Chamber back pressure type ultra-large direct shear test device

Abstract

The utility model discloses a chamber back pressure type ultra-large direct shear test device, relates to the field of testing or analyzing materials by means of measuring the chemical or physical properties of the materials, and aims to realize full-level batching and sample preparation of rockfill materials and simulate the stress environment of an ultra-high dam rockfill body to carry out test research on the strength characteristics of the rockfill materials. According to the technical scheme, the chamber back pressure type ultra-large direct shear test device comprises an upper fixing base fixed to the top of a chamber and a lower pressing base fixed to the bottom of the chamber, and a vertically-arranged hydraulic device is hung at the bottom of the upper fixing base; a supporting plate is arranged at the top of the lower pressing base, a rolling device is arranged between the supporting plate and the lower pressing base, a lower shear box is placed on the top face of the supporting plate, an upper shear box is placed at the upper end of the lower shear box, a rolling device is arranged between the upper shear box and the lower shear box, and a counter-force support is arranged between the upper shear box and the side wall of the chamber. And a hydraulic device which is horizontally arranged is arranged between the lower shear box and the side wall of the chamber. The full-grading rockfill material direct shear test device is used for carrying out direct shear test on full-grading rockfill material samples.

Description

Technical Field

[0001] The utility model relates to the field of testing or analyzing materials by measuring the chemical or physical properties of materials, in particular to a device for testing the strength characteristics of solid materials with mechanical stress, specifically a super-large direct shear test device that uses a chamber back pressure to apply axial pressure and horizontal shear force. Background Technique

[0002] The direct shear test is a geotechnical test that places the soil under different vertical pressures, applies a horizontal shear force for shearing, and then determines the shear strength coefficient, internal friction angle, and cohesion of the soil according to Coulomb's law. The device commonly used for the direct shear test is a geotechnical direct shear apparatus. For direct shear tests on coarse-grained soils, a large geotechnical direct shear apparatus is required.

[0003] The existing large geotechnical direct shear apparatus includes a base, on which columns and a lower platen are arranged. Generally, there are two columns, and a crossbeam is connected between the two columns. A vertically arranged hydraulic jack and an upper platen are fixedly installed on the crossbeam. The specimen box is placed between the upper platen and the lower platen. The specimen box includes an upper shear box and a lower shear box. The column is also equipped with a horizontally arranged hydraulic jack, and the horizontally arranged hydraulic jack abuts against the upper shear box to apply a horizontal shear force to the upper shear box. The existing large geotechnical direct shear apparatus uses the vertically arranged hydraulic jack to apply a vertical pressure, and then uses the horizontally arranged hydraulic jack to apply a horizontal shear force to the upper shear box until the specimen in the specimen box is sheared. By applying different vertical pressures and repeating the test, the shear strength of the specimen can be measured.

[0004] The existing large geotechnical direct shear apparatus uses the columns to balance the reaction forces of the upper platen and the lower platen, and uses the columns to provide reaction forces for the horizontally arranged hydraulic jack. The maximum vertical pressure and horizontal shear force that can be applied are limited. The maximum horizontal shear force is about 310 kN, and the maximum vertical pressure is about 750 kN, which is applicable to specimens with a diameter of about 500 mm. The maximum allowable particle size of specimens with a maximum diameter of about 500 mm is about 100 mm.

[0005] The maximum particle size of the rockfill widely used in high earth-rock dams generally reaches 600 - 800 mm. The allowable particle size requirements of the existing large-scale geotechnical direct shear apparatuses for coarse-grained soil specimens are very different from the maximum particle size and particle gradation of the actual filled rockfill. For several currently proposed and under-construction 300m-class extra-high earth-rock dams, the maximum stress in the dam body exceeds 5 MPa. Exploring the mechanical strength characteristics of rockfill under such high confining pressures is the key to the design, construction, and safety evaluation of extra-high earth-rock dams. Therefore, there is an urgent need to develop a device that can conduct direct shear tests on full-graded rockfill with super-large sizes. The key to realizing such a device lies in the development of a test equipment system with super-large sizes, ultra-high pressures, easy operation, and meeting accuracy requirements, especially how to provide a reaction support for the hydraulic devices that apply ultra-high vertical pressures (such as 40000 kN) and horizontal shear forces (such as 20000 kN). Summary of the Invention

[0006] The present invention provides a chamber back-pressure type super-large direct shear test device, aiming to greatly increase the vertical pressure and horizontal shear force that can be applied in the direct shear test, realize the sample preparation of full-graded rockfill, and simulate the stress environment of the rockfill body of an extra-high dam to carry out experimental research on the strength characteristics of rockfill.

[0007] The technical solution adopted by the present invention is as follows: The chamber back-pressure type super-large direct shear test device includes an upper fixing seat fixed to the top of the chamber, and a lower pressing seat located at the bottom of the chamber and fixed directly below the upper fixing seat. At least one vertically arranged hydraulic device is suspended from the bottom of the upper fixing seat. Each vertically arranged hydraulic device is connected to a hydraulic station through an oil pipe, and the jacking direction of each vertically arranged hydraulic device is the vertical direction; a support plate is provided on the top of the lower pressing seat, a rolling device is provided between the lower pressing seat and the support plate, a lower shear box is placed on the top surface of the support plate, an upper shear box is placed on the upper end of the lower shear box. The top surface of the lower shear box and the bottom surface of the upper shear box are both horizontal planes. A rolling device is provided between the upper shear box and the lower shear box. A reaction support is provided between the upper shear box and the side wall of the chamber. One end of the reaction support is fixed to the side wall of the chamber, and the other end of the reaction support abuts against the upper shear box. At least one horizontally arranged hydraulic device is provided between the lower shear box and the side wall of the chamber. The jacking direction of each horizontally arranged hydraulic device is horizontal. Each horizontally arranged hydraulic device is connected to a hydraulic station through an oil pipe. One end of each horizontally arranged hydraulic device is fixed to the side wall of the chamber and the other end abuts against the lower shear box. The reaction support and the horizontally arranged hydraulic device are arranged on opposite sides of the upper shear box and the lower shear box; directly below the vertically arranged hydraulic device, there is an upper pressing seat fixedly connected or in abutting cooperation with it. The bottom surface of the upper pressing seat is a horizontal plane. The upper pressing seat is located inside the upper shear box. There is a clearance fit between the outer ring surface of the upper pressing seat and the inner wall of the upper shear box. The bottom surface of the upper pressing seat, the inner wall of the upper shear box, the inner wall of the lower shear box, and the top surface of the support plate together form a direct shear test cavity in the shape of a cylinder or a straight prism.

[0008] The rolling device between the upper shear box and the lower shear box is used to reduce the friction between the lower shear box and the upper shear box when the lower shear box moves horizontally. Further: multiple spherical segment-shaped grooves are provided on the bottom surface of the upper shear box or the top surface of the lower shear box, and ball bearings are provided in each groove; or the rolling device between the upper shear box and the lower shear box is a ball bearing bracket equipped with multiple ball bearings.

[0009] The rolling device between the lower pressing seat and the support plate is used to reduce the friction between the support plate and the lower pressing seat when the support plate moves horizontally. Further: multiple spherical segment-shaped grooves are provided on the top surface of the lower pressing seat or the bottom surface of the support plate, and ball bearings are provided in each groove; or multiple rollers are arranged between the lower pressing seat and the support plate, and the axial directions of the rollers are parallel to each other and perpendicular to the jacking direction of the horizontally arranged hydraulic device, and each roller is independent or connected into one body through a roller frame.

[0010] The direct shear test chamber is used to load the filling material that needs to be subjected to a direct shear test and conduct a direct shear test. Further: the upper shear box is an integral body, or is composed of at least two sections spliced in sequence in the vertical direction; the lower shear box is an integral body, or is composed of at least two sections spliced in sequence in the vertical direction. For example, the inner cavities of the upper shear box and the lower shear box are both cylindrical, the diameter of the cylinder is 3000mm, the height is 1500mm, and the upper shear box and the lower shear box are each composed of three sections spliced in sequence in the vertical direction.

[0011] In order to facilitate the movement of the lower pressing seat and the objects placed or installed on the lower pressing seat, further: at least two rows of traveling wheels are provided at the bottom of the lower pressing seat, each row of traveling wheels includes at least two traveling wheels, and the rows of traveling wheels are parallel to each other. Install tracks adapted to the traveling wheels at the bottom of the chamber, and place each row of traveling wheels on the corresponding track, then the lower pressing seat can be pushed to move in a predetermined direction by pushing.

[0012] In order to keep the directions of the loads applied by each vertically arranged hydraulic device to the upper pressing seat vertical, and the directions of the loads applied by each horizontally arranged hydraulic device to the upper shear box horizontal and parallel to each other, further: a spherical pressing seat is provided at the jacking end of each hydraulic device.

[0013] In order to make the space between the vertically arranged hydraulic device and the upper shear box larger, and the space between the horizontally arranged hydraulic device and the lower shear box larger, so as to facilitate test operation, further: a force transmission column or a force transmission frame is provided between the vertically arranged hydraulic device and the upper pressing seat, and a force transmission column or a force transmission frame is provided between the horizontally arranged hydraulic device and the lower shear box.

[0014] In order to ensure the stability of each horizontally arranged hydraulic device, further: a support frame is provided below each horizontally arranged hydraulic device.

[0015] In order to facilitate the acquisition of direct shear test data and control the process of the direct shear test, further: the chamber backpressure type ultra-large direct shear test device further includes a measuring device and a control system. The measuring device includes a force measuring device for monitoring the downward pressure of the upper pressure seat and the horizontal shear force of the horizontally arranged hydraulic device on the lower shear box. The measuring device also includes a displacement measuring device for monitoring the displacement of the upper pressure seat and the displacement of the lower shear box. The force measuring device and the displacement measuring device are both electrically connected to the control system, and the hydraulic station is also electrically connected to the control system.

[0016] The beneficial effects of the present utility model are as follows: The present utility model utilizes the top and bottom of the chamber to provide vertical reaction forces for each vertically arranged hydraulic device. The vertically arranged hydraulic device can be one or more, and the vertically arranged hydraulic device can apply an ultra-high total vertical pressure. The present utility model utilizes the side wall of the chamber to provide horizontal reaction forces for each horizontally arranged hydraulic device. The horizontally arranged hydraulic device can be one or more, and the horizontally arranged hydraulic device can apply an ultra-high total horizontal shear force. Since the present utility model can provide an ultra-high vertical pressure and horizontal shear force for the direct shear test, the size of the direct shear test chamber can be very large, and a direct shear test can be carried out on a full-graded rockfill sample with a particle size of 600 - 800 mm to test the mechanical parameters of the rockfill. In the present utility model, the upper shear box remains fixed, and the lower shear box is pushed by the horizontally arranged hydraulic device for the shear test, reducing the disturbance to the vertically arranged hydraulic device during the direct shear test, ensuring the safety of the direct shear test, and effectively controlling the shear plane. If the upper shear box moves and the lower shear box remains stationary, under the combined action of the vertical pressure and the horizontal shear force, during the high-stress shear process, the shear plane is prone to slide obliquely upward, and the upper shear box is prone to overturn. A rolling device is provided between the upper shear box and the lower shear box to avoid a large frictional force between the upper and lower shear boxes and reduce its influence on the test result data; a rolling device is also provided between the lower pressure seat and the support plate to similarly reduce the influence of the frictional force on the direct shear test result. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of an embodiment of the chamber backpressure type ultra-large direct shear test device of the present utility model.

[0018] Reference numerals: upper fixed seat 1, lower pressure seat 2, hydraulic device 3, support plate 4, rolling device 5, lower shear box 6, upper shear box 7, reaction support 8, upper pressure seat 9, traveling wheel 10, spherical pressure seat 11. Detailed Embodiments

[0019] The present utility model will be further described below with reference to the drawings.

[0020] As Figure 1As shown in the figure, the chamber backpressure type extra-large direct shear test device of the utility model includes an upper fixing seat 1 fixed to the top of the chamber, and a lower pressing seat 2 located at the bottom of the chamber and fixed directly below the upper fixing seat 1. At least one vertically arranged hydraulic device 3 is suspended from the bottom of the upper fixing seat 1. The upper fixing seat 1 is generally a steel frame and is fixed to the top of the chamber. The upper fixing seat 1 and the top of the chamber can provide a large enough reaction force for the vertically arranged hydraulic device 3. Each vertically arranged hydraulic device 3 is respectively suspended and installed on the upper fixing seat 1, and the jacking direction of each vertically arranged hydraulic device 3 is the vertical direction. The vertically arranged hydraulic devices 3 are generally multiple, that is, at least two, and the vertical load is applied in a group jacking manner. It is best that each vertically arranged hydraulic device 3 is the same for easy control. For example, there are five vertically arranged hydraulic devices 3, and the maximum jacking load of each vertically arranged hydraulic device 3 is 8000 kN, and the corresponding maximum total loading is 40000 kN. The maximum vertical stress applied to the specimen can reach 5.6 MPa. Each vertically arranged hydraulic device 3 is connected to a hydraulic station through an oil pipe, and a distributor is also provided on the oil pipe. The oil pipe includes an inlet oil pipe and a return oil pipe.

[0021] A support plate 4 is provided on the top of the lower pressing seat 2, and a lower shear box 6 is placed on the top surface of the support plate 4. The support plate 4 plays a direct supporting role for the lower shear box 6 and the specimen inside the lower shear box 6. To ensure the strength of the support plate 4, the support plate is generally a steel plate. A rolling device 5 is provided between the lower pressing seat 2 and the support plate 4. The rolling device 5 is used to reduce the friction force when relative displacement occurs between the lower pressing seat 2 and the support plate 4. For example, a plurality of spherical segment-shaped grooves are provided on the top surface of the lower pressing seat 2 or the bottom surface of the support plate 4, and ball bearings are provided in each groove. It is best that each groove is evenly distributed. Another example is that a plurality of rollers are provided between the lower pressing seat 2 and the support plate 4. The diameters of each roller are equal, the axial directions of each roller are parallel to each other and perpendicular to the jacking direction of the horizontally arranged hydraulic device 3, and each roller is independent or connected into a whole through a roller frame.

[0022] The upper shear box 7 is placed on the upper end of the lower shear box 6. The top surface of the lower shear box 6 and the bottom surface of the upper shear box 7 are both horizontal planes. A rolling device 5 is provided between the upper shear box 7 and the lower shear box 6. The rolling device 5 between the upper shear box 7 and the lower shear box 6 is used to reduce the friction force when relative displacement occurs between the upper shear box 7 and the lower shear box 6. Since the upper shear box 7 is relatively fixed, the rolling device 5 between the upper shear box 7 and the lower shear box 6 is used to reduce the resistance from the upper shear box 7 when the lower shear box 6 moves. In order to increase the contact area between the upper shear box 7 and the lower shear box 6 to facilitate the arrangement of the rolling device 5 between the upper shear box 7 and the lower shear box 6, annular wing plates can be respectively provided at the bottom of the upper shear box 7 and the top of the lower shear box 6, and the rolling device 5 is arranged between the wing plates of the upper shear box 7 and the wing plates of the lower shear box 6. For example, a plurality of spherical segment-shaped grooves are provided on the top surface of the upper shear box 7 or the bottom surface of the lower shear box 6, and ball bearings are provided in each groove, and each groove is preferably evenly distributed. For another example, the rolling device 5 between the upper shear box 7 and the lower shear box 6 is a ball bearing bracket equipped with a plurality of ball bearings, and the ball bearings are restricted within the ball bearing bracket to prevent the ball bearings from scattering.

[0023] A reaction support 8 is provided between the upper shear box 7 and the side wall of the chamber. One end of the reaction support 8 is fixed to the side wall of the chamber, and the other end of the reaction support 8 abuts against the upper shear box 7. The reaction support 8 is used to fix the upper shear box 7 and the specimen therein, and transfer the thrust of the horizontally arranged hydraulic device 3 to the side wall of the chamber. The reaction support 8 is generally a steel support. At least one horizontally arranged hydraulic device 3 is provided between the lower shear box 6 and the side wall of the chamber, and the jacking direction of each horizontally arranged hydraulic device 3 is horizontal. Each horizontally arranged hydraulic device 3 is connected to the hydraulic station through an oil pipe, and a distributor is also provided on the oil pipe. The oil pipe includes an inlet pipe and a return pipe. One end of each horizontally arranged hydraulic device 3 is fixed to the side wall of the chamber, and the other end abuts against the lower shear box 6. The horizontally arranged hydraulic device 3 can be one, or two or more. When there are two or more horizontally arranged hydraulic devices 3, the jacking directions of each horizontally arranged hydraulic device 3 are preferably parallel to each other. The horizontally arranged hydraulic device 3 and the lower shear box 6 can be directly abutted, or the hydraulic device 3 applies a horizontal shear force to the lower shear box 6 through a force transfer member. For example, in order to make the space between the horizontally arranged hydraulic device 3 and the lower shear box 6 larger, a force transfer column or a force transfer frame is provided between the horizontally arranged hydraulic device 3 and the lower shear box 6. In order to ensure the stability of each horizontally arranged hydraulic device 3, a support frame is also provided below each horizontally arranged hydraulic device 3. The horizontally arranged hydraulic device 3 is used to apply a horizontal shear force to the specimen through the lower shear box 6. For example, each horizontally arranged hydraulic device 3 can apply a horizontal shear force of up to 24000 kN. In order to make the direction of the total load applied by the horizontally arranged hydraulic device 3 to the lower shear box 6 remain horizontal and pass through the center line of the lower shear box 6, a spherical pressure seat 11 is provided at the jacking end of each horizontally arranged hydraulic device 3. The reaction support 8 is used to balance the horizontal shear force and keep the upper shear box 7 relatively fixed. The reaction support 8 and the horizontally arranged hydraulic device 3 are arranged on the opposite sides of the upper shear box 7 and the lower shear box 6. The horizontally arranged hydraulic device 3 is preferably arranged above the lower shear box 6, and the reaction support 8 is preferably arranged below the upper shear box 7.

[0024] A upper pressure seat 9 fixedly connected or in abutting fit with the vertically arranged hydraulic device 3 is provided directly below the vertically arranged hydraulic device 3. The upper pressure seat 9 can be fixedly installed at the lifting end of the vertically arranged hydraulic device 3 or can be not fixedly connected to the vertically arranged hydraulic device 3. The vertically arranged hydraulic device 3 jacks vertically downward and applies a vertical pressure to the specimen through the upper pressure seat 9. The vertically arranged hydraulic device 3 can directly apply a vertical pressure to the upper pressure seat 9 or can apply a vertical pressure to the upper pressure seat 9 with the aid of a force transmission member. In order to make the space between the vertically arranged hydraulic device 3 and the upper shear box 7 larger for easy operation, a force transmission column or a force transmission frame can be arranged between the vertically arranged hydraulic device 3 and the upper pressure seat 9. In order to keep the direction of the load applied by the vertically arranged hydraulic device 3 to the upper pressure seat 9 vertical, a spherical pressure seat 11 is provided at the jacking end of the vertically arranged hydraulic device 3. In order to ensure the strength of the upper pressure seat 9, the upper pressure seat 9 is made of steel structure. The top surface of the specimen is flat, so the bottom surface of the upper pressure seat 9 is a horizontal plane, enabling the upper pressure seat 9 to evenly apply a vertical load to the specimen. The upper pressure seat 9 is located inside the upper shear box 7, and there is a clearance fit between the outer ring surface of the upper pressure seat 9 and the inner wall of the shear box 6. The clearance between the outer ring surface of the upper pressure seat 9 and the inner wall of the shear box 6 should be as small as possible to prevent the specimen from being extruded through this clearance. The bottom surface of the upper pressure seat 9, the inner wall of the upper shear box 7, the inner wall of the lower shear box 6, and the top surface of the support plate 4 together form a direct shear test cavity in the shape of a cylinder or a straight prism. The direct shear test cavity is used to accommodate the fill material for the direct shear test.

[0025] The inner cavities of the upper shear box 7 and the lower shear box 6 are in the shape of a cylinder or a straight prism, generally cylindrical. The upper shear box 7 and the lower shear box 6 are used to load the fill material that needs to undergo a direct shear test and provide lateral confinement conditions. In order to ensure their strength, the upper shear box 7 and the lower shear box 6 are generally steel cylinders and are provided with strengthening structures. The upper shear box 7 and the lower shear box 6 can each be an integral body or can be respectively composed of at least two sections spliced in sequence along the vertical direction. For example, Figure 1 in the shown embodiment, both the upper shear box 7 and the lower shear box 6 are composed of three sections spliced in sequence along the vertical direction, and the adjacent two sections of the upper shear box 7 and the lower shear box 6 are firmly connected, for example, by multiple bolts. The upper shear box 7 and the lower shear box 6 being composed of at least two sections spliced in sequence along the vertical direction provides convenience for layered sample preparation and is conducive to controlling the sample preparation parameters. During the saturation and drainage processes of the specimen with an oversized size, the gap between the adjacent two sections of the upper shear box 7 and the lower shear box 6 can be used for water seepage. For the inner cavity sizes of the upper shear box 7 and the lower shear box 6, it is required that they can hold the fill material with a particle size of 800 mm. For example, the inner cavities of both the upper shear box 7 and the lower shear box 6 are cylindrical, with a diameter of 3000 mm and a height of 1500 mm. When the upper shear box 7 and the lower shear box 6 are composed of at least two sections spliced in sequence along the vertical direction, the sections forming the upper shear box 7 and the lower shear box 6 are preferably the same.

[0026] Before conducting a direct shear test using the chamber backpressure type extra-large direct shear test device, it is necessary to first excavate an underground chamber for the direct shear test. For example, two series-connected chambers, one large and one small, are excavated. The large chamber is a sample preparation room, and the small chamber is a direct shear test room. After the lower pressing seat 2, the upper shear box 7, and the lower shear box 6 are assembled in the large chamber, filling materials are loaded into the upper shear box 7 and the lower shear box 6 to prepare a sample. Then, the whole formed by the lower pressing seat 2, the upper shear box 7, the lower shear box 6, and the sample is moved into the small chamber for the direct shear test. To facilitate the movement of this whole, tracks are laid between the large chamber and the small chamber. There are at least two tracks and each track is parallel to each other. Each track is preferably horizontally arranged, and the tracks are generally steel rails. Correspondingly, at least two rows of running wheels 10 are provided at the bottom of the lower pressing seat 2. Each row of running wheels 10 includes at least two running wheels 10. Each row of running wheels 10 is parallel to each other. The running wheels 10 are adapted to the tracks, and the running wheels 10 are placed on the tracks. When moving this whole, it can be pushed into the direct shear test room by means of hydraulic jacking.

[0027] To facilitate obtaining the data of the direct shear test and controlling the process of the direct shear test, the chamber backpressure type extra-large direct shear test device further includes a measuring device and a control system. The measuring device includes a force measuring device and a displacement measuring device. The force measuring device is used to monitor the downward pressure of the upper pressing seat 9 and the pushing force of the horizontally arranged hydraulic device 3 on the lower shear box 6, that is, the force measuring device is used to monitor the vertical pressure and the horizontal shear force on the sample. A force measuring device is arranged between the vertically arranged hydraulic device 3 and the upper pressing seat 9. The force measuring device can be arranged at the upper end or the lower end of the force transmitting member, or can be arranged inside the force transmitting member. A force measuring device is arranged between the horizontally arranged hydraulic device 3 and the lower shear box 6. The force measuring device can be arranged at the end of the force transmitting member, or can be arranged inside the force transmitting member. The displacement measuring device is used to monitor the vertical displacement of the upper pressing seat 9 and the horizontal displacement of the lower shear box 6. The displacement measuring device can be installed on an object that is relatively fixed during the direct shear test, such as the chamber or the upper shear box 7. Both the force measuring device and the displacement measuring device are electrically connected to the control system, and the hydraulic station is also electrically connected to the control system. Each vertically arranged hydraulic device 3 can dynamically detect and feedback-adjust the high stress load, so as to achieve large-area balance and uniform distribution of the vertical pressure and accurately adjust and control. Each horizontally arranged hydraulic device 3 can dynamically detect and feedback-adjust the high stress load, so as to achieve balance and uniform distribution of the horizontal pressure and accurately adjust and control. The control system can dynamically feedback-adjust the loading parameters of each hydraulic device 3 according to the stress state of the sample. The loading stress and the deformation of the sample of each hydraulic device 3 are automatically recorded. After the test is completed, the test results can be automatically analyzed and charts can be drawn on the computer. The empty stroke of the jack in the early stage of test preparation is automatically operated and adjusted by the control system through the hydraulic station. The utility model controls the whole direct shear test to be automatically completed through the measurement and control system, improves the equipment efficiency, reduces the labor intensity of the test personnel, and makes the test results more accurate through high-precision step-by-step pressurization and pressure compensation.

Claims

1. Chamber back pressure type super large direct shear test device, characterized by: The utility model comprises an upper fixed seat (1) fixed to the top of the cavern, and a lower pressing seat (2) located at the bottom of the cavern and fixed directly below the upper fixed seat (1); at least one vertically arranged hydraulic device (3) is suspended at the bottom of the upper fixed seat (1); each vertically arranged hydraulic device (3) is connected to a hydraulic station through an oil pipe; and the lifting direction of each vertically arranged hydraulic device (3) is a vertical direction; a support plate (4) is provided at the top of the lower pressing seat (2); and a rolling device (5) is provided between the lower pressing seat (2) and the support plate (4). A lower shear box (6) is placed on the top surface of the support plate (4), an upper shear box (7) is placed on the upper end of the lower shear box (6), the top surface of the lower shear box (6) and the bottom surface of the upper shear box (7) are both horizontal planes, a rolling device (5) is provided between the upper shear box (7) and the lower shear box (6), a reaction force support (8) is provided between the upper shear box (7) and the side wall of the chamber, one end of the reaction force support (8) is fixed to the side wall of the chamber, the other end of the reaction force support (8) is in contact with the upper shear box (7), and the lower shear box (6) is in contact with the side wall of the chamber. At least one horizontally arranged hydraulic device (3) is arranged between the two sides. The lifting direction of each horizontally arranged hydraulic device (3) is horizontal. Each horizontally arranged hydraulic device (3) is connected to the hydraulic station through an oil pipe. One end of each horizontally arranged hydraulic device (3) is fixed to the side wall of the cavern and the other end is abutted against the lower shear box (6). The other end of the horizontally arranged hydraulic device (3) is abutted against the lower shear box (6). The reaction force support (8) and the horizontally arranged hydraulic device (3) are arranged between the upper shear box (7) and On opposite sides of the lower shear box (6); directly below the vertically arranged hydraulic device (3) is an upper pressure seat (9) fixedly connected or abutting therewith, the bottom surface of the upper pressure seat (9) is a horizontal plane, the upper pressure seat (9) is located inside the upper shear box (7), the outer ring surface of the upper pressure seat (9) and the inner wall of the upper shear box (7) are gap-matched, the bottom surface of the upper pressure seat (9), the inner wall of the upper shear box (7), the inner wall of the lower shear box (6) and the top surface of the support plate (4) together form a cylindrical or straight prism-shaped direct shear test cavity.

2. The chamber back pressure type super large direct shear test device according to claim 1, characterized in that: The bottom surface of the upper shear box (7) or the top surface of the lower shear box (6) is provided with a plurality of spherical grooves, each of which is provided with a ball; or the rolling device (5) between the upper shear box (7) and the lower shear box (6) is a ball bracket equipped with a plurality of balls.

3. The chamber back pressure type super large direct shear test device according to claim 1, characterized in that: The top surface of the lower pressure seat (2) or the bottom surface of the support plate (4) is provided with a plurality of spherical grooves, each of which is provided with a ball; or a plurality of rollers are arranged between the lower pressure seat (2) and the support plate (4), the axial directions of the rollers are parallel to each other and perpendicular to the lifting direction of the horizontally arranged hydraulic device (3), and the rollers are independent of each other or connected as a whole through a roller frame.

4. The chamber back pressure type super large direct shear test device according to claim 1, characterized in that: The upper shear box (7) is an integral part, or is formed by at least two sections spliced ​​in sequence along the vertical direction; the lower shear box (6) is an integral part, or is formed by at least two sections spliced ​​in sequence along the vertical direction.

5. The chamber back pressure type super large direct shear test device according to claim 4, characterized in that: The inner cavities of the upper shear box (7) and the lower shear box (6) are both cylindrical, with a diameter of 3000 mm and a height of 1500 mm. The upper shear box (7) and the lower shear box (6) are each composed of three sections spliced ​​in sequence along the vertical direction.

6. The chamber back pressure type super large direct shear test device according to claim 1, characterized in that: At least two rows of running wheels (10) are provided at the bottom of the lower pressing seat (2), each row of running wheels (10) comprises at least two running wheels (10), and the running wheels (10) in each row are parallel to each other.

7. The chamber back pressure type super large direct shear test device according to claim 1, characterized in that: A spherical pressure seat (11) is provided at the lifting end of each hydraulic device (3).

8. The chamber back pressure type super large direct shear test device according to claim 1, characterized in that: A force transmission column is also provided between the vertically arranged hydraulic device (3) and the upper pressure seat (9).

9. The chamber back pressure type super large direct shear test device according to claim 1, characterized in that: A support frame is also provided below each horizontally arranged hydraulic device (3).

10. The chamber back pressure type super large direct shear test device according to any one of claims 1 to 9, characterized in that: The chamber back-pressure type super-large direct shear test device also includes a measuring device and a control system. The measuring device includes a force measuring device for monitoring the downward pressure of the upper pressure seat (9) and the horizontal shear force of the horizontally arranged hydraulic device (3) on the lower shear box (6). The measuring device also includes a displacement measuring device for monitoring the displacement of the upper pressure seat (9) and the displacement of the lower shear box (6). The force measuring device and the displacement measuring device are both electrically connected to the control system, and the hydraulic station is also electrically connected to the control system.

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