High-pressure seepage effect under weathered granite soil body shearing strength test device and method

Abstract

This application relates to a testing device and method for the shear strength of weathered granite soil under high-pressure seepage. This application is applicable to the field of geotechnical testing technology. The main structure of the testing device for the shear strength of weathered granite soil under high-pressure seepage is as follows: Inside the test chamber, from bottom to top, are arranged a lower water collection and diversion component, a soil sample installation area, and an upper water collection and equalization component. All three are completely covered by a flexible impermeable membrane, forming a sample assembly. A high-pressure seepage control mechanism is connected to the upper water collection and equalization component to apply a constant high-pressure seepage water pressure to the test soil sample; a controllable drainage and liquid collection mechanism is located at the bottom of the chamber and connected to the lower water collection and diversion component to discharge seepage water; an axial consolidation loading mechanism is located above the chamber to apply a constant axial consolidation pressure; the shear execution end of the in-situ shearing mechanism is pre-embedded in the test soil sample to perform in-situ shearing; a data acquisition instrument is connected to corresponding sensors to synchronously collect shear torque, shear stress, and pore water pressure.

Description

Technical Field

[0001] This invention relates to a testing device and method for the shear strength of weathered granite soil under high-pressure seepage. It is applicable to the field of geotechnical testing technology. Background Technology

[0002] Weathered granite soil is a soil body composed of coarse-grained rock fragments and fine clay minerals formed by the intense physical and chemical weathering of granite. It includes residual granite soil and completely weathered granite soil. Weathered granite soil is mostly sandy clay or clayey sand, and generally has distinct characteristics such as "intense weathering, high sand content, poor cementation, easy softening and disintegration upon contact with water, and poor erosion resistance".

[0003] In recent years, pumped-storage power stations have been vigorously developed for peak shaving and valley filling, alleviating power shortages and grid loads. The construction of these stations has created unique hydrogeological environments in reservoir areas. For example, weathered granite slopes in reservoir areas will be affected by frequent reservoir water level fluctuations caused by power station operation. The water level drawdown depth in pumped-storage reservoirs can reach 20-30 meters, generating dynamic water pressure of 200-300 kPa in the soil during this process. This periodic seepage erosion alters the microstructure and macroscopic mechanical properties of the weathered granite soil, deteriorating its shear strength and potentially affecting slope stability. Developing suitable experimental equipment to study the shear strength of weathered soil under high-pressure seepage is crucial for evaluating the stability of reservoir slope engineering.

[0004] To date, researchers have primarily conducted seepage erosion tests first, then remodeled the eroded soil samples, and finally studied the mechanical properties of the remodeled samples using traditional shear apparatus or triaxial apparatus. However, the soil remodeling process severely disturbs the microstructure of the soil samples, thereby affecting their strength characteristics and making it difficult for the test results to accurately reflect the mechanical characteristics of weathered granite soil after seepage erosion. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a device and method for testing the shear strength of weathered granite soil under high-pressure seepage, in view of the above-mentioned problems.

[0006] The technical solution adopted in this invention is: a test device for the shear strength of weathered granite soil under high-pressure seepage, comprising: The test chamber is arranged from bottom to top as follows: a lower water collection and diversion component, a soil sample installation area, and an upper water collection and equalization component. The sides of the lower water collection and diversion component, the soil sample installation area, and the upper water collection and equalization component are all covered with a flexible impermeable membrane to form a sample assembly. The high-pressure seepage control mechanism is connected to the water collection and equalization component in the upper part of the test chamber, and is used to apply a constant high-pressure seepage water pressure to the test soil sample in the soil sample installation area. A controllable drainage and liquid collection mechanism is located at the bottom of the test chamber and is connected to the lower water collection and diversion assembly for discharging seepage water. An axial consolidation loading mechanism is disposed above the test chamber and is used to apply a constant axial consolidation pressure to the sample assembly inside the test chamber. The in-situ shearing mechanism has its shearing actuator embedded inside the test soil sample in the soil sample installation area, and is used to perform in-situ shearing on the undisturbed soil sample. The data acquisition instrument is electrically connected to the stress sensor of the in-situ shearing mechanism and the pore pressure monitoring sensor in the test soil sample to simultaneously acquire shear torque, shear stress and pore water pressure.

[0007] By integrating consolidation, high-pressure seepage, in-situ shearing, and data acquisition into a single process, the entire test can be completed without remodeling the soil sample. The flexible impermeable membrane blocks lateral bypass leakage and limits the vertical seepage path to ensure accurate simulation of high-pressure seepage conditions. In-situ shearing preserves the original microstructure of the soil, and the simultaneous acquisition of multiple parameters ensures that the test data truly reflects the mechanical properties of the soil after seepage erosion, thus fundamentally solving the core problem of soil sample remodeling disturbance.

[0008] As a preferred embodiment, the test chamber includes a base and a transparent cylinder mounted on the base.

[0009] As a preferred embodiment, the lower water collection and diversion component includes a lower permeable stone and a lower water collection chamber located above the lower permeable stone, wherein the lower water collection chamber is a hollow pressure-bearing structure with uniformly distributed water distribution holes on its upper and lower surfaces.

[0010] Through the above-mentioned technical means, the permeable stone achieves uniform water permeability and diversion, and the lower water collection chamber can intercept fine particles generated by soil erosion and only allow water to pass through. This ensures that the seepage path is unobstructed and that erosion products can be retained for subsequent analysis, which is suitable for the easily eroded characteristics of weathered granite soil.

[0011] As a preferred embodiment, the upper water collection and equalization component includes an upper permeable stone and an upper water collection chamber located above the upper permeable stone, wherein the upper water collection chamber is a hollow pressure-bearing structure with uniformly distributed water holes on its lower surface.

[0012] Through the above-mentioned technical means, the upper water collection tank evenly distributes high-pressure water to the surface of the soil sample, and the upper permeable stone further homogenizes the water flow, so that the high-pressure seepage pressure acts evenly on the test soil sample throughout the entire area, accurately simulating the uniform seepage field of the reservoir area.

[0013] As a preferred embodiment, the high-pressure seepage control mechanism includes a high-pressure nitrogen tank and a constant-pressure water tank, wherein the high-pressure nitrogen tank is connected to the constant-pressure water tank to provide a constant pressure to the constant-pressure water tank, and the constant-pressure water tank is connected to the upper water collection and equalization component.

[0014] By employing the aforementioned technical means and using high-pressure nitrogen gas for stable water supply, high-pressure seepage pressure can be stably provided, accurately matching the dynamic water pressure conditions generated by the drop in water level in the pumped storage power station reservoir, thus solving the problem of the inability to constantly simulate high-pressure seepage.

[0015] As a preferred embodiment, the axial consolidation loading mechanism includes a rigid frame and a jack, with the upper end of the jack abutting against the rigid frame and the lower end abutting against the sample assembly via a pressure plate.

[0016] As a preferred embodiment, the in-situ shearing mechanism includes a motor, a torque sensor, a drill rod, a cross shear plate, and a casing. The cross shear plate is pre-embedded in the test soil sample as the shearing execution end, the casing is fitted onto the drill rod, and the top of the sample assembly is provided with a water-stop pad adapted to the casing.

[0017] Through the above technical means, the pre-embedded cross shear plate realizes in-situ shearing of the original soil without disturbance. The sleeve and the water stop pad work together to prevent high-pressure water from seeping up along the sleeve gap, ensuring stable seepage pressure and avoiding leakage from affecting the test results.

[0018] As a preferred embodiment, the in-situ shearing mechanism is equipped with a lifting component for adjusting the vertical position of the in-situ shearing mechanism.

[0019] The height of the in-situ shearing mechanism can be flexibly adjusted to adapt to shear tests of soil samples at different heights.

[0020] A test method for the shear strength of weathered granite soil under high-pressure seepage includes: S1. Close the controllable drainage and liquid collection mechanism, apply constant axial consolidation pressure to the soil sample through the axial consolidation loading mechanism, inject water into the upper water collection and equalization component to fully saturate the soil sample, and complete consolidation and saturation after the stress sensing data stabilizes. S2. Activate the controllable drainage and liquid collection mechanism, and apply a constant high-pressure seepage pressure to the soil sample through the high-pressure seepage control mechanism. Once the pore water pressure data is stable, establish a stable seepage erosion field. S3. Drive the in-situ shearing mechanism to rotate at a constant speed to perform undisturbed in-situ shearing on the undisturbed soil sample, and simultaneously collect shearing torque, shear surface normal stress and pore water pressure at the corresponding position. S4. Repeat the above test by changing the consolidation pressure and seepage pressure. Based on the effective stress principle and the calculation of multiple shear surface torque superposition, the shear strength parameters of the soil sample are obtained by linear fitting.

[0021] As a preferred embodiment, step S4 includes: Based on the three effective shear surfaces formed by the cross shear plate in the in-situ shearing mechanism—the circular top surface, the circular bottom surface, and the cylindrical side surface—the effective shear stress and corresponding torque of each shear surface are calculated, and then superimposed to obtain the peak total torque. The formula for total torque is rearranged as follows: The linear form is based on the peak total torque corresponding to each consolidation pressure. The independent variable A, determined by the normal pressure at each shear surface and the pore water pressure, is... T Linear fitting in the -A coordinate system yields the soil sample's internal friction angle φ and cohesion c.

[0022] The beneficial effects of this invention are: by using a high-pressure seepage control mechanism, a controllable drainage and liquid collection mechanism, and an axial consolidation loading mechanism to simulate the coupled working condition of 200~300kPa high-pressure seepage + consolidation pressure, this invention accurately restores the real hydrogeological environment of the water level drop in the reservoir area of ​​a pumped storage power station, avoids soil sample remodeling disturbance, and fills the technical gap in the test simulation of this type of high-pressure seepage coupled working condition.

[0023] This invention uses a flexible impermeable membrane to fully cover the specimen assembly, blocking lateral bypass leakage, limiting the vertical seepage path to a single path, ensuring stable high-pressure seepage, and ensuring that the test conditions are highly consistent with actual engineering conditions.

[0024] This invention employs in-situ shearing technology for undisturbed soil, with pre-embedded cross-shaped shearing plates. This eliminates the need to reshape the soil sample after seepage and erosion, thus completely solving the problems of soil sample reshaping disturbing the microstructure and the inability of test results to truly reflect the mechanical characteristics of weathered granite soil.

[0025] This invention integrates consolidation loading, high-pressure seepage, in-situ shearing, and data acquisition into one system, enabling continuous testing from "consolidation → saturation → high-pressure seepage erosion → shearing". This solves the shortcomings of existing technologies where seepage and shearing tests are performed in steps and the process is cumbersome, thus significantly improving testing efficiency.

[0026] This invention constructs a linear fitting formula based on the effective stress principle and the multi-shear surface torque superposition method, which can accurately calculate the soil cohesion and internal friction angle, providing reliable experimental data support for the stability evaluation of weathered granite slopes in reservoir areas. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the shear strength testing device in the embodiment.

[0028] Figure 2 This is a three-dimensional view of the test chamber in the embodiment.

[0029] Figure 3 This is a schematic diagram of the upper water collection tank in the embodiment.

[0030] Figure 4This is a schematic diagram of the lower water collection tank in the embodiment.

[0031] Figure 5 This is a three-dimensional view of the cross-shaped shear plate in the embodiment.

[0032] Figure 6 This is a schematic diagram of the effective shear surface formed by shearing in the embodiment.

[0033] Figure 7 The shear curve of the test soil sample under high-pressure seepage in the example is shown.

[0034] Figure 8 The shear strength fitting curve of the test soil sample under high-pressure seepage in the example is shown.

[0035] In the diagram: 1-Test chamber; 10-Test soil sample; 11-Base; 12-Transparent cylinder; 13-Lower permeable stone; 14-Lower water collection chamber; 15-Upper permeable stone; 16-Upper water collection chamber; 17-Flexible impermeable membrane; 18-Liquid tank; 111-Drainage pipe; 112-Drainage valve; 160-Water hole; 21-Frame base; 22-Frame column; 23-Pressure beam; 24-Jack; 25-Pressure plate; 26-Servo loading control system; 31-High-pressure nitrogen tank; 32-Constant pressure water tank; 33-Air inlet. 34-Outlet; 35-Air guide pipe; 36-Inlet pipe; 41-Frame column; 42-Lifting component; 43-Motor; 44-Torque sensor; 45-Connector; 46-Drill rod; 47-Cross shear plate; 48-Casing; 471-Top strain gauge; 472-Bottom strain gauge; 473-Side strain gauge; 5-Data acquisition instrument; 51-Top micro piezometer; 52-Bottom micro piezometer; 53-Side micro piezometer; 61-Circular top surface; 62-Circular bottom surface; 63-Cylindrical side surface. Detailed Implementation

[0036] This embodiment is a test device for the shear strength of weathered granite soil under high pressure seepage, including a test chamber, a high pressure seepage control mechanism, an axial consolidation loading mechanism, an in-situ shear mechanism, a controllable drainage and liquid collection mechanism, and a data acquisition instrument.

[0037] In this example, the test chamber includes a base and a transparent cylinder. The transparent cylinder is sealed and mounted on the base, with Vaseline applied to the joints for sealing. Inside the transparent cylinder, from bottom to top, are arranged a lower water collection and diversion assembly, a test soil sample, and an upper water collection and equalization assembly. In this embodiment, the lower water collection and diversion assembly includes a lower permeable stone and a lower water collection chamber located above the lower permeable stone. The lower water collection chamber is a hollow cylindrical steel plate with uniformly distributed water distribution holes of 1 mm diameter on its upper and lower surfaces. The upper water collection and equalization assembly includes an upper permeable stone and an upper water collection chamber located above the upper permeable stone. The upper water collection chamber is a hollow cylindrical steel plate with uniformly distributed water distribution holes of 1 mm diameter on its lower surface. In this embodiment, the sides of the lower permeable stone, lower water collection chamber, test soil sample, upper permeable stone, and upper water collection chamber are entirely covered with a flexible impermeable membrane (such as a transparent rubber membrane) to fill the gap between the soil sample and the transparent cylinder, blocking lateral leakage and limiting a single vertical seepage path.

[0038] In this example, the high-pressure seepage control mechanism includes a high-pressure nitrogen tank, a constant-pressure water tank, a gas guide steel pipe, a water inlet pipe, and a servo pressure control valve. The constant-pressure water tank has an air inlet and a water outlet. The air inlet is connected to the high-pressure nitrogen tank through the gas guide steel pipe. The servo pressure control valve is installed on the gas guide steel pipe. The water outlet is connected to the upper water collection tank through the water inlet pipe. The connection between the water inlet pipe and the upper water collection tank is sealed with Vaseline. This allows for precise control and a constant high-pressure seepage water pressure of 200~300kPa.

[0039] In this embodiment, the controllable drainage and liquid collection mechanism includes a drainage pipe, a drainage valve, and a liquid tank. One end of the drainage pipe is connected to the bottom of the inner cavity of the test chamber, and the other end is connected to the liquid tank via the drainage valve. It is used to discharge seepage water and collect fine particles of soil erosion.

[0040] In this embodiment, the axial consolidation loading mechanism includes a rigid frame, jacks, a pressure plate, and a servo loading control system. The rigid frame consists of a frame base, frame columns, and a pressure beam. The jacks are symmetrically arranged below the pressure beam, and the bottom of the jacks abuts against the upper water collection tank through the pressure plate. The servo loading control system controls the jacks to apply and maintain a constant axial consolidation pressure.

[0041] In this example, the in-situ shearing mechanism includes a lifting component, a motor, a torque sensor, a drill rod, a cross shear plate, a casing, and a water-stop pad. The lifting component is mounted on the pressure beam, and the motor is fixed to the lifting component, allowing for vertical adjustment. The cross shear plate is pre-embedded in the test soil sample as the shearing execution end. One end of the drill rod is fixed to the motor shaft via a connector, and the other end is fixed to the cross shear plate. The casing is fitted onto the outside of the drill rod. Through holes are opened in the center of the upper permeable stone, the upper water collection chamber, the pressure plate, and the pressure beam for the drill rod and casing to pass through. A water-stop pad is installed at the contact point between the casing and the upper water collection chamber to prevent high-pressure water from seeping upwards through the gap between them. In this embodiment, stress sensors, using strain gauges (top, bottom, and side strain gauges), are installed on the edges of the cross shear plate to monitor the normal stress on each shear surface.

[0042] During the shear test, the cross shear plate will form three effective shear surfaces in the test soil sample: a circular top surface, a circular bottom surface, and a cylindrical side surface. The circular top surface is the remaining part of the entire circle after deducting the cross section of the drill rod. Let the height of the cross shear plate be H and the radius be R1, and the radius of the drill rod be R2. Then, the area of ​​each effective shear surface can be calculated.

[0043] In this embodiment, three sets of pore pressure monitoring sensors were embedded inside the test soil sample. These were miniature piezometers: a top surface miniature piezometer at the same height as the strain gauge on the top surface of the cross shear plate, a bottom surface miniature piezometer at the same height as the strain gauge on the bottom surface of the cross shear plate, and a side surface miniature piezometer at the same height as the strain gauge on the side surface of the cross shear plate. These sensors were used to monitor the pore water pressure on each shear surface.

[0044] In this example, the data acquisition instrument is electrically connected to the torque sensor, strain gauge, and miniature piezometer to simultaneously acquire shear torque, shear surface normal stress, and pore water pressure.

[0045] This embodiment describes a method for testing the shear strength of weathered granite soil under high-pressure seepage, which specifically includes the following steps: S0. Secure and seal the transparent cylinder to the base, and place the lower permeable stone and the lower water collection chamber in sequence; fill the weathered granite undisturbed soil sample to the test height, pre-embed the cross shear plate and drill rod, and continue filling to the design height after putting on the sleeve; install the upper permeable stone, the upper water collection chamber, and the pressure plate in sequence, and fully cover the specimen assembly with a flexible impermeable membrane; place the test chamber in the center of the rigid frame to complete the device assembly.

[0046] S1. Close the drain valve of the controllable drainage and liquid collection mechanism, apply a constant axial consolidation pressure to the soil sample through the axial consolidation loading mechanism, with a consolidation pressure value of P1, and inject water into the upper water collection and equalization component to fully saturate the soil sample. After the stress sensing data stabilizes, the consolidation and saturation are completed.

[0047] S2. Open the drain valve of the controllable drainage and liquid collection mechanism, and apply a constant high-pressure seepage pressure to the soil sample through the high-pressure seepage control mechanism. The seepage pressure value is Q1. After the pore water pressure data stabilizes, a stable seepage erosion field is established.

[0048] S3. Drive the in-situ shearing mechanism to rotate at a constant speed to perform undisturbed in-situ shearing on the undisturbed soil sample, and simultaneously collect the shearing torque, normal stress on the shear surface, and pore water pressure at the corresponding position to obtain the shear curve of the rotational torque with respect to the rotation angle.

[0049] The motor is moved to a suitable position using the lifting component of the in-situ shearing mechanism. The motor shaft is fixed to the drill rod via a connector. The motor is then turned on, and the drill rod is rotated at a constant rate of 1° / 10s to 2° / 10s, which drives the cross shear plate to shear the test soil sample.

[0050] S4. Repeat the above test by changing the consolidation pressure and seepage pressure. Based on the effective stress principle and the calculation of multiple shear surface torque superposition, the shear strength parameters of the soil sample are obtained by linear fitting.

[0051] S41. Unload the test soil sample from the transparent cylinder, and then select different consolidation pressures P, such as P2, P3, ..., P n Repeat steps S0 to S3 to obtain shear curves under different consolidation pressure P values.

[0052] S42. When the shear plate rotates, it forms three effective shear surfaces: a circular top surface, a circular bottom surface, and a cylindrical side surface. Let the normal stresses measured by strain gauges on the three shear surfaces be σ1, σ2, and σ3, respectively, and the corresponding pore water pressures measured by micro-piezometers be u1, u2, and u3, respectively. Then, according to the effective stress principle, the shear stresses on the three shear surfaces are as follows: τ1=(σ1-u1)×tan φ + c (1) τ2=(σ2-u2)×tan φ + c (2) τ3=(σ3-u3)×tan φ + c (3) In the formula φ Let be the friction angle. c It represents cohesive force.

[0053] Based on the area of ​​each effective shear surface, the torque generated by the shear resistance on the three shear surfaces is calculated as follows: (4) (5) (6) Select the peak points of the shear curves corresponding to each consolidation pressure P value. T f ,but (7) By combining equations (1) to (7), we can obtain: (8) in, , is the independent variable; B = , is a constant.

[0054] Equation It can be regarded as a transformed Mohr-Coulomb strength criterion.

[0055] Based on the various consolidation pressures P1, P2, P3, ..., P n Below, the corresponding peak point of the shear curve T f 1. T f 2. T f 3、...、 T f n The normal pressure and pore water pressure on each shear surface are calculated according to equation (8). A 1. A 2. A 3、...、 A n Then T - A Plot the corresponding sets of experimental data in the coordinate system. A n , T f n By performing linear fitting on each set of data, the friction angle of the soil sample after seepage erosion can be obtained. φ and cohesion c The fitted curve is in T The intercept on the axis is B · c The fitted curve and A The included angle of the axis is φ .

[0056] S43. Select different osmotic pressures Q, such as Q2, Q3, ..., Q n By repeating the above steps, the shear curves and shear strength under different osmotic pressure Q values ​​can be obtained.

Claims

1. A test device for the shear strength of weathered granite soil under high-pressure seepage, characterized in that, include: The test chamber is arranged from bottom to top as follows: a lower water collection and diversion component, a soil sample installation area, and an upper water collection and equalization component. The sides of the lower water collection and diversion component, the soil sample installation area, and the upper water collection and equalization component are all covered with a flexible impermeable membrane to form a sample assembly. The high-pressure seepage control mechanism is connected to the water collection and equalization component in the upper part of the test chamber, and is used to apply a constant high-pressure seepage water pressure to the test soil sample in the soil sample installation area. A controllable drainage and liquid collection mechanism is located at the bottom of the test chamber and is connected to the lower water collection and diversion assembly for discharging seepage water. An axial consolidation loading mechanism is disposed above the test chamber and is used to apply a constant axial consolidation pressure to the sample assembly inside the test chamber. The in-situ shearing mechanism has its shearing actuator embedded inside the test soil sample in the soil sample installation area, and is used to perform in-situ shearing on the undisturbed soil sample. The data acquisition instrument is electrically connected to the stress sensor of the in-situ shearing mechanism and the pore pressure monitoring sensor in the test soil sample to simultaneously acquire shear torque, shear stress and pore water pressure.

2. The test device for shear strength of weathered granite soil under high-pressure seepage as described in claim 1, characterized in that, The test chamber includes a base and a transparent cylinder mounted on the base.

3. The test device for shear strength of weathered granite soil under high-pressure seepage as described in claim 1, characterized in that, The lower water collection and diversion component includes a lower permeable stone and a lower water collection chamber located above the lower permeable stone. The lower water collection chamber is a hollow pressure-bearing structure with uniformly distributed water distribution holes on its upper and lower surfaces.

4. The test device for shear strength of weathered granite soil under high-pressure seepage as described in claim 1, characterized in that, The upper water collection and equalization component includes an upper permeable stone and an upper water collection chamber located above the upper permeable stone. The upper water collection chamber is a hollow pressure-bearing structure with uniformly distributed water distribution holes on its lower surface.

5. The test device for shear strength of weathered granite soil under high-pressure seepage as described in claim 1, characterized in that, The high-pressure seepage control mechanism includes a high-pressure nitrogen tank and a constant-pressure water tank, wherein the high-pressure nitrogen tank is connected to the constant-pressure water tank to provide a constant pressure to the constant-pressure water tank, and the constant-pressure water tank is connected to the upper water collection and equalization component.

6. The test device for shear strength of weathered granite soil under high-pressure seepage as described in claim 1, characterized in that, The axial consolidation loading mechanism includes a rigid frame and a jack. The upper end of the jack abuts against the rigid frame, and the lower end abuts against the sample assembly through a pressure plate.

7. The test device for shear strength of weathered granite soil under high-pressure seepage as described in claim 1, characterized in that, The in-situ shearing mechanism includes a motor, a torque sensor, a drill rod, a cross shear plate, and a casing. The cross shear plate is pre-embedded in the test soil sample as the shearing execution end, and the casing is fitted onto the drill rod. The top of the sample assembly is provided with a water-stop pad that is compatible with the casing.

8. The test device for shear strength of weathered granite soil under high-pressure seepage as described in claim 7, characterized in that, The in-situ shearing mechanism is equipped with a lifting component to adjust the vertical position of the in-situ shearing mechanism.

9. A method for testing the shear strength of weathered granite soil under high-pressure seepage, characterized in that, include: S1. Close the controllable drainage and liquid collection mechanism, apply constant axial consolidation pressure to the soil sample through the axial consolidation loading mechanism, inject water into the upper water collection and equalization component to fully saturate the soil sample, and complete consolidation and saturation after the stress sensing data stabilizes. S2. Activate the controllable drainage and liquid collection mechanism, and apply a constant high-pressure seepage pressure to the soil sample through the high-pressure seepage control mechanism. Once the pore water pressure data is stable, establish a stable seepage erosion field. S3. Drive the in-situ shearing mechanism to rotate at a constant speed to perform undisturbed in-situ shearing on the undisturbed soil sample, and simultaneously collect shearing torque, shear surface normal stress and pore water pressure at the corresponding position. S4. Repeat the above test by changing the consolidation pressure and seepage pressure. Based on the effective stress principle and the calculation of multiple shear surface torque superposition, the shear strength parameters of the soil sample are obtained by linear fitting.

10. The method for testing the shear strength of weathered granite soil under high-pressure seepage according to claim 9, characterized in that, Step S4 includes: Based on the three effective shear surfaces formed by the cross shear plate in the in-situ shearing mechanism—the circular top surface, the circular bottom surface, and the cylindrical side surface—the effective shear stress and corresponding torque of each shear surface are calculated, and then superimposed to obtain the peak total torque. The formula for total torque is rearranged as follows: The linear form is based on the peak total torque corresponding to each consolidation pressure. The independent variables determined by the normal pressure on each shear surface and the pore water pressure A ,exist T - A Linear fitting in the coordinate system yields the soil sample's internal friction angle φ and cohesion c.

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