A True Triaxial Hydraulic Coupled Compression Test System and Method for Bulk Gangue

Abstract

A true triaxial hydraulic coupling compression test system and method for bulk gangue is disclosed, applicable to geotechnical engineering and coal mining testing. It mainly consists of four parts: a test device frame, a hydraulic servo system, a data management system, and an internally enclosed seepage compression system. The hydraulic servo system primarily includes a loading cylinder, a constant-speed, constant-pressure metering pump, and inlet and outlet oil pipes. The data management system mainly includes a displacement sensor, data cable, button control console, computer, pressure sensor, flow meter, piezometer, and spoke-type weighing sensor. The internally enclosed seepage compression system mainly includes an electrically controlled shut-off valve, a high-pressure water pump, a water storage tank, a force transmission plate, a pressure plate, an inlet pipe, an annular spray head, sliding needle rollers, a drain pipe, and heat-shrink bags. This system can autonomously set horizontal and vertical loading stresses, simulating the actual stress conditions of bulk gangue under hydraulic coupling, playing a crucial role in safe mining in deep mines and managing ground pressure in goaf areas.

Description

Technical Field

[0001] This invention relates to a true triaxial hydraulic coupling compression test system and method for bulk gangue, which can be used in geotechnical engineering and coal mining testing. Background Technology

[0002] After coal mining, numerous goaf areas of varying sizes are formed underground. These goaf areas not only pose significant safety hazards to production but also pose a huge potential threat to surface buildings and people's lives and property. Furthermore, because coal mining requires the excavation of numerous rock tunnels, the large amounts of waste rock discharged are left in the open, causing severe damage to the mining area environment, seriously affecting the growth and development of surface vegetation. Moreover, the unstable nature of waste rock piles makes them prone to landslides and dam failures. Using mined waste rock as backfill material to fill underground goaf areas can not only control surface subsidence above the goaf areas, effectively protecting the safety of surface buildings and underground workers, but also simultaneously solve the problems of waste rock occupying arable land and polluting the environment. In deep mines, waste rock can be directly used to fill goaf areas without leaving the mine shaft, significantly reducing backfilling costs, especially waste rock transportation costs. However, as a non-cohesive bulk material, gangue can move and compress the surrounding rock masses or coal pillars under the pressure of the overlying strata. Furthermore, the high-stress compression environment and groundwater seepage effects at deeper levels need to be considered. Therefore, understanding the compression characteristics of bulk gangue through triaxial hydraulic coupling tests is crucial for safe production in deep-well gangue backfilling mining. In addition, by selecting the optimal gangue gradation for backfilling goaf areas based on the triaxial compression deformation characteristics of bulk gangue with different particle size distributions, surface subsidence can be effectively controlled, achieving the best subsidence control effect.

[0003] Existing true triaxial testing equipment is mainly suitable for studying the compression deformation characteristics of rock specimens. For loose gangue, only uniaxial lateral confinement compression methods can be used for pseudo-triaxial compression tests. However, pseudo-triaxial tests do not match the stress conditions in the field, and the test results deviate from the field conditions. Furthermore, the presence of seepage water in the goaf also has a certain impact on the mechanical properties of loose gangue. Therefore, developing a true triaxial hydraulic coupling compression test system for loose gangue can help us to realistically simulate the stress conditions of loose gangue in the field under hydraulic coupling, making the test results closer to the actual field conditions. This is of great importance for safe mining in deep mines and for managing ground pressure in goaf areas. Summary of the Invention

[0004] To address the problems existing in the current technology and equipment, this invention provides a true triaxial hydraulic coupling compression test system and method for bulk gangue. The purpose is to use this system to conduct true triaxial hydraulic coupling compression tests on bulk gangue, and to study the compression law and compression deformation characteristics of bulk gangue with different particle sizes and different lithologies through the test.

[0005] The technical solution adopted to solve the above problems is that the present invention mainly consists of four parts: a test device frame, a hydraulic servo system, a data management system, and an internally closed seepage compression system. The test device frame is cylindrical and mainly consists of a top plate, support columns, and a bottom plate. The top and bottom plates are connected to the support columns by fixing pins and are placed vertically on the ground. The hydraulic servo system mainly consists of a loading cylinder, a constant speed and constant pressure metering pump, and inlet and outlet oil pipes. The loading cylinder mainly consists of a cylinder bushing, a cylinder piston, a cylinder cover, a reaction cylinder, a sealing flange, a connecting plate, an accumulator, and an electronically controlled servo system. The system comprises valves and other components; the cylinder bushing contains the cylinder piston and sealing flange, while the cylinder bushing also contains the cylinder cover and reaction cylinder. The cylinder cover is fixed to the top of the reaction cylinder with fixing bolts, and the reaction cylinder is fixed to a connecting plate, which is embedded in the support column of the test device. The constant speed and constant pressure metering pump is connected to the accumulator via inlet and outlet oil pipes. The accumulator is fixed to the outer end of the reaction cylinder and connected to the loading cylinder via high-temperature and high-pressure oil pipes and an electrically controlled servo valve. The electrically controlled servo valve is located on the inlet and outlet oil pipes and is connected to the button control console via a data cable. The data management system mainly consists of displacement sensors, data cables, a button control console, a computer, pressure sensors, and a flow meter. The system comprises a piezometer and a spoke-type load cell, among other components. The displacement sensor is positioned opposite the pressure plate within the cylinder piston. The pressure sensor is connected above to a connecting plate and below to a force transmission plate. The spoke-type load cell is connected below to the bottom plate of the test device frame and above to the force transmission plate. The flow meter is located inside the inlet pipe of the test device, and the piezometer is positioned within the loose gangue. The displacement sensor, pressure sensor, spoke-type load cell, flow meter, and piezometer are all connected to a control panel and a computer via data cables. The internally enclosed seepage compression system mainly consists of an electrically controlled shut-off valve, a high-pressure water pump, a water storage tank, a force transmission plate, a rigid-flexible composite pressure-bearing top plate, an inlet pipe, and a ring... The device consists of a spray nozzle, a rigid pressure-bearing vertical plate, a sliding needle roller, a drain pipe, a rigid pressure-bearing base plate, and heat shrink bags. The water inlet pipe is located inside the force transmission plate above the test device, with one end connected to a high-pressure water pump and the other end passing through the rigid-flexible composite pressure-bearing top plate and the heat shrink bag. A ring-shaped spray nozzle is located at the lower end of the water inlet pipe. The drain pipe is located inside the force transmission plate below the test device, with one end connected to a water tank and the other end passing through the rigid pressure-bearing base plate and the heat shrink bag. The electrically controlled shut-off valve is located inside the water inlet pipe and connected to the button control panel via a data cable. The rigid pressure-bearing vertical plate is connected to the force transmission plate, and the heat shrink bag is laid along the rigid pressure-bearing plate. Bulk gangue is evenly distributed inside the heat shrink bag to form a closed space.

[0006] Furthermore, four loading cylinders are installed in the horizontal direction of the test device, and one is installed in the vertical direction of the test device located above the device. There are no loading cylinders below the test device. Each loading cylinder is supplied with oil by a separate constant speed and constant pressure metering pump.

[0007] Furthermore, the constant speed and constant pressure metering pump has four loading modes: constant pressure mode, constant speed mode, manual mode, and position mode.

[0008] Furthermore, both the inlet pipe and the outlet pipe are made of rubber, and a longer portion of the inlet pipe is suspended inside the test device. Three inlet pipes are evenly arranged in the force transmission plate above the device, and three outlet pipes are evenly arranged in the force transmission plate below the device.

[0009] Furthermore, the joint of the rigid pressure-bearing vertical plate is arranged in an internal staggered manner, and sliding needle rollers are provided inside the rigid pressure-bearing vertical plate and the rigid pressure-bearing bottom plate.

[0010] Furthermore, the inner wall of the heat-shrink bag is coated with a waterproof material.

[0011] A true triaxial hydraulic coupling compression test method for granular gangue, employing the aforementioned true triaxial hydraulic coupling compression test system for granular gangue, includes the following steps:

[0012] Step 1: Place the bulk gangue evenly layer by layer in the middle of the rigid pressure-bearing vertical plate, and lay heat shrink bags on the rigid pressure-bearing bottom plate and the rigid pressure-bearing vertical plate at the front edge of the bulk gangue.

[0013] Step 2: After the bulk gangue is filled, use a heat shrink gun to heat the heat shrink bag, causing the heat shrink bag to shrink and wrap around the bulk gangue, water inlet pipe and drain pipe to form a sealed space.

[0014] Step 3: Start the displacement sensor, pressure sensor, flow meter, piezometer and spoke-type load cell, and use the computer to zero the values ​​of each measuring instrument.

[0015] Step 4: Use the button control console to open the electronically controlled servo valve on the oil pipe, and use the loading cylinder to preload the gangue. The preloading is carried out in a step-by-step cyclic loading manner, with the number of steps in the three directions being equal, to prevent the specimen from being crushed and to more accurately simulate the actual working conditions. The forces in the six directions of up, down, front, back, left and right are preloaded to 2% to 5% of the predetermined load value, and the system is checked for any faults or abnormalities.

[0016] Step 5: After preloading is complete, use the button control panel to open the electrically controlled shut-off valve on the water inlet pipe, and use the high-pressure water pump to provide a constant water pressure for the bulk gangue.

[0017] Step 6: Use a flow meter to measure the water flow rate into the bulk gangue, and use a piezometer to measure the osmotic pressure inside the bulk gangue. The measurement data are transmitted to the computer via a data cable.

[0018] Step 7: Use a computer to select the constant speed and constant pressure metering pump corresponding to the horizontal loading cylinder, and select a working mode from constant pressure mode, constant speed mode, manual mode and position mode according to the test purpose. The pressurized cylinder acts on the rigid pressure plate to load the bulk gangue in the horizontal direction.

[0019] Step 8: During the horizontal loading process, the displacement of the rigid bearing plate is recorded using a displacement sensor, and the horizontal force on the gangue is recorded using a pressure sensor. The data is transmitted to the computer via a data cable.

[0020] Step 9: After the horizontal loading is completed, use the computer to select the constant speed and constant pressure metering pump corresponding to the vertical loading cylinder, and select a working mode from constant pressure mode, constant speed mode, manual mode and position mode according to the test purpose. The pressurizing cylinder acts on the rigid-flexible composite pressure-bearing top plate to load the bulk gangue in the vertical direction.

[0021] Step 10: During the vertical loading process, the vertical force on the gangue is recorded using a spoke-type load cell, and the horizontal displacement and force on the gangue are recorded using a pressure sensor and a displacement sensor. The data is transmitted to the computer via a data cable.

[0022] Step 11: After the test, shut down the hydraulic servo system and the internal enclosed seepage compression system in sequence.

[0023] Step 12: Draw and analyze the horizontal position and stress of the gangue before and after vertical loading to study the compression deformation law of the gangue.

[0024] The beneficial effects of this invention are:

[0025] The constant-speed, constant-pressure metering pump in this invention offers four loading modes: constant pressure, constant speed, manual, and position, increasing the variety of test options and better meeting experimental needs. The hydraulic cylinder servo valve and water pump shut-off valve are all electrically controlled, allowing for speed adjustment via a button control panel, making the testing process faster and more convenient. Furthermore, this invention utilizes instruments such as displacement sensors, pressure sensors, spoke-type load cells, flow meters, and piezometers to extract test data in real time and transmit it to a computer for storage via data cable, facilitating data analysis after the experiment. Analysis: This invention utilizes a rigid pressure-bearing vertical plate, a rigid-flexible composite pressure-bearing top plate, a rigid pressure-bearing bottom plate, and a heat-shrink bag to form a sealed space, preventing water overflow during the test. In this invention, an annular spray head is installed at the lower end of the water inlet pipe, ensuring uniform water distribution to the bulk gangue and preventing uneven water distribution from affecting the measurement of physical and mechanical parameters. The rigid pressure-bearing vertical plate joints are arranged in an internally staggered manner, preventing mutual compression between the rigid pressure-bearing vertical plates during the test loading process and hindering the hydraulic cylinder loading. Furthermore, sliding needle rollers are arranged within the rigid pressure-bearing vertical plate and the rigid pressure-bearing bottom plate to reduce friction during movement.

[0026] This invention provides a true triaxial hydraulic coupling compression test system and method for bulk gangue. The device takes into account the compression environment of high-level stress and the influence of groundwater seepage on the mechanical properties of bulk gangue, making the test results more consistent with the actual situation. It has important guiding significance for safe mining in deep mines and the management of ground pressure in goaf areas. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a true triaxial hydraulic coupling compression test system and test method for granular gangue according to the present invention.

[0028] Figure 2 This is a front cross-sectional view of a true triaxial hydraulic coupling compression test system and test method for bulk gangue according to the present invention.

[0029] Figure 3 This is a cross-sectional view of the loading cylinder of a true triaxial hydraulic coupling compression test system and test method for bulk gangue according to the present invention.

[0030] Figure 4 This is a sectional view of the closed compression section of a true triaxial hydraulic coupling compression test system and test method for bulk gangue according to the present invention.

[0031] Figure 5 This is a top cross-sectional view of a true triaxial hydraulic coupling compression test system and method for bulk gangue according to the present invention.

[0032] In the diagram: 1-Test device frame; 1-1-Top plate of test device frame; 1-2-Test device support column; 1-3-Base plate of test device frame; 2-Loading cylinder; 2-1-Cylinder bushing; 2-2-Cylinder piston; 2-3-Cylinder cover; 2-4-Fixing bolt; 2-5-Reaction cylinder; 2-6-Sealing flange; 2-7-Connecting plate; 2-8-Accumulator; 2-9-Electrically controlled servo valve; 3-Displacement sensor; 4-Fixing pin; 5-Electrically controlled shut-off valve; 6-High-pressure water pump; 7-Water storage tank; 8-Data cable; 9-Button 10-Control panel; 11-Computer; 12-Constant speed and pressure metering pump; 13-Inlet and outlet oil pipes; 14-Pressure sensor; 15-Flow meter; 16-Enclosed compression section; 17-Force transmission plate; 18-Rigid-flexible composite pressure-bearing top plate; 19-Water inlet pipe; 10-Annular spray head; 10-Rigid pressure-bearing vertical plate; 11-Sliding needle roller; 12-Drainage pipe; 13-Rigid pressure-bearing bottom plate; 14-Heat shrink bag; 15-16-Bulk gangue; 17-Pivot wheel type weighing sensor. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the present invention is not limited to these embodiments.

[0034] In the description of this invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] like Figures 1-5 As shown, a true triaxial hydraulic coupling compression test system and test method for granular gangue mainly consists of four parts: test device frame 1, hydraulic servo system, data management system and internal closed seepage compression system.

[0037] like Figures 1-2 As shown, the test device frame 1 is cylindrical and consists of a test device frame top plate 1-1, a test device support column 1-2, and a test device frame bottom plate 1-3. The frame top plate and bottom plate are respectively connected to the test device support column 1-2 by fixing pins 4 and are placed vertically on the ground.

[0038] like Figures 1-5 As shown, the hydraulic servo system mainly consists of a loading cylinder 2, a constant speed and constant pressure metering pump 11, and inlet and outlet oil pipes 12. The loading cylinder 2 consists of a cylinder bushing 2-1, a cylinder piston 2-2, a cylinder cover 2-3, a reaction cylinder 2-5, a sealing flange 2-6, a connecting plate 2-7, an accumulator 2-8, and an electrically controlled servo valve 2-9. The cylinder piston 2-2 and the sealing flange 2-6 are located inside the cylinder bushing 2-1, while the cylinder cover 2-3 and the reaction cylinder 2-5 are located outside the cylinder bushing 2-1. The cylinder cover 2-3 is fixed to the reaction cylinder 2-5 by fixing bolts 2-4. The loading cylinder 2 is fixed to the connecting plate 2-7, which is embedded in the support column 1-2 of the test device.

[0039] It should be noted that, to realistically simulate the actual stress conditions on-site, four loading cylinders 2 are installed horizontally on the test apparatus, and one loading cylinder 2 is installed vertically at the top of the apparatus. There are no loading cylinders 2 at the bottom of the test apparatus. Each loading cylinder 2 is supplied with oil by a separate constant-speed and constant-pressure metering pump 11. Each metering pump has four loading modes: constant pressure mode, constant speed mode, manual mode, and position mode. In constant pressure mode, the metering pump automatically applies stress to a predetermined value by setting the triaxial stress magnitude, and maintains the stress constant after reaching the predetermined pressure. Constant speed mode controls the stress loading rate. Manual mode is mainly used for depressurization. Position mode mainly controls the deformation of the coal specimen. Various modes can be used interchangeably during the test to meet the experimental requirements. The constant speed and constant pressure metering pump 11 is connected to the accumulator 2-8 through the inlet and outlet oil pipes 12. The accumulator 2-8 is fixed to the outer end of the reaction cylinder 2-5 and is connected to the loading cylinder 2 through the high temperature and high pressure oil pipe and the electric servo valve 2-9. The electric servo valve 2-9 is located on the inlet and outlet oil pipes 12 and is connected to the button control console 9 through the data line 8. The button control console 9 can be used to control the opening and closing of the electric servo valve 2-9.

[0040] like Figures 1-5 As shown, the data management system mainly consists of a displacement sensor 3, a data cable 8, a button control panel 9, a computer 10, a pressure sensor 13, a flow meter 14, a piezometer 16, and a spoke-type load cell 17.

[0041] It is noted that the data management system utilizes various sensors for data acquisition, data transmission via data cables, and computer storage and analysis. The displacement sensor 3 is positioned opposite the pressure plate within the hydraulic cylinder piston 2-2, used to measure compression in different directions during the test. The pressure sensor 13 is connected above to the connecting plate 2-7 and below to the force transmission plate 15-1, allowing for the measurement of horizontal stress in the test apparatus. The spoke-type load cell 17 is connected below to the test apparatus frame base plate 1-3 and above to the force transmission plate 15-1, allowing for the measurement of horizontal stress in the test apparatus. Sensor 17 can measure the vertical stress of the test device; the flow meter 14 is located in the water inlet pipe 15-3 of the test device and is used to measure the water flow rate into the bulk gangue 15-10 during the test; the piezometer 16 is arranged in the bulk gangue 15-10 and is used to measure the osmotic pressure of the bulk gangue 15-10 during the test; the displacement sensor 3, pressure sensor 13, flow meter 14, piezometer 16 and spoke-type weighing sensor 17 are all connected to the button control console 9 and computer 10 through data cable 8. After the various data measured by the test are transmitted back to the computer, they can be analyzed graphically in a timely manner, which is convenient for remote control and analysis.

[0042] like Figures 1-5As shown, the internally enclosed seepage compression system, as the core part of the hydraulic coupling compression system, mainly consists of an electrically controlled shut-off valve 5, a high-pressure water pump 6, a water storage tank 7, a force transmission plate 15-1, a rigid-flexible composite pressure-bearing top plate 15-2, a water inlet pipe 15-3, an annular spray head 15-4, a rigid pressure-bearing vertical plate 15-5, a sliding needle roller 15-6, a drain pipe 15-7, a rigid pressure-bearing bottom plate 15-8, and a heat shrink bag 15-9.

[0043] It should be noted that three inlet pipes 15-3 are arranged inside the force transmission plate 15-1 above the test device. One end is connected to the high-pressure water pump 6, and the other end passes through the rigid-flexible composite pressure-bearing top plate 15-2 and the heat shrink bag 15-9, so that the water in the high-pressure water pump 6 flows to the bulk gangue 15-10 to provide water pressure for the test. The lower end of the inlet pipe 15-3 is equipped with a ring spray head 15-4 to disperse the water flow in all directions, so that the bulk gangue is evenly watered. Three drain pipes 15-7 are arranged inside the force transmission plate 15-1 below the test device. One end is connected to the water storage tank 7, and the other end passes through the rigid pressure-bearing bottom plate 15-8 and the heat shrink bag 15-9, so that the water flowing through the bulk gangue 15-10 is discharged into the water storage tank 7. Both the inlet pipe 15-3 and the drain pipe 15-7 are made of rubber, and a longer part of the inlet pipe 15-3 is suspended inside the device, which can be used with the test. The upper force transmission plate 15-1 of the device moves up and down; the electrically controlled shut-off valve 5 is arranged in the water inlet pipe 15-3 and connected to the button control panel 9 through the data cable 8, so as to facilitate the adjustment of the water flow according to the actual situation; the rigid pressure-bearing upright plate 15-5 is connected to the force transmission plate 15-1; the joints of each rigid pressure-bearing upright plate 15-5 are arranged in an internal staggered manner to avoid mutual squeezing between the rigid pressure-bearing upright plates 15-5 during the test loading process, which hinders the loading of the oil cylinder. Sliding needle rollers 15-6 are provided in the rigid pressure-bearing upright plate 15-5 and the rigid pressure-bearing base plate 15-8 to reduce the friction when the rigid pressure plate moves; the heat shrink bag 15-9 is laid along the rigid pressure plate, and the inner wall of the heat shrink bag 15-9 is coated with waterproof material. The loose gangue 15-10 is evenly arranged in the heat shrink bag 15-9 to form a closed space to prevent water from overflowing the device during the test.

[0044] A true triaxial hydraulic coupling compression test method for granular gangue, employing the aforementioned true triaxial hydraulic coupling compression test system for granular gangue, includes the following steps:

[0045] Step 1: Place the loose gangue 15-10 layer by layer evenly in the middle of the rigid pressure-bearing vertical plate 15-5, and lay heat shrink bags 15-9 on the front edge of the loose gangue 15-10 rigid pressure-bearing bottom plate 15-8 and the rigid pressure-bearing vertical plate 15-5.

[0046] Step 2: After the bulk gangue 15-10 is filled, use a heat shrink gun to heat the heat shrink bag 15-9, so that the heat shrink bag 15-9 shrinks and wraps around the bulk gangue 15-10, the water inlet pipe 15-3 and the drain pipe 15-7 to form a sealed space.

[0047] Step 3: Start the displacement sensor 3, pressure sensor 13, flow meter 14, piezometer 16 and spoke-type load cell 17, and use computer 10 to zero the values ​​of each measuring instrument.

[0048] Step 4: Use the button control console 9 to open the electronically controlled servo valve 2-9 on the oil pipe, and use the loading cylinder 2 to preload the gangue. The preloading adopts a step-by-step cyclic loading, with the number of steps in the three directions being equal, to prevent the specimen from being crushed and to more accurately simulate the actual working conditions. The forces in the six directions of up, down, front, back, left and right are preloaded to 2%~5% of the predetermined load value, and the system is checked for faults and abnormalities.

[0049] Step 5: After preloading is completed, use the button control panel 9 to open the electrically controlled shut-off valve 5 on the water inlet pipe 15-3, and use the high-pressure water pump 6 to provide a constant water pressure for the bulk gangue 15-10.

[0050] Step 6: Use flow meter 14 to measure the water flow rate into bulk gangue 15-10, use piezometer 16 to measure the osmotic pressure inside bulk gangue 15-10, and transmit the measurement data to computer 10 via data cable 8.

[0051] Step 7: Using computer 10, select the constant speed and constant pressure metering pump 11 corresponding to the horizontal loading cylinder 2, and select a working mode from constant pressure mode, constant speed mode, manual mode and position mode according to the test purpose. The pressurizing cylinder 2 acts on the rigid pressure plate 15-5 to load the loose gangue 15-10 in the horizontal direction.

[0052] Step 8: During the horizontal loading process, displacement sensor 3 is used to record the displacement of the rigid bearing plate 15-5, and pressure sensor 13 is used to record the horizontal force on the gangue. The data is transmitted to computer 10 via data cable 8.

[0053] Step 9: After the horizontal loading is completed, the computer 10 selects the constant speed and constant pressure metering pump 11 corresponding to the vertical loading cylinder, and selects a working mode from constant pressure mode, constant speed mode, manual mode and position mode according to the test purpose. The pressurizing cylinder 2 acts on the rigid-flexible composite pressure-bearing top plate 15-2 to load the bulk gangue 15-10 vertically.

[0054] Step 10: During the vertical loading process, the spoke-type load cell 17 is used to record the vertical force on the gangue, and the pressure sensor 13 and displacement sensor 3 are used to record the horizontal displacement and force on the gangue. The data is transmitted to the computer 10 through the data cable 8.

[0055] Step 11: After the test, shut down each working element in the hydraulic servo system and the internally enclosed seepage compression system in sequence.

[0056] Step 12: Draw and analyze the horizontal position and stress of the gangue before and after vertical loading to study the compression deformation law of the gangue.

[0057] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not limiting. Those skilled in the art can make various similar representations under the guidance of the present invention without departing from the spirit and claims of the present invention.

Claims

1. A bulk gangue true triaxial hydraulic coupling compression test system, characterized in that: The system is mainly composed of a test device frame (1), a hydraulic servo system, a data management system and an internal closed seepage compression system; the test device frame (1) is in a cylindrical shape, mainly comprising a test device frame top plate (1-1), a test device support column (1-2) and a test device frame bottom plate (1-3); the frame top plate and the frame bottom plate are connected with the test device support column (1-2) through fixed pins (4) respectively; the hydraulic servo system mainly comprises a loading oil cylinder (2), a constant-speed constant-pressure metering pump (11) and inlet and outlet oil pipes (12); the loading oil cylinder (2) is composed of an oil cylinder liner (2-1), an oil cylinder piston (2-2), an oil cylinder cover (2-3), a counterforce cylinder (2-5), a sealing flange (2-6), a connecting plate (2-7), an accumulator (2-8) and an electric control servo valve (2-9); the oil cylinder liner (2-1) is internally provided with the oil cylinder piston (2-2) and the sealing flange (2-6), and externally provided with the oil cylinder cover (2-3) and the counterforce cylinder (2-5); the oil cylinder cover (2-3) is fixed on the counterforce cylinder (2-5) through fixed bolts (2-4); the loading oil cylinder (2) is fixed on the connecting plate (2-7), and the connecting plate (2-7) is embedded in the test device support column (1-2); the data management system comprises a displacement sensor (3), a data line (8), a button console (9), a computer (10), a pressure sensor (13), a flowmeter (14), a seepage pressure gauge (16) and a spoke type weighing sensor (17); the displacement sensor (3) is arranged in the oil cylinder piston opposite to the pressure bearing plate; the pressure sensor (13) is connected with the connecting plate (2-7) above and connected with a force transmission (15-1) plate below; the flowmeter (14) is located in a test device water inlet pipe (15-3); the seepage pressure gauge (16) is arranged in the bulk solid gangue (15-10); the spoke type weighing sensor (17) is connected with the test device frame bottom plate (1-3) below and connected with the force transmission plate (15-1) above; the displacement sensor (3), the pressure sensor (13), the flowmeter (14), the seepage pressure gauge (16) and the spoke type weighing sensor (17) are connected with the button console (9) and the computer (10) through the data line (8); the internal closed seepage compression system is mainly composed of an electric control stop valve (5), a high-pressure water pump (6), a water storage tank (7), a force transmission plate (15-1), a rigid-flexible composite pressure bearing top plate (15-2), a water inlet pipe (15-3), a ring-shaped spray head (15-4) arranged at the lower end of the water inlet pipe, a rigid pressure bearing vertical plate (15-5), a sliding needle (15-6), a drain pipe (15-7), a rigid pressure bearing bottom plate (15-8) and a heat shrink bag (15-9); the water inlet pipe (15-3) is arranged in the force transmission plate (15-1) above the test device, connected with the high-pressure water pump (6) at one end and penetrates through the rigid-flexible composite pressure bearing top plate (15-2) and the heat shrink bag (15-9) at the other end.The drain pipe (15-7) is arranged in the force transmission plate (15-1) below the test device, one end of the drain pipe (15-7) is connected with the water storage tank (7), and the other end of the drain pipe (15-7) penetrates the rigid pressure bearing bottom plate (15-8) and the heat shrink bag (15-9); the rigid pressure bearing vertical plate (15-5) is connected with the force transmission plate (15-1); the heat shrink bag (15-9) is laid along the rigid pressure bearing plate; the rigid pressure bearing vertical plate, the rigid-flexible composite pressure bearing top plate, the rigid pressure bearing bottom plate and the heat shrink bag form a closed space, so that water overflow in the test process is prevented. The inner wall of the heat-shrinkable bag is coated with waterproof material, the bulk gangue (15-10) is uniformly arranged in the heat-shrinkable bag (15-9), the heat-shrinkable bag (15-9) is heated by a heat-shrinkable gun, the heat-shrinkable bag (15-9) is shrunk to wrap the bulk gangue (15-10), the water inlet pipe (15-3) and the water outlet pipe (15-7) to form a closed space; The water inlet pipe (15-3) is arranged in three in the force transfer plate (15-1) above the test device, one end is connected with the high-pressure water pump (6), the other end penetrates the rigid and flexible composite pressure bearing roof (15-2) and the heat-shrinkable bag (15-9), so that the water in the high-pressure water pump (6) flows to the bulk gangue (15-10) to provide water pressure for the test; The lower end of each water inlet pipe (15-3) is provided with the annular spray head (15-4) to disperse the water flow in all directions, so that the bulk gangue is uniformly subjected to water; The water inlet pipe (15-3) is made of rubber material, and a long part of the water inlet pipe (15-3) is suspended in the device and can move up and down with the force transfer plate (15-1) above; The water outlet pipe (15-7) is arranged in three in the force transfer plate (15-1) below the test device, one end is connected with the water storage tank (7), the other end penetrates the rigid pressure bearing bottom plate (15-8) and the heat-shrinkable bag (15-9), so that the water flowing through the bulk gangue (15-10) is discharged to the water storage tank (7).

2. The bulk gangue true triaxial hydraulic coupling compression test system according to claim 1, characterized in that: The loading oil cylinder (2) is arranged four in the horizontal direction of the test device and one in the vertical direction of the test device, located above the device.

3. The bulk gangue true triaxial hydraulic coupling compression test system according to claim 1, characterized in that: Each loading oil cylinder (2) is provided with an oil source by a separate constant-speed constant-pressure metering pump (11).

4. The bulk gangue true triaxial hydraulic coupling compression test system according to claim 1, characterized in that: The constant-speed constant-pressure metering pump (11) has four loading modes of constant pressure mode, constant speed mode, manual mode and position mode.

5. The bulk gangue true triaxial hydraulic coupling compression test system according to claim 1, characterized in that: The joint of the rigid pressure bearing vertical plate (15-5) is arranged in an inner staggered manner, and a sliding needle (15-6) is arranged in the rigid pressure bearing vertical plate (15-5) and the rigid pressure bearing bottom plate (15-8).

6. A bulk gangue true triaxial hydraulic coupling compression test method, using the bulk gangue true triaxial hydraulic coupling compression test system of any one of claims 1-5, characterized in that The method comprises the following steps: Step one: the bulk gangue (15-10) is uniformly placed in the middle of the rigid pressure bearing vertical plate (15-5) layer by layer, and the heat-shrinkable bag (15-9) is laid on the rigid pressure bearing bottom plate (15-8) and the rigid pressure bearing vertical plate (15-5) in front of the bulk gangue (15-10); Step two: after the bulk gangue (15-10) is filled, the heat-shrinkable bag (15-9) is heated by a heat-shrinkable gun, the heat-shrinkable bag (15-9) is shrunk to wrap the bulk gangue (15-10), the water inlet pipe (15-3) and the water outlet pipe (15-7) to form a closed space; Step three: start the displacement sensor (3), the pressure sensor (13), the flow meter (14), the osmotic pressure meter (16) and the spoke type weighing sensor (17), and use the computer (10) to zero the values of the measuring instruments. Step four: open the electric control servo valve (2-9) on the oil pipe by using the button console (9), and pre-load the gangue by using the loading cylinder (2). The pre-loading is loaded in steps and sequentially, and the number of steps in three directions is equal, so as to prevent the test piece from being damaged and more accurately simulate the actual working condition. The force in the six directions of up, down, front, back, left and right is pre-loaded to 2%-5% of the predetermined load value, and whether the system has faults and abnormal conditions is checked; Step five: after the pre-loading is completed, open the electric control stop valve (5) on the water inlet pipe (15-3) by using the button console (9), and use the high-pressure water pump (6) to provide a constant water pressure for the granular gangue (15-10); Step six: measure the water flow into the granular gangue (15-10) by using the flow meter (14), and measure the osmotic pressure in the granular gangue (15-10) by using the osmometer (16). The measurement data is transmitted to the computer (10) through the data line (8); Step seven: select the constant speed and constant pressure metering pump (11) corresponding to the horizontal loading cylinder (2) by using the computer (10), and select one working mode from the constant pressure mode, constant speed mode, manual mode and position mode according to the test purpose. The rigid pressure-bearing vertical plate (15-5) is loaded in the horizontal direction by using the pressurizing cylinder (2) to load the granular gangue (15-10); Step eight: during the horizontal loading process, the displacement of the rigid pressure-bearing vertical plate (15-5) is recorded by using the displacement sensor (3), and the horizontal force of the gangue is recorded by using the pressure sensor (13). The data is transmitted to the computer (10) through the data line (8); Step nine: after the horizontal loading is completed, select the constant speed and constant pressure metering pump (11) corresponding to the vertical loading cylinder by using the computer (10), and select one working mode from the constant pressure mode, constant speed mode, manual mode and position mode according to the test purpose. The rigid pressure-bearing vertical plate (15-5) is loaded in the horizontal direction by using the pressurizing cylinder (2) to load the granular gangue (15-10); Step ten: during the vertical loading process, the vertical force of the gangue is recorded by using the spoke type weighing sensor (17), and the displacement and force of the gangue in the horizontal direction are recorded by using the pressure sensor (13) and the displacement sensor (3). The data is transmitted to the computer (10) through the data line (8); Step eleven: after the test is completed, sequentially close the working elements in the hydraulic servo system and the internal closed seepage compression system; Step twelve: draw and analyze the horizontal position and force of the gangue before and after vertical loading, and study the compression deformation law of the gangue.

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