CN115541411A

CN115541411A - Large flexible boundary direct shear test system for researching shearing behavior of rock and soil mass

Info

Publication number: CN115541411A
Application number: CN202211061401.9A
Authority: CN
Inventors: 郑虎; 鲁天明; 戴国威; 黄雨
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2022-09-01
Filing date: 2022-09-01
Publication date: 2022-12-30

Abstract

The invention relates to a large flexible boundary direct shear test system for researching the shearing behavior of a rock and soil mass, which comprises a rigid frame, a shearing box, a horizontal loading system, a vertical loading system, a flexible boundary control system and a computer monitoring and management system. Compared with the traditional test device, the test system has the advantages of strong simulation capability, simple and convenient use, low economic cost and capability of truly reproducing the equal stress boundary conditions during unstable destruction of highly uneven rock and soil mass.

Description

Large-scale flexible boundary direct shear test system for researching shearing behavior of rock and soil mass

The technical field is as follows:

the invention relates to the field of engineering geology, in particular to a large flexible boundary direct shear test system for researching shearing behavior of a rock and soil mass.

Technical background:

in recent years, geological disasters such as landslide caused by unstable damage of rock and soil bodies cause huge loss to lives and properties of people, and meanwhile, disaster prevention and reduction measures cannot effectively play a role, so that the catastrophe mechanism of the geological disasters is not completely clear, and the intrinsic evolution mechanism of unstable damage of the rock and soil bodies is not clear. One of the difficulties causing the scientific research is the lack of a physical simulation means capable of truly reproducing the instability destruction boundary conditions of the rock and soil mass.

At present, three-axis tests and direct shear tests are mostly adopted in related research at home and abroad, and for rock-soil mechanical tests such as shear tests of rock-soil bodies, the boundary conditions of a loading end mainly comprise two conditions:

one is a uniform displacement boundary condition provided by a rigid boundary, such as the existing geotechnical mechanical test equipment such as a direct shear test device, but the rigid loading condition can cause the phenomenon of uneven stress distribution in the sample and on the shear surface in the shearing process, and can also cause the main stress direction to change, so that the difference between the measured shear strength of the preset shear surface and the actual stress state of the soil body is larger;

another is the uniform force boundary condition provided by a flexible boundary, such as a triaxial test device, but the principal stress direction of the triaxial compression test is fixed and the test is performed under the condition of axial symmetry, which is different from the actual condition of instability failure of rock-soil mass.

Therefore, the traditional rock-soil body testing device has the defects of the traditional rock-soil body testing device, and the stress and boundary conditions of the rock-soil body in the instability damage can not be truly reproduced, so that the research on the instability damage mechanism of the rock-soil body is greatly influenced. The existing research results show that the responses and strain distributions obtained by the uniform displacement boundary condition and the uniform force boundary condition of the material in the test are obviously different, the response obtained by the uniform displacement boundary is obviously higher than that obtained by the uniform force boundary condition, and the plastic strain distributions are also different. Displacement boundary conditions produce more densely and uniformly distributed slip bands, while stress boundary conditions produce more localized deformation fields. In addition, because the rock-soil body has high unevenness, the periphery of the geologic body cannot be equally displaced when the geologic body landslide disaster happens, and is closer to an equal stress boundary. Therefore, for the traditional rock-soil body indoor mechanical test, the equipotential boundary conditions of the rock-soil body indoor mechanical test are difficult to perfectly reproduce the real boundary conditions during the rock-soil body instability damage, and the influence on the research of the internal evolution mechanism of the rock-soil body instability damage is great. The rock-soil body mechanical test research under the flexible boundary condition is developed, and the rock-soil body mechanical test method can be developed into a test method and can also be used as theoretical supplement. However, such flexible boundary test conditions are not effectively applied to the research on landslide hazards of rock-soil mass, and for the reason, the uniform force boundary is difficult to simulate when the rock-soil mass is destabilized and damaged, so that a complete and effective test device is still lacking at present.

The technical difficulties of such test systems are:

(1) When a rock-soil body is tested, because rock blocks with larger grain sizes exist in the rock-soil body, the size of a shearing box in the traditional small and medium-sized shearing test is smaller, and the rock can not be smoothly shifted and turned, so that how to ensure that the rock blocks in the shearing process are still in a freely movable state when contacting with a test boundary is the first technical difficulty of the test system;

(2) The bottom of the traditional shear box adopts an undeformable rigid rectangular boundary, which can cause stress concentration of rock-soil mass at the rigid boundary during testing and limit the free development of a shear band, so how to ensure that a sample can be subjected to free deformation and can apply and maintain certain confining pressure is the second major technical difficulty of the testing system;

(3) The small and medium-sized direct shear test device is generally used as a soil body with small particle size and easy deformation for direct shear test due to small size of a shear box in the device, and rock and soil mass has high non-uniformity and rock mass with large particle size in the device, so that the generation of shear deformation of the rock and soil mass can be limited when the size of a shear surface is small, and therefore, the third technical difficulty of the test system is how to ensure that the rock and soil mass can still generate large deformation after being loaded;

(4) The bottom of a shearing box of the traditional large-scale direct shear test is a rigid bearing plate, and the boundary condition of a sample is an equal displacement boundary condition instead of an equal stress boundary condition where a natural rock-soil body is actually located, so that how to ensure that the lower boundary of the rock-soil body is in the actual equal stress boundary condition under the shearing action is the fourth major technical difficulty of the test system.

(5) The upper and lower shearing boxes can generate relative dislocation displacement in the shearing process, so that the rock and soil mass sample in the shearing box is easily extruded at the dislocation under the action of normal pressure of the upper bottom surface and the lower bottom surface, and therefore, how to ensure that the rock and soil mass is not extruded under the action of pressure in the shearing process is the fifth major technical difficulty of the test system.

The invention content is as follows:

in order to overcome the technical problems, the invention designs a large-scale flexible boundary direct shear test system for researching the shearing behavior of the rock-soil mass, the flexible direct shear test system adopts a square direct shear box with the size of 600 multiplied by 400 multiplied by 200mm, the size of the direct shear box is larger than that of a direct shear box in the traditional medium-scale and small-scale direct shear test system, and a small-scale metal box with an emulsion film is arranged at the bottom of the shear box, so that the flexible boundary condition of the rock-soil mass during deformation and instability damage is truly reproduced, the stress-strain relation of the rock-soil mass during instability and damage and the deformation development rule of a shear band are deeply researched, the internal mechanism of the rock-soil mass instability and damage is revealed, and a scientific basis is provided for the disaster prevention and reduction of the geological disasters.

The invention is realized by the following scheme:

a large flexible boundary direct shear test system for researching the shear behavior of a rock-soil body is characterized by comprising a rigid frame (1), a shear box (2), a horizontal loading system (3), a vertical loading system (4), a flexible boundary control system (5) and a computer monitoring management system (6);

the shear box (2) comprises an upper shear box and a lower shear box, is positioned in the rigid frame (1) and is used for loading rock and soil mass and carrying out shear loading;

the horizontal loading system (3) comprises a horizontal hydraulic jack (3-1) and a horizontal loading device, is positioned at the left side of the shear box in the rigid frame, and provides horizontal load for moving the lower shear box so as to shear the sample;

the vertical loading system (4) comprises a vertical hydraulic jack (4-3) and a pressure plate, and normal pressure is applied to the vertical hydraulic jack through the pressure plate to ensure that normal force of a sample is uniform;

the rigid frame (1) is positioned outside the shearing box (2) and the vertical hydraulic jack and is used for fixing the upper shearing box and preventing the upper shearing box from displacing in the shearing process;

the flexible boundary control system (5) comprises a sealed metal box (5-2), a hydraulic gauge (5-4), a pressure reducing valve (5-5), a hydraulic pump (5-6), a liquid output device (5-7) and a liquid recovery device (5-8) and is used for simulating real boundary conditions when the rock and soil body is unstably damaged; the metal box is arranged at the bottom of the lower shearing box and is provided with six surfaces, one surface is a latex film (5-1), and the other five side surfaces are metal plates, wherein the surface of the metal box, which is in contact with a rock-soil body sample in the lower shearing box, is the latex film (5-1), and the five side surfaces, which are in contact with the inner wall of the lower shearing box, are the metal plates; the two sides of the bottoms of the metal box and the lower shearing box are provided with openings which are connected with hoses; the opening on the left side close to the bottom is connected to a liquid recovery device (5-8) through a hose, the opening on the right side is respectively connected to a hydraulic pump and a liquid output device (5-7) through hoses, and the hose connected with the hydraulic pump is also connected with a hydraulic gauge and a pressure reducing valve; the liquid output device (5-7) is used for filling liquid into the metal box, the liquid recovery device (5-8) is used for recovering the liquid in the metal box, and the hydraulic pressure meter, the pressure reducing valve and the hydraulic pump are used for adjusting the liquid pressure in the metal box;

the computer monitoring and management system (6) is used for setting normal pressure during testing and monitoring the pressure change condition during the testing process; and by combining the sensors arranged in the horizontal loading system (3) and the vertical loading system (4), the output load is monitored in real time, and the stress-strain data of the rock-soil body in the shearing process is collected.

Further, the rigid frame (1) comprises a cross beam (1-1), a vertical column (1-2), a base (1-3), a horizontal pulley device (1-4) and an inner frame (1-5);

the cross beam (1-1) is fixed with the vertical hydraulic jack (4-3) to ensure that uniform vertical pressure is applied to a sample;

the upright post (1-2) is fixed with the cross beam (1-1) and used for offsetting the counter force generated by the vertical hydraulic jack;

the base (1-3) is used for fixing the upper frame and the shearing box (2), and the upright post (1-2), the inner frame (1-5) and the base (1-3) are fixed to form an integral frame, so that the integral displacement of the instrument in the test process is avoided;

the horizontal pulley devices (1-4) adopt two rows of pulleys and are respectively arranged on two sides of a bearing platform of the vertical shearing box.

Furthermore, the cross beam (1-1) is made of rigid materials, so that the strength is high, and the cross beam is prevented from being damaged by reverse pressure applied by a hydraulic jack; the upright columns (1-2) are made of aluminum alloy materials, so that the cross beam is effectively supported, the vertical pressure born by the cross beam is dispersed and transferred, and the cross beam is prevented from being jacked up by a vertical hydraulic jack; the base (1-3) is made of rigid materials, so that the weight of the base is increased, and the condition that the pedestal displaces or tilts during testing is avoided; the inner frames (1-5) are made of rigid materials.

Further, the shearing box (2) comprises an upper shearing box (2-1), a lower shearing box (2-2) and a ball shaft row (2-3);

the upper shearing box (2-1) is used for bearing the normal pressure applied by the hydraulic jack;

the lower shearing box (2-2) is used for connecting the horizontal loading device and applying a shearing action to the sample;

the left hinge seat (2-4) is arranged on the left side of the lower shearing box (2-2) and used for being connected with the horizontal loading device, and the lower shearing box (2-2) is hinged with the horizontal loading device;

the right side of the upper shearing box (2-1) is provided with a right hinge seat (2-5) for connecting an inner frame (1-5) of the rigid frame, and the upper shearing box and the rigid frame are fixed to prevent the upper shearing box and the rigid frame from moving;

the outer wall of the left side of the upper shearing box is provided with upper equal angle steel (2-6), the outer wall of the right side of the lower shearing box is provided with lower equal angle steel (2-7), and the upper equal angle steel (2-6) and the lower equal angle steel (2-7) are used for preventing rock and soil mass samples in the upper shearing box and the lower shearing box from being extruded out under the action of normal pressure in the shearing process;

the ball shaft row (2-3) is arranged at the bottom of the lower shearing box (2-2) and is used for horizontal shearing displacement of the lower shearing box under the action of external load.

Furthermore, the upper shearing box (2-1) and the lower shearing box (2-2) are made of high-strength rigid materials; the ball shaft rows (2-3) are paved into two rows by rollers, so that the lower shearing box can move in the horizontal direction; the left hinge seat (2-4) and the right hinge seat (2-5) are made of rigid materials.

Further, the horizontal loading system (3) is combined with an oil pump to apply horizontal load, so that the horizontal load can be continuously and stably applied to the lower shearing box, and comprises a horizontal hydraulic jack (3-1), a horizontal load sensor (3-2), a horizontal displacement sensor (3-3), a screw (3-4) and a variable-frequency speed reduction stabilizing device (3-5);

the horizontal hydraulic jack (3-1) is fixed on an inner frame (1-5) of the rigid frame and is connected with a variable-frequency speed reduction stabilizing device (3-5) through a screw rod (3-4), the horizontal load sensor (3-2) and the horizontal displacement sensor (3-3) are arranged on the screw rod (3-4), and the variable-frequency speed reduction stabilizing device (3-5) is connected with a left hinge seat (2-4) of the lower shearing box through a pin I (3-6);

the horizontal hydraulic jack (3-1) is combined with an oil pump to provide horizontal force for the lower shearing box; the horizontal load sensor (3-2) is used for monitoring the size of a horizontal output load; the horizontal displacement sensor (3-3) is used for monitoring the change condition of horizontal displacement; the screw rods (3-4) are used for transmitting horizontal loads; and the variable-frequency speed reduction stabilizing device (3-5) is used for controlling the size of the horizontal output load during unloading.

Furthermore, the vertical loading system (4) is combined with an oil pump to arrange a vertical pressure loading device, and comprises a vertical load sensor (4-1), a vertical displacement sensor (4-2), a vertical hydraulic jack (4-3) and a vertical force transmission movable base plate (4-4);

the vertical hydraulic jack (4-3) is fixed on a cross beam (1-1) of the rigid frame and used for outputting a vertical load; the vertical load sensor (4-1) and the vertical displacement sensor (4-2) are arranged on the vertical hydraulic jack (4-3) and used for monitoring the size of a vertical output load; the vertical force transmission movable base plate (4-4) is arranged between the inner frame (1-5) of the rigid frame and the upper shearing box and is used for uniformly transmitting the vertical pressure applied by the hydraulic jack to the sample;

the working principle of the vertical loading system is as follows: firstly, the output load size and frequency of a hydraulic jack (4-3) are set by computer control software, then a vertical load is applied to a vertical force transmission movable backing plate (4-4) by the hydraulic jack (4-3), the output vertical load size is monitored in real time by a vertical load sensor (4-1) and a vertical displacement sensor (4-2), and finally, vertical pressure is uniformly dispersed and transmitted to a sample by the vertical force transmission movable backing plate (4-4).

Furthermore, in the flexible boundary control system (5), the height of the metal box is about one third of that of the lower shearing box, the bottom area of the metal box is consistent with the inner bottom area of the lower shearing box, the metal box can be smoothly placed into the lower shearing box and can be fixed in the lower shearing, the metal box is prevented from moving, meanwhile, the latex film on the upper side of the metal box can also provide a flexible boundary condition for free movement of rock blocks in rock and soil bodies, and a sample is ensured to be in a uniform force boundary condition;

the two sides of the bottom of the metal box and the bottom of the lower shearing box are respectively provided with three openings for inserting hoses;

the opening at the upper end of the left side of the metal box is connected with a hose and is provided with a fourth hose switch (5-12) for exhausting air in the metal box; the opening at the lower end of the left side of the metal box is connected to a liquid recovery device (5-8) through a hose to collect liquid flowing out of the metal box after the test is finished, and a third hose switch (5-11) is arranged to turn on and off the liquid recovery;

the opening on the right side of the metal box is respectively connected with a liquid output device (5-7) and a hydraulic pump (5-6) through a hose and a three-way pipe; the liquid output device (5-7) fills liquid into the metal box with the emulsion film through the hose (5-3), and is provided with a first hose switch (5-9) for turning on and off liquid filling; the hydraulic pump (5-6) is connected with the metal box through a hose to pressurize the inner space of the metal box, a hydraulic gauge (5-4) and a pressure reducing valve (5-5) are arranged on the same section of hose, the hydraulic gauge (5-4) is used for displaying the pressure in the metal box, the pressure reducing valve (5-5) is used for adjusting the pressure in the metal box in the shearing process to ensure that the pressure of the metal box on a sample is unchanged, and a second hose switch (5-10) is further arranged to open and close the pressure input.

Further, the flexible boundary control system has the working principle that:

before the test is started, closing a second hose switch (5-10) close to one side of a pressure reducing valve and a third hose switch (5-11) close to a liquid recovery device, firstly, opening a first hose switch (5-9) and a fourth hose switch (5-12), filling liquid into the inner space of a metal box (5-1) with a latex film through a hose (5-3) by using a hydraulic output device (5-7), and closing the first hose switch (5-9) and the fourth hose switch (5-12) simultaneously when the liquid flowing out of the hose close to the hose switch (5-12) is observed, and then closing the liquid output device; secondly, opening a second hose switch (5-10), pressurizing liquid in the metal box by using a hydraulic pump (5-6), keeping the pressure output by the hydraulic pump (5-6) unchanged when the reading on a hydraulic gauge (5-4) reaches a pressure value specified by a test, and keeping the pressure in the metal box unchanged by adjusting a pressure reducing valve (5-5); finally, when the test is completed, the third hose switch (5-11) is opened slowly, and the liquid in the metal box (5-1) is released to the liquid recovery device (5-8).

Further, the work flow of the test system is as follows:

1) Firstly, moving a shearing box out of a rigid frame by using a horizontal pulley device, dismounting an upper shearing box, then placing a metal box with a latex film at the bottom of a lower shearing box, and confirming that the metal box is fixed at the bottom of the lower shearing box;

2) Respectively installing a hose and a hose switch on two sides of the bottom of the lower shearing box, installing a liquid recovery device on the left side, installing a liquid output device, a pressure reducing valve, a hydraulic meter and a hydraulic pump on the other side, and checking whether all joints are firmly connected or not, so that the liquid leakage in the test process is avoided, and the accuracy of the test result is prevented from being influenced;

3) Closing a hose switch close to one side of the pressure reducing valve and a hose switch at the lower part of the left side of the lower shearing box, opening the hose switch at the upper part of the left side of the lower shearing box and the hose switch at the liquid output device, filling liquid into the metal box through the liquid output device, closing the hose switch at the side when liquid flows out from the hose at the upper part of the left side of the lower shearing box, then closing the hose switch at the liquid output device, and filling liquid into the metal box at the moment;

4) The rock-soil mass sample prepared before the sample is loaded into a shear box in a layered mode, the quality and the filling height are controlled, a layered compaction method is adopted, the rock-soil mass sample has the same compactness in the initial state under each working condition, lubricating oil is smeared between an upper shear box and a lower shear box after the rock-soil mass sample is loaded, and the shear box is pushed into a rigid frame through a horizontal pulley device;

5) Respectively connecting a hinge seat on the left side of the lower shearing box with a horizontal loading device and connecting a hinge seat on the right side of the upper shearing box with a rigid frame by using pins, and determining whether the connection is stable and firm; a horizontal load sensor and a horizontal displacement sensor are arranged on the horizontal loading device;

6) A vertical force transmission movable base plate is placed in the center of the upper part of the upper shearing box, and the centers of the shearing box and the vertical force transmission movable base plate are ensured to be corresponding to the center of the vertical loading device; a vertical load sensor and a vertical displacement sensor are arranged on the vertical loading device;

7) Setting a normal pressure value required by a test in a computer monitoring and management system, starting a vertical loading device, slowly dropping a vertical hydraulic jack to make the vertical hydraulic jack fully contact with a vertical force transmission movable base plate, then controlling the loading speed, and keeping the pressure value unchanged after reaching a specified normal pressure value;

8) Starting the hydraulic pump when observingHydraulic pressure gaugeWhen the hydraulic reading reaches a specified pressure value, the hydraulic pump is closed, the hose switch close to one side of the pressure reducing valve is opened, the reading of the hydraulic meter is observed, and the pressure value of the liquid in the metal box is adjusted to be consistent with the set normal pressure value through the pressure reducing valve;

9) Starting a horizontal loading device, adjusting the loading rate of the horizontal loading device in the direct shear apparatus to a specified shearing rate and a specified shearing direction, and starting a shearing test; adjusting a monitoring management program on a computer to prepare for starting to acquire and monitor sensor data;

10 During shearing, close attention is paid to the hydraulic gaugeReading numberChanging, and adjusting the pressure reducing valve to enable the reading of the hydraulic gauge to be equal to the set normal pressure value, namely enabling the liquid pressure in the metal box to be consistent with the normal pressure value born by the upper shearing box (2-2);

11 Monitoring the reading changes of the horizontal load sensor (3-2) and the horizontal displacement sensor (3-3), judging that the sample is sheared when the reading of the horizontal load sensor (3-2) does not obviously rise or the reading of the horizontal displacement sensor (3-3) is rapidly increased in a load-displacement curve, stopping loading at the moment, stopping collecting data, and slowly returning the lower shearing box by using a horizontal variable-frequency speed reduction stabilizing device;

12 Closing the horizontal loading device and the vertical loading device, closing a hose switch and a hydraulic pump on one side close to the pressure reducing valve, opening the shear box, observing and recording the shear failure form of the rock-soil mass, and then cleaning the rock-soil mass in the shear box;

13 In a computer monitoring management system) the collected data is imported into a designated folder and saved, and then a next set of experiments is prepared to begin.

Compared with the prior art, the large-scale flexible boundary direct shear test system for researching the shearing behavior of the rock and soil mass has the following advantages:

(1) Boundary conditions of the rock-soil body in nature during destabilization and damage can be truly reproduced, and the real mechanical behavior characteristics of the rock-soil body during destabilization and damage can be reduced;

(2) The metal box with the latex film applies normal pressure required by a flexible boundary by filling liquid, so that test danger caused by filling gas by adopting a high-pressure gas cylinder can be effectively avoided;

(3) The latex film adopted by the invention can enable the rock-soil mass sample to deform freely in the shearing process, and can also apply normal pressure to the sample with a certain magnitude through hydraulic pressure in the metal box and maintain the normal pressure;

(4) The hydraulic pump adopted by the invention can effectively control the hydraulic pressure in the metal box, ensure that the sample is always in the same normal pressure state, avoid the change of the pressure borne by the sample caused by adopting a flexible boundary in the test process and ensure the accuracy of the test;

(5) The angle steel adopted in the test is connected with the upper shearing box and the lower shearing box, and can synchronously move along with the lower shearing box in the shearing process, so that the extrusion phenomenon of the sample at a dislocation position due to the action of normal pressure can be avoided;

(6) The test loading system can be controlled by corresponding test instruments, so that manual control operation is avoided, and test safety is effectively ensured;

(7) The test system is simple to assemble, economic and reliable, convenient to operate, capable of greatly improving the working efficiency and high in practicability.

Description of the drawings:

FIG. 1 is a general schematic diagram of an embodiment of a large flexible boundary direct shear test system for studying the shear behavior of a rock-soil mass according to the present invention;

FIG. 2 is a schematic view of the flexible border control system in the shear box of the detail of FIG. 1;

FIG. 3 is a schematic view of the detailed view of FIG. 1 showing the connection of the horizontal loading device to the lower shear box;

FIG. 4 is a schematic view of the horizontal pulley arrangement at the base of the detail view of FIG. 1;

fig. 5 is a flowchart of the operation of the test system of fig. 1.

Description of the labeling:

1-1 is a beam; 1-2 is a column; 1-3 is a base; 1-4 is a horizontal pulley device; 1-5 is an inner frame;

2-1 is an upper cutting box; 2-2 is a lower shear box; 2-3 is a ball shaft row; 2-4 is a left hinge seat; 2-5 is a right hinge seat; 2-6 are equal-angle steel; 2-7 is lower equal angle steel;

3-1 is a horizontal hydraulic jack; 3-2 is a horizontal load sensor; 3-3 is a horizontal displacement sensor; 3-4 is a screw; 3-5 is a frequency conversion speed reduction stabilizing device; 3-6 is a pin I; 3-7 is a pin II;

4-1 is a vertical load sensor; 4-2 is a vertical displacement sensor; 4-3 is a vertical hydraulic jack; 4-4 is a vertical force-transferring movable base plate;

5-1 is latex film; 5-2 is a metal box; 5-3 is a hose; 5-4 is a hydraulic gauge; 5-5 is a pressure reducing valve; 5-6 are hydraulic pumps; 5-7 is a liquid output device; 5-8 is a liquid recovery device; 5-9 is a first hose switch; 5-10 is a second hose switch; 5-11 is a third hose switch; 5-12 is a fourth hose switch;

5, a flexible boundary control system;

and 6, a computer monitoring management system.

The specific implementation mode is as follows:

the invention is described in detail below with reference to the figures and specific embodiments.

Example (b):

as shown in fig. 1, the large flexible boundary direct shear test system for studying the shear behavior of the rock-soil mass according to the present invention comprises:

rigid frame (1): and the upper shearing box is positioned outside the shearing box and the vertical hydraulic jack and used for fixing the upper shearing box and preventing the upper shearing box from displacing in the shearing process.

Shear box (2): and the device is positioned in the rigid frame and used for loading rock and soil mass and carrying out shear loading.

Horizontal loading system (3): the horizontal loading device is positioned on the left side of the shear box in the rigid frame and mainly provides a horizontal load for moving the lower shear box so as to shear a sample.

Vertical loading system (4): the device comprises a vertical hydraulic jack and a pressure plate, and is mainly used for applying normal pressure by the vertical hydraulic jack through the pressure plate so as to ensure that the normal stress of a sample is uniform.

Flexible border control system (5): the device comprises a sealed metal box, a hose, a switch, a hydraulic gauge, a pressure reducing valve and a hydraulic pump, and is used for simulating real boundary conditions when the rock-soil body is destabilized and damaged; the metal box has six surfaces, one surface contacting with the rock-soil body sample is an emulsion film, and the other five side surfaces are metal plates.

Computer monitoring management system (6): the device is positioned in computer software and is mainly used for setting normal pressure during testing, monitoring the pressure change condition during the testing process, and collecting stress and strain data of the rock and soil body in the shearing process in real time by combining load and displacement sensors arranged horizontally and vertically.

In particular, the rigid frame (1) comprises: the cross beam (1-1) is used for fixing the vertical hydraulic jack and ensuring that uniform vertical pressure is applied to the sample; the upright columns (1-2) are used for dispersing vertical pressure in a transfer test; the base (1-3) is used for fixing the upper frame and the shearing box and avoiding the displacement of the whole instrument in the test process; the horizontal pulley device (1-4) is used for moving out the shearing box after the test is finished and taking out the damaged sample in the shearing box; an inner frame (1-5) for fixing the horizontal hydraulic jack and the shear box; the upright post (1-2), the inner frame (1-5) and the base (1-3) are fixed to form an integral frame, so that the integral displacement of the instrument in the test process is avoided.

In particular, the shear box (2) comprises: an upper shear box (2-1) for bearing the normal pressure applied by the vertical hydraulic jack; the lower shearing box (2-2) is used for connecting the horizontal loading device and applying shearing action to the sample; the ball shaft rows (2-3) are used for horizontally shearing and displacing the lower shearing boxes under the action of external loads; the left hinge seat (2-4) is used for connecting the horizontal loading device; and the right hinge seat (2-5) is used for connecting the rigid frame. And the upper equal angle steel (2-6) and the lower equal angle steel (2-7) are used for preventing rock and soil mass samples in the upper shearing box and the lower shearing box from being extruded under the action of normal pressure in the shearing process. The angle steel is used for limiting the sample in the upper and lower shearing boxes from being extruded out under the action of normal pressure when the box is subjected to dislocation displacement. The angle steels on the two sides of the upper shearing box and the lower shearing box are respectively connected with the upper angle steel and the lower angle steel through bolts, so that the phenomenon that a sample in the shearing box is extruded in the shearing process is avoided.

Specifically, the horizontal loading system (3) mainly comprises a horizontal hydraulic jack (3-1) for providing horizontal output load; the horizontal load sensor (3-2) is used for monitoring the size of a horizontal output load; the horizontal displacement (3-3) is used for monitoring the change condition of the horizontal displacement; the screw rods (3-4) are used for transmitting horizontal loads; the variable-frequency deceleration stabilizing system (3-5) is used for controlling the size of a horizontal output load during unloading; the first pin (3-6) is used for connecting the screw rod and the lower shearing box, and the second pin (3-7) is used for connecting the upper shearing box and the rigid frame.

Specifically, the vertical loading system (4) mainly comprises a vertical load sensor (4-1) for monitoring the size of a vertical output load; the vertical displacement sensor (4-2) is used for monitoring the change condition of vertical displacement; the vertical hydraulic jack (4-3) is used for outputting a vertical load; the vertical force-transferring movable backing plate (4-4) is used for uniformly transferring the vertical pressure applied by the hydraulic jack to the sample.

Specifically, the flexible boundary control system (5) is used for providing a flexible boundary required by sample loading and ensuring that the sample is in a uniform force boundary condition; the hose (5-3) is used for inputting and outputting liquid into and out of the metal box with the emulsion film; the hydraulic gauge (5-4) is used for controlling the pressure in the metal box; the pressure reducing valve (5-5) is used for adjusting the pressure in the metal box in the shearing process and ensuring that the normal pressure applied to the sample is not changed; the hydraulic pump (5-6) is used to pressurize the inner space of the metal case. The liquid output device (5-7) is used for filling liquid into the metal box; the liquid recovery device (5-8) is used for collecting liquid flowing out of the metal box after the test is finished; the first hose switch (5-9), the third hose switch (5-11) are used for opening and closing the input and output of liquid, the second hose switch (5-10) is used for opening and closing the input and output of pressure, and the fourth hose switch (5-12) is used for exhausting air in the metal box.

The flexible boundary condition of this embodiment adopts the metal cassette that the one side is the emulsion membrane, and this metal cassette all the other five sides are the metal sheet, and the metal cassette height is about the third of the height of lower shear box, and the bottom surface area of metal cassette keeps unanimous with the interior bottom surface area of lower shear box, can guarantee like this that the metal cassette can put into smoothly under shear the box and can fix under shear in, prevent that the metal cassette from taking place to remove, the emulsion membrane of metal cassette upside also can provide the flexible boundary condition that can freely remove for the rock in the ground body simultaneously.

The latex film has good elasticity, and can ensure that the rock-soil body sample can be freely deformed and can apply and maintain certain confining pressure to the rock-soil body sample under the action of hydraulic pressure in the metal box.

The metal box is connected with an external hydraulic pump and a liquid output device through a hose, liquid is filled into the metal box through the hose on one side of the metal box, air in the metal box is discharged out of the other side of the metal box through a communicating hose, and when the liquid in the metal box is about to be filled, a switch of an exhaust outlet is closed, so that the liquid in the metal box is prevented from overflowing outwards, and the liquid pressurization in the metal box is prevented from being influenced.

The hydraulic pump is used for applying the normal pressure which is set in the test to the liquid in the metal box. When liquid in the metal box is nearly full, the liquid in rethread hydraulic pump and the intercommunication hose are to the liquid application pressure in the metal box, observe the reading of hydraulic pressure table simultaneously, when hydraulic pressure in the metal box reaches the normal pressure size of setting for, can close the switch of this side switch and hydraulic pump, can guarantee like this that the sample is in even confined pressure state, also can provide the equal stress boundary condition through emulsion membrane simultaneously.

Specifically, the computer monitoring and management system (6) is mainly used for setting normal pressure during testing, controlling a horizontal loading device and a vertical loading device, and monitoring the output load in real time and collecting stress and strain data of rock and soil bodies by combining sensors arranged in the horizontal loading system (3) and the vertical loading system (4), namely a horizontal load sensor (3-2), a horizontal displacement sensor (3-3), a vertical load sensor (4-1) and a vertical displacement sensor (4-2).

As shown in figure 2, the flexible boundary control system (5) comprises a latex film (5-1), a metal box (5-2), a hose (5-3), a hydraulic gauge (5-4), a pressure reducing valve (5-5), a hydraulic pump (5-6), a liquid output device (5-7), a liquid recovery device (5-8) and a hose switch (5-9-5-11). The metal box (5-2) with the latex film (5-1) is fixed at the bottom of the lower shearing box, and the metal box (5-2) is made of metal plates, so that the novel metal box has the advantages of easiness in assembly and portability. The two sides of the bottom of a metal box (5-2) with a latex film (5-1) and a lower shearing box (2-2) are respectively provided with drill holes with different diameters for inserting hoses (5-3), the hose at the upper part of the left side of the metal box and a fourth hose switch (5-12) are mainly used for exhausting air in the metal box when the metal box is filled with liquid, the hose at the lower part of the side and a third hose switch (5-11) are mainly used for exhausting the liquid in the metal box after a test is finished, the hose at the lower part of the right side of the lower shearing box and a second hose switch (5-10) are used for filling the liquid in the metal box, and the hose at the right part of the same side and a first hose switch (5-9) are used for pressurizing the metal box. The hydraulic pump (5-6) applies pressure to the metal box through the hose and keeps working continuously during the test. The hydraulic gauge (5-4) is used for monitoring the pressure of the liquid in the metal box. The pressure reducing valve (5-5), the hydraulic meter (5-4) and the hydraulic pump (5-6) are connected to the same section of hose (5-3) and are mainly used for adjusting the liquid pressure of the metal box (5-2) during testing, so that the normal pressure values of the upper part and the lower part of the rock and soil mass sample in the shear box are ensured to be the same. The liquid output device (5-7) is used for providing liquid filled in the metal box, and the liquid recovery device (5-8) is mainly used for receiving liquid discharged from the metal box after the test is finished.

As shown in figure 3, the horizontal loading system (3) is mainly combined with an oil pump to apply horizontal load, and comprises a horizontal hydraulic jack (3-1), a horizontal load sensor (3-2), a horizontal displacement sensor (3-3), a screw (3-4), a variable-frequency speed reduction stabilizing device (3-5), a first pin (3-6) and a second pin (3-7). The horizontal hydraulic jack is mainly combined with an oil pump to provide horizontal force for the lower shearing box, a horizontal load sensor (3-2) and a horizontal displacement sensor (3-3) are connected to a screw rod (3-4), the screw rod (3-4) is connected with a variable-frequency speed reduction stabilizing device (3-5), and meanwhile, the screw rod is connected with a left hinge seat (2-4) on the left side of the lower shearing box through a pin I (3-6), so that the horizontal load can be continuously and stably applied to the lower shearing box; when unloading is carried out after the test is finished, the frequency conversion speed reduction stabilizing device can effectively control the unloading speed, and the instrument is prevented from being damaged due to the too high unloading speed.

As shown in fig. 4, the horizontal pulley device (1-4) is composed of two rows of parallel roller groups, each row of roller groups comprises 6 rollers (2-3) which are respectively fixed on two sides of the base (1-3), and aluminum alloy upright posts (1-2) are respectively arranged on two sides of the base to fix the upper device, so that the upper device is prevented from displacement in the test process.

The control flow of the test system is as follows:

firstly, moving a shearing box out of the rigid frame, dismounting an upper shearing box, installing a metal box with a latex film in a lower shearing box, and installing and connecting other devices such as a hose, a switch and the like; secondly, filling liquid into the metal box through corresponding hoses and liquid output devices, closing all hose switches and the liquid output devices after filling, loading the prepared rock-soil mass sample into a shear box, and moving the rock-soil mass sample into a rigid frame; then, the shearing box is connected with a horizontal loading device through a hinge and a pin, and meanwhile, a vertical loading device is connected with the upper part of the shearing box through a vertical force transmission base plate and is fixed below the cross beam; secondly, monitoring a normal pressure value set by a management system by using a computer, applying normal pressure to the rock-soil mass in the shear box through a vertical jack and a hydraulic pump, and keeping the normal pressure value and the rock-soil mass in a working state when the normal pressure value reaches a specified value; and finally, carrying out shearing loading on the rock and soil mass sample in the shearing box through the horizontal loading device until the rock and soil mass sample is sheared and damaged, closing the corresponding loading device and the hose switch, stopping data acquisition, taking out the damaged rock and soil mass sample, and finishing the test.

In this embodiment, as shown in fig. 5, the specific application flow is as follows:

1) Firstly, a horizontal pulley device (1-4) is utilized to dismount a shearing box (2) outside a rigid frame (1), the shearing box (2-1) is moved out, then a metal box (5-2) with a latex film (5-1) is placed at the bottom of a lower shearing box (2-2), and the metal box (5-2) is confirmed to be fixed at the bottom of the lower shearing box (2-2);

2) Respectively installing a hose (5-3) and a hose switch (5-9-5-12) at two sides of the bottom of a lower shearing box (2-2), installing a liquid recovery device (5-8) at the left side, installing a liquid output device (5-7), a pressure reducing valve (5-5), a hydraulic gauge (5-4) and a hydraulic pump (5-6) at the other side, and checking whether each connection part is firmly connected or not, so that liquid leakage is avoided in the test process, and the accuracy of the test result is influenced;

3) Closing a second hose switch (5-10) close to one side of the pressure reducing valve and a fourth hose switch (5-12) at the lower part of the left side of the lower shearing box, opening a third hose switch (5-11) at the upper part of the left side of the lower shearing box and a first hose switch (5-9) at a liquid output device, filling liquid into the metal box (5-2) through the liquid output device (5-7), closing the third hose switch (5-11) at the left side when the liquid flows out from the hose at the upper part of the left side of the lower shearing box (2-2), and then closing the first hose switch (5-9) at the liquid output device, wherein the metal box is filled with the liquid;

4) The rock-soil mass sample prepared before the sample is loaded into a shear box (2) in a layered mode, the quality and the filling height are controlled, a layered compaction method is adopted, the rock-soil mass sample is guaranteed to have the same compactness in the initial state under each working condition, lubricating oil is smeared between an upper shear box and a lower shear box after the rock-soil mass sample is loaded, and the shear box (2) is pushed into a rigid frame (1) through a horizontal pulley device (1-4);

5) Connecting a left side hinge seat (2-4) of the lower shearing box with a horizontal loading device (3) by using a first pin (3-6), connecting a right side hinge seat (2-5) of the upper shearing box with a rigid frame (1) by using a second pin (3-7), and determining whether the connection is stable and firm; a horizontal load sensor (3-2) and a horizontal displacement sensor (3-3) are arranged on the horizontal loading device (3);

6) A vertical force transmission movable base plate (4-4) is placed in the center of the upper part of the upper shearing box, and the centers of the shearing box (2) and the vertical force transmission movable base plate (4-4) are ensured to be corresponding to the center of the vertical loading device (4); a vertical load sensor (4-1) and a vertical displacement sensor (4-2) are arranged on the vertical loading device (4);

7) Setting a normal pressure value required by a test in a computer monitoring and management system, starting a vertical loading device (4), slowly dropping a vertical hydraulic jack (4-3) to make the vertical hydraulic jack fully contact with a vertical force transmission movable base plate (4-4), then controlling the load loading rate of the hydraulic jack, and keeping the pressure value unchanged after the reading of a vertical load sensor reaches the set normal pressure value;

8) Starting a hydraulic pump (5-6), when observing that the hydraulic reading on a hydraulic gauge (5-4) reaches a specified normal pressure value, closing the hydraulic pump (5-6), starting a hose switch (5-10) close to one side of a pressure reducing valve, observing the reading of the hydraulic gauge (5-4), and adjusting through the pressure reducing valve (5-5) to enable the liquid pressure value in a metal box (5-2) to be consistent with the set normal pressure value;

9) Starting a horizontal loading device (3), adjusting the loading rate of the horizontal loading device (3) in the direct shear apparatus to a specified shearing rate and a specified shearing direction, and starting a shearing test; adjusting a monitoring management program on a computer to prepare for starting to acquire and monitor sensor data;

10 In the shearing process, the reading change of the hydraulic gauge is closely concerned, and the pressure reducing valve (5-5) is adjusted to enable the reading of the hydraulic gauge to be equal to the set normal pressure value, namely the liquid pressure in the metal box (5-2) is enabled to be consistent with the normal pressure value born by the upper shearing box (2-2);

11 Monitoring the reading changes of the horizontal load sensor (3-2) and the horizontal displacement sensor (3-3), and judging that the sample is sheared when the reading of the horizontal load sensor (3-2) does not obviously rise or the reading of the horizontal displacement sensor is sharply increased in a load-displacement curve; when the two conditions do not occur and the shearing displacement can be controlled to reach 40mm, the loading can be stopped, the data acquisition is stopped, the shearing loading is stopped, and the lower shearing box is slowly returned by utilizing a horizontal variable-frequency deceleration stabilizing device (3-5);

12 Closing the horizontal loading device (3) and the vertical loading device (4), closing a second hose switch (5-10) and a hydraulic pump (5-6) close to one side of the pressure reducing valve (5-5), opening the shear box (2), observing and recording the shear failure state of the rock-soil mass, and then cleaning the rock-soil mass in the shear box (2);

13 In the computer monitoring and management system (6) the collected data is imported into a designated folder and saved, and then the next set of tests is ready to be started.

Claims

1. A large flexible boundary direct shear test system for researching the shear behavior of a rock-soil body is characterized by comprising a rigid frame (1), a shear box (2), a horizontal loading system (3), a vertical loading system (4), a flexible boundary control system (5) and a computer monitoring management system (6);

the rigid frame (1) is positioned outside the shearing box (2) and the vertical hydraulic jack and used for fixing the upper shearing box and preventing the upper shearing box from displacing in the shearing process;

the flexible boundary control system (5) comprises a sealed metal box (5-2), a hydraulic gauge (5-4), a pressure reducing valve (5-5), a hydraulic pump (5-6), a liquid output device (5-7) and a liquid recovery device (5-8) and is used for simulating real boundary conditions when the rock and soil body is unstably damaged; the metal box is arranged at the bottom of the lower shearing box and is provided with six surfaces, one surface is a latex film (5-1), and the other five side surfaces are metal plates, wherein the surface of the metal box, which is contacted with a rock-soil body sample in the lower shearing box, is the latex film (5-1), and the five surfaces, which are contacted with the inner wall of the lower shearing box, are metal plates; the two sides of the bottom of the metal box and the bottom of the lower shearing box are provided with openings for connecting hoses; the opening on the left side close to the bottom is connected to a liquid recovery device (5-8) through a hose, the opening on the right side is respectively connected to a hydraulic pump and a liquid output device (5-7) through hoses, and the hose connected with the hydraulic pump is also connected with a hydraulic gauge and a pressure reducing valve; the liquid output device (5-7) is used for filling liquid into the metal box, and the liquid recovery device (5-8) is used for recovering the liquid in the metal box; the hydraulic gauge, the pressure reducing valve and the hydraulic pump are used for adjusting the liquid pressure in the metal box;

2. The large-scale flexible boundary direct shear test system for researching the shear behavior of rock and soil mass according to claim 1, wherein the rigid frame (1) comprises cross beams (1-1), upright columns (1-2), a base (1-3), horizontal pulley devices (1-4) and an inner frame (1-5);

the cross beam (1-1) is fixed with a vertical hydraulic jack (4-3) to ensure that uniform vertical pressure is applied to a sample;

the base (1-3) is used for fixing the upper frame and the shearing box, and the upright post (1-2), the inner frame (1-5) and the base (1-3) are fixed to form an integral frame, so that the integral displacement of the instrument in the test process is avoided;

3. The large-scale flexible boundary direct shear test system for researching the shear behavior of the rock-soil mass according to claim 2, wherein the cross beam (1-1), the base (1-3) and the inner frame (1-5) are made of rigid materials; the upright posts (1-2) are made of aluminum alloy materials.

4. The large-scale flexible boundary direct shear test system for researching the shear behavior of rock and soil mass according to claim 1, wherein the shear box (2) comprises an upper shear box (2-1), a lower shear box (2-2), a ball shaft row (2-3);

the lower shearing box (2-2) is used for connecting the horizontal loading device and applying shearing action to the sample;

5. The large-scale flexible boundary direct shear test system for researching the shear behavior of the rock-soil mass according to claim 4, wherein the upper shear box (2-1) and the lower shear box (2-2) are made of high-strength rigid materials; the ball shaft rows (2-3) are paved into two rows by adopting rollers, so that the lower shearing box can move along the horizontal direction; the left hinge seat (2-4) and the right hinge seat (2-5) are made of rigid materials.

6. The large-scale flexible boundary direct shear test system for researching the shear behavior of the rock-soil mass according to claim 1, wherein the horizontal loading system (3) is combined with an oil pump to apply horizontal load, so as to ensure that the horizontal load can be continuously and stably applied to the lower shear box, and comprises a horizontal hydraulic jack (3-1), a horizontal load sensor (3-2), a horizontal displacement sensor (3-3), a screw rod (3-4) and a variable-frequency deceleration stabilizing device (3-5);

the horizontal hydraulic jack (3-1) is combined with an oil pump to provide horizontal force for the lower shearing box; the horizontal load sensor (3-2) is used for monitoring the magnitude of a horizontal output load; the horizontal displacement sensor (3-3) is used for monitoring the change condition of horizontal displacement; the screw rods (3-4) are used for transmitting horizontal loads; and the variable-frequency speed reduction stabilizing device (3-5) is used for controlling the size of the horizontal output load during unloading.

7. The large-scale flexible boundary direct shear test system for researching the shear behavior of the rock-soil mass according to claim 1, wherein the vertical loading system (4) is combined with an oil pump to arrange a vertical pressure loading device, and comprises a vertical load sensor (4-1), a vertical displacement sensor (4-2), a vertical hydraulic jack (4-3) and a vertical force transmission movable base plate (4-4);

the working principle of the vertical loading system is as follows: the method comprises the steps of firstly setting the output load size and frequency of a hydraulic jack (4-3) by using a computer monitoring and management system, then applying a vertical load to a vertical force transmission movable base plate (4-4) by using the hydraulic jack (4-3), monitoring the output vertical load size in real time by using a vertical load sensor (4-1) and a vertical displacement sensor (4-2), and finally uniformly and dispersedly transmitting vertical pressure to a sample by using the vertical force transmission movable base plate (4-4).

8. The large flexible boundary direct shear test system for researching the shear behavior of the rock-soil mass according to claim 1, characterized in that in the flexible boundary control system (5), the height of the metal box is about one third of the height of the lower shear box, the bottom area of the metal box is consistent with the inner bottom area of the lower shear box, so as to ensure that the metal box can be smoothly placed into the lower shear box and can be fixed in the lower shear, prevent the metal box from moving, and simultaneously, the latex film on the upper side of the metal box can provide a flexible boundary condition for free movement for the rock blocks in the rock-soil mass, and ensure that the sample is in a uniform force boundary condition;

the hole at the upper end of the left side of the metal box is connected with a hose and is provided with a fourth hose switch (5-12) for removing air in the metal box; the open hole at the lower end of the left side of the metal box is connected to a liquid recovery device (5-8) through a hose to collect liquid flowing out of the metal box after the test is finished, and a third hose switch (5-11) is arranged to turn on and off liquid recovery;

the opening on the right side of the metal box is respectively connected with a liquid output device (5-7) and a hydraulic pump (5-6) through a hose and a three-way pipe; the liquid output device (5-7) fills liquid into the metal box with the latex film through a hose (5-3), and is provided with a first hose switch (5-9) for turning on and off liquid filling; the hydraulic pump (5-6) is connected with the metal box through a hose to pressurize the inner space of the metal box, a hydraulic gauge (5-4) and a pressure reducing valve (5-5) are arranged on the same section of hose, the hydraulic gauge (5-4) is used for displaying the pressure in the metal box, the pressure reducing valve (5-5) is used for adjusting the pressure in the metal box in the shearing process to ensure that the pressure of the metal box on a sample is unchanged, and a second hose switch (5-10) is further arranged to open and close the pressure input.

9. The large-scale flexible boundary direct shear test system for researching shearing behavior of rock and soil mass according to claim 8, wherein the working principle of the flexible boundary control system is as follows:

before the test is started, closing a second hose switch (5-10) close to one side of a pressure reducing valve and a third hose switch (5-11) close to a liquid recovery device, firstly, opening a first hose switch (5-9) and a fourth hose switch (5-12), filling liquid into the inner space of a metal box (5-1) with a latex film through a hose (5-3) by using a hydraulic output device (5-7), and closing the first hose switch (5-9) and the fourth hose switch (5-12) simultaneously when the liquid flowing out of the hose close to the hose switch (5-12) is observed, and then closing the liquid output device; secondly, opening a second hose switch (5-10), pressurizing liquid in the metal box by using a hydraulic pump (5-6), keeping the pressure output by the hydraulic pump (5-6) unchanged when the reading on a hydraulic gauge (5-4) reaches a pressure value specified by a test, and keeping the pressure in the metal box unchanged by adjusting a pressure reducing valve (5-5); finally, when the test is completed, the third hose switch (5-11) is slowly opened, and the liquid in the metal box (5-1) is released to the liquid recovery device (5-8).

10. The large-scale flexible boundary direct shear test system for researching the shear behavior of the rock-soil mass according to any one of claims 1 to 9, characterized in that the working process of the test system is as follows:

2) Respectively installing a hose and a hose switch on two sides of the bottom of the lower shearing box, installing a liquid recovery device on the left side, installing a liquid output device, a pressure reducing valve, a hydraulic meter and a hydraulic pump on the other side, and checking whether each joint is firmly connected or not, so that liquid leakage in the test process is avoided, and the accuracy of the test result is not influenced;

3) Closing a hose switch close to one side of the pressure reducing valve and a hose switch at the lower part of the left side of the lower shearing box, opening the hose switch at the upper part of the left side of the lower shearing box and the hose switch at the liquid output device, filling liquid into the metal box through the liquid output device, closing the hose switch at the side when liquid flows out from the hose at the upper part of the left side of the lower shearing box, and then closing the hose switch at the liquid output device;

4) Loading rock-soil body samples prepared before the samples into shear boxes in a layered mode, controlling quality and filling height, ensuring that the rock-soil body samples have the same compactness in the initial state under each working condition by adopting a layered compaction method, smearing lubricating oil between the upper shear box and the lower shear box after loading is finished, and pushing the shear boxes into a rigid frame through a horizontal pulley device;

8) Starting a hydraulic pump, when observing that a hydraulic reading on a hydraulic meter reaches a specified pressure value, closing the hydraulic pump, starting a hose switch close to one side of a pressure reducing valve, observing the reading of the hydraulic meter, and adjusting through the pressure reducing valve to enable the liquid pressure value in the metal box to be consistent with a set normal pressure value;

10 In the shearing process, the reading change of the hydraulic gauge is closely concerned, and the pressure reducing valve is adjusted to ensure that the reading of the hydraulic gauge is equal to the set normal pressure value, namely the liquid pressure in the metal box is kept consistent with the normal pressure value;