An apparatus capable of simulating rainfall infiltration side slope shear failure and a working method thereof

Abstract

The present application belongs to the technical field of geotechnical engineering test equipment, and relates to an instrument capable of simulating rainfall infiltration slope shear failure and a working method thereof. The instrument comprises a lower shear box and an upper shear box, the lower shear box is in communication with the inside of the upper shear box, the upper shear box is connected with the output end of a shear loading component, an axial loading component is arranged in the upper shear box, the lower shear box and the upper shear box are both communicated with a water supply device, an axial LVDT sensor, a shear LVDT sensor, a plurality of moisture sensors and a plurality of matric suction sensors are arranged, and the moisture sensors, the matric suction sensors, the axial LVDT sensor and the shear LVDT sensor are all connected with a data acquisition system. The present application can simulate the soil strength deterioration caused by the change of groundwater level and the slope shear failure caused by the change of effective stress, can carry out the creep shear failure and the experiment of effective stress reduction, and can realize the shear of the slope surface with different angles. The experimental data are comprehensive, and the conclusion is reliable.

Description

Technical Field

[0001] This invention belongs to the technical field of geotechnical engineering and geological engineering testing equipment, and relates to an instrument that can simulate the shear failure of a slope caused by rainfall infiltration and its working method. Background Technology

[0002] Many geological hazards in nature are related to soil shear failure, and these hazards are distributed on original slopes with varying gradients. Therefore, studying soil shear strength is crucial for deepening our understanding of landslides and similar geological hazards. The main causes of landslides are soil degradation and changes in effective stress due to rising groundwater levels and rainfall infiltration. Because indoor triaxial tests are small in scale and costly, they cannot reflect strength characteristics at the field scale. Therefore, large-scale direct shear tests are considered the most effective experimental method for reflecting field-scale shear strength.

[0003] Currently, the main shortcomings of large-scale direct shearing instruments are:

[0004] 1. Conventional large-scale direct shear tests are often conducted under a fixed volumetric water content, which cannot measure the changes in pore water pressure and volumetric water content during the shearing process. At the same time, they cannot simulate the soil strength degradation caused by rising groundwater level and surface rainfall intensity, as well as the soil shear failure caused by changes in effective stress.

[0005] 2. Conventional large-scale direct shear tests can only measure failure under increased shear stress, and cannot measure creep shear failure under self-weight or simulate real shear at different slopes. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide an instrument and its working method for simulating the shear failure of a slope caused by rainfall infiltration. The present invention can measure the changes in pore water pressure and volumetric water content during the shearing process, simulate the soil strength deterioration caused by changes in groundwater level and the slope shear failure caused by changes in effective stress, and conduct shear experiments on creep shear failure and reduction of effective stress. It can realize the shearing of soil with different slopes under its own weight.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention discloses an instrument for simulating the shear failure of a slope caused by rainfall infiltration. The instrument includes a lower shear box with an upper shear box mounted on it. The lower and upper shear boxes are internally connected. The upper shear box is connected to the output end of a shear loading component. A pressure sensor is located between the upper shear box and the output end of the shear loading component. An axial loading component is located on the top of the upper shear box. An axial LVDT sensor is located between the upper shear box and the axial loading component. A shear LVDT sensor is located between the lower and upper shear boxes. Both the lower and upper shear boxes are connected to a water supply device. Several moisture sensors and several matrix suction sensors are mounted on both the lower and upper shear boxes. The moisture sensors, matrix suction sensors, axial LVDT sensors, and shear LVDT sensors are all connected to a data acquisition system.

[0009] Furthermore, the lower shear box is fixedly mounted on the inclined plate, the inclined plate is movably connected to the base, a nut is movably mounted on the inclined plate, a threaded rod passes through the nut, and the threaded rod is movably connected to the base.

[0010] Furthermore, an angle measuring component is arranged at the connection between the base and the inclined plate.

[0011] Furthermore, the inclined plate is provided with a limiting component and a shearing loading component. The limiting component is fixedly connected to the upper shear box, and the limiting component and the shearing loading component are located on both sides of the lower shear box, respectively.

[0012] Furthermore, the shearing loading component includes a power unit, the output end of which is connected to an axial transmission device, which is connected to an upper shear box. A pressure sensor is provided between the axial transmission device and the upper shear box, and the power unit is fixedly mounted on the inclined plate.

[0013] Furthermore, the axial loading component includes a pressure plate located inside the upper shear box, a counterweight is arranged on the pressure plate, several through holes are opened on the pressure plate, and permeable stones are placed between the pressure plate and the experimental soil sample.

[0014] Furthermore, a sliding device is provided between the lower shear box and the upper shear box.

[0015] Furthermore, the bottom surface of the lower shear box has several through holes, and permeable stones are laid on the bottom surface of the lower shear box.

[0016] Furthermore, the water supply device includes a telescopic device, which is equipped with a graduated bucket. The graduated bucket is connected to the inner cavities of the lower shear box and the upper shear box respectively through a transparent flexible tube. A water volume adjustment device is provided at the connection between the graduated bucket and the transparent flexible tube.

[0017] Based on the above structure, this invention discloses a working method for an instrument that can simulate the shear failure of a rainfall-infiltrated slope, comprising the following steps:

[0018] Place the lower shear box and the upper shear box horizontally, put the experimental soil sample into the lower shear box and the upper shear box, and adjust the moisture content of the experimental soil sample through the water supply device.

[0019] To conduct creep shear failure of soil, axial pressure is applied to the experimental soil sample through an axial loading component. The angles of the lower and upper shear boxes with the horizontal plane are adjusted. The axial deformation data of the experimental soil sample at different angles are measured by an axial LVDT sensor. The shear deformation data of the experimental soil sample is measured by a shear LVDT sensor, and the data is transmitted to the data acquisition system until the experimental soil sample is destroyed.

[0020] To measure the undrained shear strength of soil, the soil sample is axially compressed using an axial loading device. After the soil sample has consolidated and stabilized, the shear loading device is activated. The shear deformation data of the soil sample is measured using a shear LVDT sensor, and the loading pressure data of the shear loading device is measured using a pressure sensor. The data is then transmitted to the data acquisition system.

[0021] Moisture and matrix suction data of the experimental soil samples were measured using a moisture sensor and a matrix suction sensor, and the data was transmitted to the data acquisition system.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The instrument of this invention includes a lower shear box, on which an upper shear box is arranged, with the interiors of the lower and upper shear boxes connected. A lateral shear force is applied to the experimental soil sample through the relative movement of the lower and upper shear boxes. The upper shear box is connected to the output end of a shear loading component, and a pressure sensor is installed between the upper shear box and the output end of the shear loading component. The pressure sensor measures the loading pressure of the shear loading component, which pushes the upper shear box to move laterally. An axial loading component is located at the top of the upper shear box, applying axial pressure to the experimental soil sample. An axial LVDT sensor is installed between the upper shear box and the axial loading component, measuring the axial deformation of the experimental soil sample. A shear LVDT sensor is installed between the lower and upper shear boxes, measuring the shear deformation of the experimental soil sample. Both the lower and upper shear boxes are connected to a water supply device, which is used to change the moisture content within the experimental soil sample. Both the lower and upper shear boxes are equipped with several moisture sensors and several matrix suction sensors. The moisture sensors measure the moisture content of the experimental soil sample, while the matrix suction sensors measure the matrix suction data within the sample. The moisture sensors, matrix suction sensors, axial LVDT sensors, and shear LVDT sensors are all connected to a data acquisition system. The data is comprehensively processed by this system, resulting in more accurate and reliable experimental conclusions. This invention can measure changes in pore water pressure and volumetric water content during shearing, simulate soil strength degradation caused by groundwater level changes and slope shear failure caused by changes in effective stress, and conduct experiments on creep shear failure and reduction in effective stress. Different slope shear angles can be achieved by changing the angle of the inclined plate. The experimental data are comprehensive, and the conclusions are reliable.

[0024] The method of this invention involves placing a lower shear box and an upper shear box horizontally, and placing experimental soil samples inside the lower and upper shear boxes. A water supply device is used to adjust the moisture content of the experimental soil sample from the lower shear box to simulate groundwater level changes. Similarly, a water supply device is used to adjust the moisture content of the experimental soil sample from the upper shear box to simulate rainfall infiltration. To simulate creep shear failure of the soil, axial loading components are used to apply axial pressure to the experimental soil sample, or it is allowed to withstand its own weight. After the experimental soil sample has consolidated and stabilized, the angles of the lower and upper shear boxes relative to the horizontal plane are adjusted. Axial LVDT sensors are used to measure the axial deformation data of the experimental soil sample at different angles, and shear LVDT sensors are used to measure the shear deformation data of the experimental soil sample. The data is transmitted to a data acquisition system. The angle of the inclined plate is adjusted until the experimental soil sample is damaged, thus enabling slope shear experiments at different angles. To determine the undrained shear strength of soil, an axial loading device is used to apply axial pressure to the experimental soil sample. After the soil sample has consolidated and stabilized, the shear loading device is activated. A shear LVDT sensor measures the shear deformation data of the soil sample, and a pressure sensor measures the loading pressure data of the shear loading device. The data are then transmitted to a data acquisition system. Similarly, a moisture sensor and a matrix suction sensor measure the moisture content and matrix suction data of the soil sample, and the data is also transmitted to the data acquisition system. This invention can determine changes in pore water pressure and volumetric water content during shearing, simulate soil strength degradation caused by changes in groundwater level and slope shear failure caused by changes in effective stress, and conduct experiments on creep shear failure under self-weight. It can also simulate shearing on slopes at different angles. The experimental data from this invention are comprehensive, and the conclusions are reliable. Attached Figure Description

[0025] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0026] Figure 2 This is the front view of the present invention.

[0027] The components include: 1. Base; 2. Inclined plate; 3-1. Threaded rod; 3-2. Nut; 4. Lower shear box; 5. Upper shear box; 6. Axial loading component; 6-1. Pressure plate; 6-2. Counterweight; 7. Shear loading component; 7-1. Power unit; 7-2. Axial transmission device; 7-3. Pressure sensor; 8. Water supply device; 8-1. Telescopic device; 8-2. Graduated bucket; 8-3. Transparent hose; 9. Moisture sensor; 10. Substrate suction sensor; 11. Axial LVDT sensor; 12. Shear LVDT sensor; 13. Angle measuring component; 14. Limiting component; 15. Experimental soil sample; 16. Permeable stone; 17. Limiting plate. Detailed Implementation

[0028] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0030] The present invention will now be described in further detail with reference to the accompanying drawings:

[0031] See Figure 1 , oneAn instrument for simulating shear failure of a slope due to rainfall infiltration includes a lower shear box 4, on which an upper shear box 5 is arranged. The lower shear box 4 and the upper shear box 5 are internally connected. The lower shear box 4 and the upper shear box 5 are used to hold an experimental soil sample 15, and a lateral shear force is applied to the experimental soil sample 15 through the lower shear box 4 and the upper shear box 5. The upper shear box 5 is connected to the output end of a shear loading component 7. A pressure sensor is installed between the upper shear box and the output end of the shear loading component to measure the loading pressure of the shear loading component. The shear loading component 7 is used to push the upper shear box 5 to move laterally. An axial loading component 6 is installed on the top of the upper shear box 5 to apply axial pressure to the experimental soil sample 15. An axial LVDT sensor 11 is installed between the upper shear box 5 and the axial loading component 6 to measure the axial deformation of the experimental soil sample 15. A shear LVDT sensor 12 is installed between the lower shear box 4 and the upper shear box 5 to measure the shear deformation of the experimental soil sample 15. Both the lower shear box 4 and the upper shear box 5 are connected to a water supply device 8, which is used to change the moisture content in the experimental soil sample 15. When water is added from the permeable stone 16 in the upper shear box 4, the strength degradation caused by rainfall infiltration is simulated. When water is added from the permeable stone 16 in the lower shear box 5, the soil strength degradation caused by changes in groundwater level and the slope shear failure caused by changes in effective stress are simulated. Both the lower shear box 4 and the upper shear box 5 are equipped with several moisture sensors 9 and several matrix suction sensors 10. The moisture sensors 9 are used to measure the moisture content in the experimental soil sample 15, and the matrix suction sensors 10 are used to measure the matrix suction data in the experimental soil sample 15. The moisture sensors 9, matrix suction sensors 10, axial LVDT sensors 11, and shear LVDT sensors 12 are all connected to a data acquisition system. The data is comprehensively processed by the data acquisition system, making the experimental conclusions more accurate and reliable. This invention can measure changes in pore water pressure and volumetric water content during shearing, simulate soil strength degradation caused by groundwater level changes and rainfall infiltration, and slope shear failure caused by changes in effective stress. It can conduct creep shear failure experiments under its own weight. By changing the angles of the lower shear box 4 and the upper shear box 5 relative to the horizontal plane, slope shearing at different angles can be achieved. This invention more closely reflects actual soil shear failure, providing comprehensive experimental data and reliable conclusions.

[0032] See Figure 1In another feasible embodiment of the present invention, the following modifications are made as appropriate. It includes a lower shear box 4, on which an upper shear box 5 is arranged. The lower shear box 4 and the upper shear box 5 are internally connected. The upper shear box 5 is connected to the output end of the shear loading component 7. A pressure sensor is provided between the upper shear box and the output end of the shear loading component to measure the loading pressure of the shear loading component. An axial loading component 6 is provided on the top of the upper shear box 5. An axial LVDT sensor 11 is provided between the upper shear box 5 and the axial loading component 6. A shear LVDT sensor 12 is provided between the lower shear box 4 and the upper shear box 5. Both the lower shear box 4 and the upper shear box 5 are connected to a water supply device 8. Several moisture sensors 9 and several matrix suction sensors 10 are provided on both the lower shear box 4 and the upper shear box 5. The moisture sensors 9, matrix suction sensors 10, axial LVDT sensors 11, and shear LVDT sensors 12 are all connected to a data acquisition system.

[0033] The lower shear box 4 and upper shear box 5 are used to hold the experimental soil sample 15. The shear loading component 7 is used to push the upper shear box 5 to move laterally. Lateral shear force is applied to the experimental soil sample 15 through the upper shear box 5. The axial loading component 6 is used to apply axial pressure to the experimental soil sample 15. The axial LVDT sensor 11 is used to measure the axial deformation of the experimental soil sample 15. The shear LVDT sensor 12 is used to measure the shear deformation of the experimental soil sample 15. The water supply device 8 is used to change the moisture content in the experimental soil sample 15 to simulate rainfall infiltration and groundwater level changes, thereby conducting soil strength degradation caused by groundwater level changes and slope shear failure experiments caused by effective stress changes. The moisture sensor 9 is used to measure the moisture content in the experimental soil sample 15, and the matrix suction sensor 10 is used to measure the matrix suction data in the experimental soil sample 15. The data acquisition system is used for comprehensive data processing.

[0034] During the experiment, the experimental soil sample 15 was placed inside the lower shear box 4 and the upper shear box 5. The water content of the experimental soil sample 15 was adjusted by the water supply device 8, changing the angle between the lower shear box 4 and the upper shear box 5. The axial loading component 6 applied axial pressure to the experimental soil sample 15. The axial deformation of the experimental soil sample 15 at different angles was measured by the axial LVDT sensor 11. By recording the shear force of the shear loading component, the shear creep experiment of the slope at different angles could be realized. The axial deformation of the experimental soil sample 15 at different angles was measured by the axial LVDT sensor 11, and the data was transmitted to the data acquisition system. After the experimental soil sample 15 was axially compressed by the axial loading component 6 and the consolidation deformation of the experimental soil sample 15 stabilized, the shear loading component 7 was activated to conduct the undrained shear strength test of the soil. The shear deformation of the experimental soil sample 15 was measured by the shear LVDT sensor 12, and the data was transmitted to the data acquisition system. This invention can measure the changes in pore water pressure and volumetric water content during shearing, simulate soil strength degradation caused by groundwater level changes and rainfall infiltration, and slope shear failure caused by changes in effective stress. It can conduct creep shear failure experiments under self-weight, and can realize shearing of slopes at different angles, which is more consistent with actual soil shear failure. The experimental data are comprehensive and the conclusions are reliable.

[0035] Example 1:

[0036] See Figure 1 This embodiment discloses an instrument that can simulate the shear failure of a slope caused by rainfall infiltration. It includes a lower shear box 4, with an upper shear box 5 arranged on top of the lower shear box 4. The lower shear box 4 and the upper shear box 5 are internally connected. The upper shear box 5 is connected to the output end of a shear loading component 7. A pressure sensor is provided between the upper shear box and the output end of the shear loading component. An axial loading component 6 is provided on the top of the upper shear box 5. An axial LVDT sensor 11 is provided between the upper shear box 5 and the axial loading component 6. A shear LVDT sensor 12 is provided between the lower shear box 4 and the upper shear box 5. Both the lower shear box 4 and the upper shear box 5 are connected to a water supply device 8. Several moisture sensors 9 and several matrix suction sensors 10 are provided on both the lower shear box 4 and the upper shear box 5. The moisture sensors 9, matrix suction sensors 10, axial LVDT sensors 11, and shear LVDT sensors 12 are all connected to a data acquisition system.

[0037] The lower shear box 4 is fixedly mounted on the inclined plate 2. The inclined plate 2 is movably connected to the base 1. A nut 3-2 is movably mounted on the inclined plate 2. A threaded rod 3-1 passes through the nut 3-2. The threaded rod 3-1 is movably connected to the base 1. When the threaded rod 3-1 is rotated, the nut 3-2 will slide up and down along the threaded rod 3-1. The nut 3-2 drives the inclined plate 2 to rotate around the connection between the inclined plate 2 and the base 1, thereby adjusting the angle of the inclined plate 2 and thus adjusting the angle of the lower shear box 4. This can simulate shear failure under the action of self-weight at different slopes.

[0038] See Figure 2 An angle measuring component 13 is arranged at the connection between the base 1 and the inclined plate 2 to facilitate precise angle adjustment.

[0039] The inclined plate 2 is equipped with a limiting component 14 and a shearing loading component 7. The limiting component 14 is fixedly connected to the upper shear box 5, and the limiting component 14 and the shearing loading component 7 are located on both sides of the lower shear box 4 and the upper shear box 5, respectively. The limiting component 14 is used to prevent the pressure weight on the upper shear box 5 from falling.

[0040] The shearing loading component 7 includes a power unit 7-1, the output end of which is connected to an axial transmission device 7-2, which is connected to an upper shear box 5. A pressure sensor 7-3 is provided between the axial transmission device 7-2 and the upper shear box 5. The power unit 7-1 is fixedly mounted on the inclined plate 2.

[0041] Example 2:

[0042] See Figure 1 This embodiment discloses an instrument that can simulate the shear failure of a slope caused by rainfall infiltration. It includes a lower shear box 4, with an upper shear box 5 arranged on top of the lower shear box 4. The lower shear box 4 and the upper shear box 5 are internally connected. The upper shear box 5 is connected to the output end of a shear loading component 7. A pressure sensor is provided between the upper shear box and the output end of the shear loading component. An axial loading component 6 is provided on the top of the upper shear box 5. An axial LVDT sensor 11 is provided between the upper shear box 5 and the axial loading component 6. A shear LVDT sensor 12 is provided between the lower shear box 4 and the upper shear box 5. Both the lower shear box 4 and the upper shear box 5 are connected to a water supply device 8. Several moisture sensors 9 and several matrix suction sensors 10 are provided on both the lower shear box 4 and the upper shear box 5. The moisture sensors 9, matrix suction sensors 10, axial LVDT sensors 11, and shear LVDT sensors 12 are all connected to a data acquisition system.

[0043] The axial loading component 6 includes a pressure plate 6-1 located inside the upper shear box 5. Counterweights 6-2 are arranged on the pressure plate 6-1. Changing the number of counterweights 6-2 allows adjustment of the axial loading force on the experimental soil sample 15. Several through holes are provided on the pressure plate 6-1. A permeable stone 16 is placed between the pressure plate 6-1 and the experimental soil sample 15. The permeable stone 16 prevents soil particles from clogging the through holes on the pressure plate 6-1 and allows for more uniform humidification of the sample.

[0044] Example 3:

[0045] See Figure 1This embodiment discloses an instrument that can simulate the shear failure of a slope caused by rainfall infiltration. It includes a lower shear box 4, with an upper shear box 5 arranged on top of the lower shear box 4. The lower shear box 4 and the upper shear box 5 are internally connected. The upper shear box 5 is connected to the output end of a shear loading component 7. A pressure sensor is provided between the upper shear box and the output end of the shear loading component. An axial loading component 6 is provided on the top of the upper shear box 5. An axial LVDT sensor 11 is provided between the upper shear box 5 and the axial loading component 6. A shear LVDT sensor 12 is provided between the lower shear box 4 and the upper shear box 5. Both the lower shear box 4 and the upper shear box 5 are connected to a water supply device 8. Several moisture sensors 9 and several matrix suction sensors 10 are provided on both the lower shear box 4 and the upper shear box 5. The moisture sensors 9, matrix suction sensors 10, axial LVDT sensors 11, and shear LVDT sensors 12 are all connected to a data acquisition system.

[0046] A sliding device is provided between the lower shear box 4 and the upper shear box 5 to reduce the friction between them.

[0047] The bottom surface of the lower shear box 4 has several through holes, and the bottom surface of the lower shear box 4 is covered with permeable stones 16.

[0048] Example 4:

[0049] See Figure 1 This embodiment discloses an instrument that can simulate the shear failure of a slope caused by rainfall infiltration. It includes a lower shear box 4, with an upper shear box 5 arranged on top of the lower shear box 4. The lower shear box 4 and the upper shear box 5 are internally connected. The upper shear box 5 is connected to the output end of a shear loading component 7. A pressure sensor 7-3 is provided between the upper shear box and the output end of the shear loading component. An axial loading component 6 is provided on the top of the upper shear box 5. An axial LVDT sensor 11 is provided between the upper shear box 5 and the axial loading component 6. A shear LVDT sensor 12 is provided between the lower shear box 4 and the upper shear box 5. Both the lower shear box 4 and the upper shear box 5 are connected to a water supply device 8. Several moisture sensors 9 and several matrix suction sensors 10 are provided on both the lower shear box 4 and the upper shear box 5. The pressure sensor 7-3, moisture sensor 9, matrix suction sensor 10, axial LVDT sensor 11, and shear LVDT sensor 12 are all connected to a data acquisition system.

[0050] The water supply device 8 includes a telescopic device 8-1, on which a graduated bucket 8-2 is mounted. The telescopic device 8-1 is used to adjust the height of the graduated bucket 8-2, thereby adjusting the flow rate of water infiltration. The graduated bucket 8-2 is connected to the inner cavities of the lower shear box 4 and the upper shear box 5 via a transparent flexible tube 8-3. A water flow regulating device is installed at the connection between the graduated bucket 8-2 and the transparent flexible tube 8-3 to regulate the infiltration rate.

[0051] Example 5:

[0052] See Figure 1 This embodiment discloses an instrument for simulating the shear failure of a slope caused by rainfall infiltration. It includes an inclined plate 2, a lower shear box and an upper shear box fixed on the inclined plate 2, a water supply device, a measurement system, and a loading device. The measurement system includes deformation measurement, suction force measurement, and water content measurement. The loading device includes shear loading, axial loading, and the inclined plate. The measurement system includes measurements of soil matrix suction, soil volumetric water content, and soil shear deformation and compression deformation. Soil matrix suction is measured using two matrix suction sensors 10, which measure the matrix suction of the soil in the upper and lower shear boxes respectively. Two water sensors 9 measure the volumetric water content of the soil in the upper and lower shear boxes respectively. Two holes slightly larger than the sensor probes are opened on the side of the shear box for easy sensor installation. The upper shear box is a rectangular steel frame without a lid or bottom.

[0053] The upper part of the shear box has a pressure plate 6-1 with the same area as the inside of the shear box. It can move up and down under the action of the axial loading component 6 to consolidate and pressurize the experimental soil sample 15, simulating the soil at different burial depths.

[0054] The upper surface of the pressure plate 6-1 inside the upper shear box has evenly distributed small holes. A layer of permeable stone covers the bottom of these holes to prevent soil particles from clogging them. The lower shear box also has evenly distributed small holes, and the upper surface of these holes is also covered with permeable stone to prevent soil particles from clogging them. The lower shear box is a bottomed rectangular structure welded from steel profiles and is fixed to the inclined plate 2 with bolts. A hinge device is installed at the longitudinal end of the inclined plate 2, connecting it to the base. A threaded rod 3-1 is movably connected to the base, and a handwheel is provided at one end of the threaded rod 3-1 for rotating it, thereby adjusting the angle of the inclined plate 2. The base is equipped with an instrument for measuring the tilt angle. A nut that can rotate with the angle of the threaded rod 3-1 passes through the lower part of the threaded rod 3-1. Rotatable shafts pass through the sides of the nuts on the inclined plate 2. The water supply device is a small graduated bucket with a T-junction at the bottom. One end of the T-junction is connected to the water supply end of the upper shear box via a transparent flexible tube to simulate rainfall infiltration. The other end of the T-junction is connected to the water supply end of the lower shear box via a transparent flexible tube to simulate the rise of the groundwater level. The bucket is placed on the telescopic device 8-1. A limiting plate 18 perpendicular to the upper shear box is installed at one end of the upper shear box 5 to fix the counterweight 6-2 on the pressure plate 6-1. A shearing loading component 7 is installed at the other end of the upper shear box along its length. The power source for the shearing loading component 7 is a servo motor. A pulley is installed between the upper and lower shear boxes to facilitate control of the shearing direction and reduce friction between them.

[0055] Compared with the prior art, the effective effects of the present invention are:

[0056] The tilting plate 2 of the device of the present invention can be adjusted in angle, and can conduct direct shear tests on instantaneous shear strength at different slopes, as well as creep shear failure behavior under gravity at different slopes, which is more suitable for the actual soil strength characteristics.

[0057] The upper and lower shear boxes of the present invention are connected to a water supply device, which can simulate the shear failure caused by soil strength deterioration and effective stress changes in slopes under the action of rising groundwater level and rainfall infiltration.

[0058] The device of this invention employs two LVDT sensors, several matrix suction sensors, and a moisture sensor 9, which can accurately measure the shear deformation of the experimental soil sample 15, the changes in matrix suction during the shearing process, and the changes in volumetric water content. It can be used to conduct large-scale direct shear experiments on unsaturated soil.

[0059] This invention employs motor servo control to adjust the shearing rate, allowing for adjustments based on actual conditions. It enables direct shearing experiments at different shearing rates, resulting in a high degree of automation and stability of the shearing apparatus. Consequently, experimental accuracy is enhanced.

[0060] Based on the above structure, the present invention also discloses a working method of an instrument that can simulate the shear failure of a rainfall infiltration slope, comprising the following steps:

[0061] Place the lower shear box 4 and the upper shear box 5 horizontally, and put the experimental soil sample 15 into the lower shear box 4 and the upper shear box 5. Adjust the moisture content of the experimental soil sample 15 through the water supply device 8.

[0062] To conduct creep shear failure of soil, axial pressure is applied to the experimental soil sample 15 through the axial loading component 6. After the experimental soil sample 15 has stabilized due to consolidation deformation, the angles of the lower shear box 4 and the upper shear box 5 with the horizontal plane are adjusted. The axial deformation data of the experimental soil sample 15 at different angles are measured by the axial LVDT sensor 11, and the shear deformation data of the experimental soil sample 15 is measured by the shear LVDT sensor 12. The data is then transmitted to the data acquisition system until the experimental soil sample 15 is destroyed.

[0063] To measure the undrained shear strength of soil, the axial loading component 6 is used to apply axial pressure to the test soil sample 15. After the consolidation deformation of the test soil sample 15 stabilizes, the shear loading component 7 is activated. The shear deformation data of the test soil sample 15 is measured by the shear LVDT sensor 12, and the loading pressure data of the shear loading component is measured by the pressure sensor 7-3. The data is then transmitted to the data acquisition system.

[0064] The moisture and matrix suction data of the experimental soil sample 15 were measured by the moisture sensor 9 and the matrix suction sensor 10, and the data were transmitted to the data acquisition system.

[0065] See Figure 1 In another feasible embodiment of the present invention, the following modifications are made as needed. The process includes the following steps: The lower shear box 4 and the upper shear box 5 are placed horizontally. An experimental soil sample 15 is placed inside the lower shear box 4 and the upper shear box 5. The water content of the experimental soil sample 15 is adjusted by a water supply device 8 to simulate changes in groundwater level. To perform creep shear failure of the soil, axial pressure is applied to the experimental soil sample 15 using an axial loading component 6. After the experimental soil sample 15 has consolidated and stabilized, the angles of the lower shear box 4 and the upper shear box 5 with the horizontal plane are adjusted. The axial deformation data of the experimental soil sample 15 at different angles is measured using an axial LVDT sensor 11, and the shear deformation data of the experimental soil sample 15 is measured using a shear LVDT sensor 12. The data is then transmitted to a data acquisition system until the experimental soil sample 15 is destroyed. This allows for shear experiments on slopes at different angles. To determine the undrained shear strength of soil, axial loading component 6 applies axial pressure to the experimental soil sample 15. After the soil sample 15 has consolidated and stabilized, shear loading component 7 is activated. Shear deformation data of the soil sample 15 is measured using shear LVDT sensor 12, and loading pressure data of the shear loading component is measured using pressure sensor 7-3. The data are then transmitted to the data acquisition system. Moisture and matrix suction data of the soil sample 15 are measured using moisture sensor 9 and matrix suction sensor 10, and the data is also transmitted to the data acquisition system. This invention can measure changes in pore water pressure and volumetric water content during shearing, perform unsaturated shearing of soil, simulate soil strength degradation caused by groundwater level changes and slope shear failure caused by effective stress changes, conduct creep shear failure experiments under self-weight, and achieve slope shearing at different angles. The working conditions of this invention are more consistent with actual working conditions, and key data during the experimental process are measured, resulting in comprehensive experimental data and reliable conclusions.

[0066] Example 6:

[0067] This embodiment discloses a working method for an instrument that can simulate the shear failure of a rainfall-infiltrated slope, including the following steps:

[0068] Step 1: First, prepare a soil sample with a predetermined moisture content;

[0069] Step 2: Adjust the inclined plate to be level, divide the soil sample into several layers according to the design requirements, and compact it under the shear box. During compaction, roughen each layer of soil.

[0070] Step 3: Place the upper shear box on the lower shear box, and then fill and compact the upper shear box in several layers according to the design requirements to complete the preparation of experimental soil sample 15;

[0071] Step 4: Insert the matrix suction sensor and moisture sensor into the sensor placement holes of the upper and lower shear boxes respectively, and place the pressure plate on the experimental soil sample 15 in the upper shear box.

[0072] Step 5: Connect the moisture sensor, matrix suction sensor, pressure sensor, and LVDT sensor to the data acquisition system respectively, and zero the sensors;

[0073] Step 6: Adjust the tilt plate that holds the shear box to the set angle.

[0074] To achieve creep shear failure of soil, different counterweights are loaded onto the pressure plate. Simply adjust the lower shear box to different angles to obtain creep shear failure of the soil.

[0075] To test the undrained shear strength of soil, load different weights onto the upper pressure plate. After the soil has consolidated and deformed and stabilized, start the shear loading component to shear at a certain shear rate.

[0076] Step 7: Based on the shear strength under different loading pressures, the internal friction angle and cohesion of the soil can be calculated according to the Mohr-Coulomb standard measurement.

[0077] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for operating an instrument capable of simulating shear failure of a rain-infiltrated slope, the instrument comprising a lower shear box (4), an upper shear box (5) arranged on the lower shear box (4), the lower shear box (4) and the upper shear box (5) being internally connected, the upper shear box (5) being connected to the output end of a shear loading component (7), a pressure sensor (7-3) being provided between the upper shear box (5) and the output end of the shear loading component (7), an axial loading component (6) being provided on the top of the upper shear box (5), and the upper shear box (5) being connected to the axial loading component (7). An axial LVDT sensor (11) is provided between the components (6), and a shear LVDT sensor (12) is provided between the lower shear box (4) and the upper shear box (5). The lower shear box (4) and the upper shear box (5) are both connected to the water supply device (8). Several moisture sensors (9) and several matrix suction sensors (10) are provided on the lower shear box (4) and the upper shear box (5). The moisture sensor (9), the matrix suction sensor (10), the axial LVDT sensor (11) and the shear LVDT sensor (12) are all connected to the data acquisition system. The lower shear box (4) is fixedly mounted on the inclined plate (2), and the inclined plate (2) is movably connected to the base (1). An angle measuring component (13) is arranged at the connection between the base (1) and the inclined plate (2). The axial loading component (6) includes a pressure plate (6-1), which is located inside the upper shear box (5). A counterweight (6-2) is arranged on the pressure plate (6-1), and several through holes are opened on the pressure plate (6-1). A permeable stone (16) is provided between the pressure plate (6-1) and the experimental soil sample (15). The water supply device (8) includes a telescopic device (8-1), on which a graduated bucket (8-2) is provided. The graduated bucket (8-2) is connected to the inner cavity of the lower shear box (4) and the upper shear box (5) through a transparent hose (8-3). A water volume adjustment device is provided at the connection between the graduated bucket (8-2) and the transparent hose (8-3). Its features are, The working method includes the following steps: Place the lower shear box (4) and the upper shear box (5) horizontally, and put the experimental soil sample (15) into the lower shear box (4) and the upper shear box (5). Adjust the moisture content of the experimental soil sample (15) through the water supply device (8). To perform creep shear failure of soil, the experimental soil sample (15) is axially pressurized by the axial loading component (6). After the experimental soil sample (15) has stabilized after consolidation deformation, the angles of the lower shear box (4) and the upper shear box (5) with the horizontal plane are adjusted. The axial deformation data of the experimental soil sample (15) at different angles are measured by the axial LVDT sensor (11). The shear deformation data of the experimental soil sample (15) is measured by the shear LVDT sensor (12), and the data is transmitted to the data acquisition system until the experimental soil sample (15) is destroyed. To measure the undrained shear strength of soil, the soil sample (15) is axially compressed by the axial loading component (6). After the soil sample (15) has stabilized due to consolidation deformation, the shear loading component (7) is activated. The shear deformation data of the soil sample (15) is measured by the shear LVDT sensor (12), and the loading pressure data of the shear loading component is measured by the pressure sensor (7-3). The data is then transmitted to the data acquisition system. The moisture data and matrix suction data of the experimental soil sample (15) were measured by the moisture sensor (9) and the matrix suction sensor (10), and the data were transmitted to the data acquisition system. The water supply device (8) adjusts the water content of the experimental soil sample from the lower shear box (4) to simulate groundwater level changes; the water supply device (8) adjusts the water content of the experimental soil sample from the upper shear box (5) to simulate rainfall infiltration.

2. The instrument for simulating shear failure of a slope due to rainfall infiltration as described in claim 1, characterized in that, A nut (3-2) is movably installed on the inclined plate (2), and a threaded rod (3-1) is inserted inside the nut (3-2). The threaded rod (3-1) is movably connected to the base (1).

3. The instrument for simulating shear failure of a slope due to rainfall infiltration as described in claim 1, characterized in that, The inclined plate (2) is provided with a limiting component (14) and a shear loading component (7). The limiting component (14) is fixedly connected to the upper shear box (5), and the limiting component (14) and the shear loading component (7) are located on both sides of the lower shear box (4).

4. The instrument for simulating shear failure of a slope due to rainfall infiltration as described in claim 3, characterized in that, The shearing loading component (7) includes a power unit (7-1), the output end of which is connected to an axial transmission device (7-2), the axial transmission device (7-2) is connected to an upper shear box (5), a pressure sensor (7-3) is provided between the axial transmission device (7-2) and the upper shear box (5), and the power unit (7-1) is fixedly mounted on the inclined plate (2).

5. The instrument for simulating shear failure of a slope due to rainfall infiltration as described in claim 1, characterized in that, A sliding device is provided between the lower shear box (4) and the upper shear box (5).

6. An instrument for simulating shear failure of a slope due to rainfall infiltration, as described in claim 3 or 5, characterized in that, The bottom surface of the lower shear box (4) is provided with several through holes, and the bottom surface of the lower shear box (4) is covered with permeable stone (16).

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