 1-6, characterized in that, the drill pipe (4) is made of multiple detachable fixed connections for collecting different Normal stress and shear strength of soil in situ at depth. 9. A method for testing the in-situ soil by the shear strength parameter in-situ testing device of the soil according to any one of claims 1-8, characterized in that, comprising the steps of: S1, select a representative test point, set up a support at the test point, and install the shear strength parameter in-situ testing device of the soil as claimed in one of claims 1-8; S2. The motor (6) drives the drill pipe to rotate at a constant speed, so that the shearer (2) drills into the in-situ soil at a specified depth; S3. Obtain in-situ test data; when the drilled shear instrument (2) reaches the specified depth below the in-situ soil surface, stop the rotation of the drill pipe and stop drilling. At this time, the test is installed on the shear instrument (2) ) on the pressure gauge (3), when the value displayed by the pressure gauge (3) is stable, record the earth pressure exerted by the in-situ soil (1) around the shear gauge (2) on the shear gauge (2) , that is, the normal stress of the in-situ soil at this depth; then, turn on the motor, control and adjust the input motor voltage from small to large, until the shearer (2) forms a relative shear to the in-situ soil (1) around it Displacement, that is, when the shear instrument (2) shears and destroys the in-situ soil (1) around it, and the rate of shear displacement meets the requirements specified in the "Standards for Soil Test Methods", record the input motor at this time ( 6) the voltage; S4. Organize the data; when the shear instrument (2) is used to shear and destroy the in-situ soil (1) around it at different specified depths, the voltage input to the motor (6) and the corresponding pressure gauge (3) are measured The normal stress of the in-situ soil and the shape parameters of the shear instrument (2) are used to obtain the shear strength of the in-situ soil (1) at different depths; then, the series of in-situ soils (1) at different depths The normal stress and corresponding shear strength data are plotted in the Cartesian coordinate system of normal stress and shear strength, and the M-C strength curve is used to fit the test results to obtain the shear strength parameters of the in-situ soil (1) . 10. The method for testing the in-situ soil according to claim 9, characterized in that, in step S4, the MC criterion formula is σ = c + τ tan φ , where σ is the normal stress of the in-situ soil , τ is the in-situ soil shear strength under the corresponding normal stress, c is the in-situ soil cohesion corrected according to the indoor shear experiment data between the shear instrument and the soil and the soil, and φ is the cohesion of the soil according to The internal friction angle of the in-situ soil is corrected by the indoor shearing experiment data between the shear instrument and the soil and the soil, and c and φ are the in-situ soil shear strength parameters obtained by curve fitting, so that Obtain the shear strength parameters of the in-situ soil mass.