Goaf filling gangue multi-scale rheological characteristic testing device and method

Abstract

The invention discloses a goaf filling gangue multi-scale rheological characteristic testing device and method.A loading pressing plate is arranged in a gangue pressurizing tank, the gangue pressurizing tank is divided into a rheological testing cavity and a pressurizing water cavity through the loading pressing plate, and the rheological testing cavity is used for containing gangue bulk solids; the water supply pressurization subsystem injects pressurized water into a pressurized water cavity to push a loading pressing plate to apply pressure to the gangue bulk, and gangue displacement data in the testing process is recorded through the gangue displacement monitoring subsystem; the gangue displacement monitoring subsystem can ensure the accuracy of data acquisition; the whole process does not need a press machine, the overall size is effectively reduced, and on-site layout in a goaf is achieved; the height of the rheology test cavity can be adjusted through the gas injection plate lifting subsystem, so that the test requirements of the gangue bulk solids with different heights can be met, meanwhile, the diameter of the gangue bulk solids can be adjusted in cooperation with the flexible sponge ring, and finally the rheology characteristic test of the gangue bulk solids with different heights and diameters is achieved. And data support is provided for evaluation of the control effect of the filling gangue on the stope surrounding rock.

Description

Technical Field

[0001] The invention belongs to the technical field of efficient development of coal mining resources and carbon emission reduction, and specifically relates to a device and method for testing multi-scale rheological properties of gangue filled in goaf. Background Art

[0002] The process of coal resource mining produces a large amount of waste coal gangue, which is randomly discharged or placed on the surface. The heat accumulation inside the gangue mountain may induce spontaneous combustion, and a large amount of gangue mountain occupies surface space resources and pollutes the environment. Therefore, the technology of filling goaf with gangue has been widely used in recent years. Filling the goaf with gangue can not only effectively dispose of the waste coal gangue, but also effectively control the surface subsidence.

[0003] The rheological properties of loose gangue in goaf filling (i.e., the time-dependent deformation properties produced under the continuous action of overburden stress) directly affect the stability of the surrounding rock in the goaf, and then affect the deformation of the surrounding rock, gas outburst in the adjacent coal seam, and the control effect of surface subsidence. Therefore, mastering the rheological properties of goaf gangue is of great significance for evaluating the control effect of goaf gangue filling stress field, gas flow field and fracture field. In addition, the rheological deformation of loose gangue has an obvious size effect, that is, the deformation of loose gangue under the same stress load is significantly related to its characteristic size (mainly the height and diameter of loose gangue). How to realize the multi-scale rheological property test of goaf filling gangue is the necessary bridge to build the laboratory scale test results and the actual situation of the field engineering scale. At present, the gangue rheological test is realized by loading the gangue bulk in the cylinder of customized size by servo press. However, due to the limitation of the size of the press plate, base and the inner diameter of the cylinder, it is difficult to realize the multi-scale rheological test of gangue, which leads to the blind evaluation of the control effect of filling gangue on the surrounding rock of the mine. In addition, the press required for pressure application is large and cannot be installed and arranged in a small space, so it is impossible to realize the real-time rheological test of gangue in the on-site goaf. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a device and method for testing the multi-scale rheological properties of gangue filled in goaf, which can realize multi-scale rheological testing of gangue and has a small volume, so it is convenient to deploy on-site in goaf, and finally provide data support for the evaluation of the control effect of filling gangue on the surrounding rock of the mining area.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a multi-scale rheological property testing device for filling gangue in goaf, comprising a water supply pressurization subsystem, a multi-scale gangue rheological testing subsystem, a gas injection lifting subsystem and a gangue displacement monitoring subsystem; The multi-scale gangue rheology test subsystem comprises a gangue pressurized tank, a loading plate, gangue bulk, a flexible sponge ring and a rotating bracket; the gangue pressurized tank is mounted on the rotating bracket through a rotating shaft and can rotate relative to the rotating bracket; the gangue pressurized tank is a cylindrical body with sealing covers at both ends, the loading plate is mounted inside the gangue pressurized tank, and the inside of the gangue pressurized tank is divided into a rheology test cavity and a pressurized water cavity, one end of the sliding rod passes through the upper sealing cover and is connected to the upper surface of the loading plate The rheological test chamber is connected, and the sliding rod is slidably sealed with the upper sealing cover; a ventilation gangue filter is provided at the bottom of the rheological test chamber, the gangue bulk body and the flexible sponge ring are both in the rheological test chamber, and the gangue bulk body is in the center of the flexible sponge ring, and the flexible sponge ring is used to adjust the diameter of the gangue bulk body; an air inlet and an exhaust port are provided at the bottom of the gangue pressurized tank body, and the air inlet and the exhaust port are both connected to the rheological test chamber; a water inlet and a water outlet are provided at the top of the gangue pressurized tank body, and the water inlet and the water outlet are both connected to the pressurized water chamber.

[0006] The water supply and pressurization system comprises a water storage container and a constant pressure and constant flow metering pump; the water storage container is connected to the constant pressure and constant flow metering pump and the water inlet of the gangue pressurization tank body in sequence through a pressurized water pipeline, and the constant pressure and constant flow metering pump injects the water in the water storage container into the pressurized water cavity through the water inlet, thereby pushing the loading plate to move toward the rheological test cavity to pressurize the gangue bulk; the water outlet of the gangue pressurization tank body is connected to the water storage container through a return water pipeline, so as to return the water in the pressurized water cavity to the water storage container; The gas injection and plate lifting subsystem includes a high-pressure gas cylinder and a gas valve. The gas valve is installed at the exhaust port and is used to control the opening and closing of the exhaust port. The high-pressure gas cylinder is connected to the air inlet through a pressurized gas pipeline and is used to inject gas into the rheological test cavity, thereby pushing the loading plate to move toward the pressurized water cavity to increase the height of the rheological test cavity.

[0007] The gangue displacement monitoring subsystem includes a displacement slide bar, a resistive displacement sensor and a data recorder; the resistive displacement sensor is installed at one end of the rotating shaft and can rotate synchronously with the rotating shaft; one end of the displacement slide bar extends into the resistive displacement sensor, and the other end is connected to the other end of the slide bar through a horizontal connecting rod. When the slide bar moves, it can drive the displacement slide bar to move synchronously in the resistive displacement sensor. The resistive displacement sensor detects the displacement amount and feeds it back to the data recorder through the data transmission line.

[0008] Furthermore, the pipeline between the water storage container and the constant pressure and constant flow metering pump is equipped with a first stop valve; the pipeline between the constant pressure and constant flow metering pump and the gangue pressurizing tank is equipped with a second stop valve; the return water pipeline between the gangue pressurizing tank and the water storage container is equipped with a third stop valve. The addition of these stop valves facilitates the control of the on-off of different pipelines.

[0009] Furthermore, the angle α between the horizontal connecting rod and the displacement slide rod satisfies: α-90°≤5°. Setting such an angle range ensures that the horizontal connecting rod can better ensure the synchronization between the displacement slide rod and the sliding rod, thereby improving the detection accuracy of the gangue displacement.

[0010] Furthermore, a universal roller is installed at the lower part of the rotating bracket to facilitate the movement of the equipment; the flexible sponge ring is a high-density sponge with a porosity range of 1-10%; this can meet the requirements for adjusting the diameter of the gangue bulk.

[0011] Furthermore, the upper sealing cover and the lower sealing cover are fixedly connected to the cylindrical body by fastening bolts; this connection method is convenient for disassembly and installation.

[0012] The working method of the multi-scale rheological property testing device for filling gangue in goaf above is as follows: S1. Move the multi-scale gangue rheology testing subsystem to the target gangue filling mining working face, and respectively connect the water supply pressurization subsystem, the gas injection lifting plate subsystem and the gangue displacement monitoring subsystem to the multi-scale gangue rheology testing subsystem.

[0013] S2. Close the exhaust port, and inject gas into the rheological test chamber through the high-pressure gas cylinder through the pressurized gas pipeline and the air inlet. The loading plate moves toward the pressurized water chamber under the action of gas pressure. At this time, the displacement slide moves synchronously, and the resistive displacement sensor records the displacement of the displacement slide in real time and transmits it to the data recorder for recording. When the lifting height of the loading plate reaches the preset test gangue bulk height H, stop the gas injection.

[0014] S3, start the constant pressure and constant flow metering pump to inject the water in the water storage container into the pressurized water cavity at a constant flow rate; when the pressurized water in the pressurized water cavity flows back from the water outlet to the water storage container, it means that the pressurized water cavity is full of water, and at this time, close the water inlet, water outlet and the constant pressure and constant flow metering pump.

[0015] S4. Rotate the gangue pressurizing tank body through the rotating shaft until the lower sealing cover faces upwards, then remove the lower sealing cover; determine the wall thickness M of the flexible sponge ring according to the preset test gangue bulk diameter S and the inner diameter D of the gangue pressurizing tank body, and prepare a flexible sponge ring and place it in the gangue pressurizing tank body; then, fill the sampled gangue from the goaf into the flexible sponge ring, place a ventilation gangue filter, and then install and reset the lower sealing cover.

[0016] S5. Straighten the gangue pressurizing tank again by rotating the axis, then open the water inlet and the exhaust port, and start the constant pressure and constant flow metering pump to inject the water in the water storage container into the pressurized water cavity at a preset loading pressure. The pressurized water in the pressurized water cavity pushes the loading plate to move toward the rheological test cavity to apply pressure to the gangue bulk to cause it to creep and deform. During the pressure displacement of the loading plate, the displacement slide rod moves synchronously under the action of the horizontal connecting rod. At this time, the resistive displacement sensor records the gangue displacement in real time and transmits the gangue displacement to the data recorder for storage.

[0017] S6. When the gangue displacement collected by the data recorder is stable and does not change, close the exhaust port, water inlet and constant pressure and constant flow metering pump, open the water outlet and air inlet, and inject gas into the rheological test chamber through the pressurized gas pipeline through the high-pressure gas cylinder, pushing the loading plate to move toward the pressurized water chamber, and then the water inside it is pressurized and returned to the water storage container from the return pipe to complete water recovery.

[0018] S7. Open the lower sealing cover of the gangue pressurized tank, and take out the gangue bulk and flexible sponge ring after this test to complete this test.

[0019] S8. Repeat steps S2 to S7 for multiple times to complete all tests on different combinations of bulk gangue height H and diameter S, and then complete the multi-scale rheological property test of gangue filled in the goaf.

[0020] Furthermore, the displacement range of the resistive displacement sensor is 0-300 mm, and the acquisition accuracy is 0.01 mm; the minimum height L of the pressurized water cavity is not less than 10 mm; and the constant injection flow range of the constant pressure and constant flow metering pump is 0.01-45 ml / min. Setting these parameters can further ensure the accuracy of the test data.

[0021] Furthermore, in each test, the relationship between the height H and the diameter S of the gangue bulk body satisfies: H=2S; and in each test, the relationship between the diameter S of the gangue bulk body, the inner diameter D of the gangue pressure tank and the wall thickness M of the flexible sponge ring satisfies: D=S+2M.

[0022] Furthermore, the pressure range of the constant pressure and constant flow metering pump during each test is 1~50 MPa.

[0023] Furthermore, the criterion for judging whether the displacement of the gangue in step S6 is stable and unchanged is that the displacement per 100 minutes is less than 0.1 mm / 100 min.

[0024] The current technology uses a servo press to load loose gangue in a cylinder of customized size to achieve gangue rheology testing. Due to the limitations of the press plate, base size and cylinder inner diameter, it is difficult to achieve multi-scale rheology testing of gangue, resulting in blind evaluation of the control effect of filling gangue on the surrounding rock of the mine. The press is large in size, and it is even more impossible to achieve real-time rheology testing of gangue in the goaf during the on-site mining and filling cycle. Compared with the prior art, the present invention adopts a method that includes a water supply and pressurization subsystem, a multi-scale gangue rheology testing subsystem, an air injection and lifting plate subsystem and a gangue displacement monitoring subsystem. A loading plate is set in the gangue pressurization tank of the multi-scale gangue rheology testing subsystem, and the loading plate is used to separate the space into two independent spaces, namely a rheology test cavity and a pressurized water cavity, wherein the rheology test cavity is used to place loose gangue for rheological property testing; the water supply and pressurization subsystem injects pressurized water into the pressurized water cavity to push the loading plate to pressurize the loose gangue. The test is carried out by applying pressure, and the gangue displacement data during the test is recorded by the gangue displacement monitoring subsystem for subsequent analysis; the specific structure of the gangue displacement monitoring subsystem can ensure the accuracy of data acquisition; the whole process does not require a press, which effectively reduces the overall volume of the equipment and facilitates on-site deployment in the goaf; and the height of the rheological test cavity can be adjusted by the gas injection lifting plate subsystem to meet the testing requirements of gangue bulk bodies of different heights, and the diameter of the gangue bulk bodies can be adjusted in conjunction with the flexible sponge ring, ultimately realizing the rheological properties test of gangue bulk bodies of different heights and diameters, providing data support for the evaluation of the control effect of filling gangue on the surrounding rock of the mine. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a radial cross-sectional schematic diagram of the gangue bulk and the flexible sponge ring inside the gangue pressurized tank body of the present invention.

[0026] In the figure: 1-water storage container, 2-1-first stop valve, 2-2-second stop valve, 2-3-third stop valve, 3-pressurized water pipeline, 4-constant pressure and constant flow metering pump, 5-gangue pressurized tank, 6-water inlet, 7-water outlet, 8-fastening bolts, 9-pressurized water cavity, 10-loading pressure plate, 11-gangue bulk, 12-flexible sponge ring, 13-rotating shaft, 14-rotating bracket, 15-ventilation and gangue filter, 16-air inlet, 17-exhaust port, 18-universal roller, 19-high-pressure gas cylinder, 20-pressurized gas pipeline, 21-horizontal connecting rod, 22-displacement slide bar, 23-resistance displacement sensor, 24-data transmission line, 25-data recorder. DETAILED DESCRIPTION

[0027] The present invention will be further described below.

[0028] like Figure 1As shown, a multi-scale rheological property testing device for filling goaf with waste rock includes a water supply and pressurization subsystem, a multi-scale waste rock rheological testing subsystem, a gas injection and plate lifting subsystem, and a waste rock displacement monitoring subsystem; The multi-scale gangue rheology test subsystem includes a gangue pressurized tank body 5, a loading plate 10, a gangue bulk 11, a flexible sponge ring 12 and a rotating bracket 14; the gangue pressurized tank body 5 is mounted on the rotating bracket 14 through a rotating shaft 13, and can rotate relative to the rotating bracket 14; the gangue pressurized tank body 5 is a cylindrical body with sealing covers at both ends, and the loading plate 10 is installed inside the gangue pressurized tank body 5 to divide the inside of the gangue pressurized tank body 5 into a rheology test cavity and a pressurized water cavity 9, one end of the sliding rod passes through the upper sealing cover and is connected to the upper surface of the loading plate 10, and the sliding rod and the upper sealing cover are slidably sealed; a ventilation gangue filter 15 is provided at the bottom of the rheology test cavity, such as Figure 2 As shown, the gangue bulk body 11 and the flexible sponge ring 12 are both in the rheological test chamber, and the gangue bulk body 11 is in the center of the flexible sponge ring 12, and the flexible sponge ring 12 is used to adjust the diameter of the gangue bulk body 11; the flexible sponge ring 12 is a high-density sponge, and its porosity range is 1-10%; the gangue pressurized tank body 5 has an air inlet 16 and an exhaust port 17 at the bottom, and the air inlet 16 and the exhaust port 17 are both connected to the rheological test chamber; the gangue pressurized tank body 5 has a water inlet 6 and a water outlet 7 at the top, and the water inlet 6 and the water outlet 7 are both connected to the pressurized water chamber 9; the rotating bracket 14 is equipped with a universal roller 18 at the bottom to facilitate the movement of the equipment. The upper end sealing cover and the lower end sealing cover are fixedly connected to the cylindrical body by fastening bolts 8.

[0029] The water supply pressurization system includes a water storage container 1 and a constant pressure and constant flow metering pump 4; the water storage container 1 is connected to the constant pressure and constant flow metering pump 4 and the water inlet 6 of the gangue pressurization tank body 5 in sequence through a pressurized water pipeline 3, and the constant pressure and constant flow metering pump 4 injects the water in the water storage container 1 into the pressurized water cavity 9 through the water inlet 6, thereby pushing the loading plate 10 to move toward the rheological test cavity to pressurize the gangue bulk 11; the water outlet of the gangue pressurization tank body 5 is connected to the water storage container 1 through a return water pipeline, which is used to return the water in the pressurized water cavity 9 to the water storage container 1; the pipeline between the water storage container 1 and the constant pressure and constant flow metering pump 4 is equipped with a first stop valve 2-1; the pipeline between the constant pressure and constant flow metering pump 4 and the gangue pressurization tank body 5 is equipped with a second stop valve 2-2; the return water pipeline between the gangue pressurization tank body 5 and the water storage container 1 is equipped with a third stop valve 2-3.

[0030] The gas injection and plate lifting subsystem includes a high-pressure gas cylinder 19 and a gas valve. The gas valve is installed at the exhaust port 17 and is used to control the opening and closing of the exhaust port 17. The high-pressure gas cylinder 19 is connected to the air inlet 16 through a pressurized gas pipeline 20, and is used to inject gas into the rheological test cavity, thereby pushing the loading plate 10 to move toward the pressurized water cavity 9 to increase the height of the rheological test cavity.

[0031] The gangue displacement monitoring subsystem includes a displacement slide bar 22, a resistive displacement sensor 23 and a data recorder 25; the resistive displacement sensor 23 is installed at one end of the rotating shaft 13 and can rotate synchronously with the rotating shaft 13; one end of the displacement slide bar 22 extends into the resistive displacement sensor 23, and the other end is connected to the other end of the sliding bar through a horizontal connecting rod 21. When the sliding bar moves, it can drive the displacement slide bar 22 to move synchronously in the resistive displacement sensor 23. The resistive displacement sensor 23 detects the displacement amount and feeds it back to the data recorder 25 through the data transmission line 24; the angle α between the horizontal connecting rod 21 and the displacement slide bar 22 satisfies: α-90°≤5°.

[0032] The working method of the multi-scale rheological property testing device for filling gangue in goaf above is as follows: S1. Move the multi-scale gangue rheology testing subsystem to the target gangue filling mining working face, and respectively connect the water supply pressurization subsystem, the gas injection lifting plate subsystem and the gangue displacement monitoring subsystem to the multi-scale gangue rheology testing subsystem.

[0033] S2. Close the exhaust port 17, and inject gas into the rheological test chamber through the high-pressure gas cylinder 19 via the pressurized gas pipeline 20 and the air inlet. The loading platen 10 moves toward the pressurized water chamber 9 under the action of the gas pressure. At this time, the displacement slide bar 22 moves synchronously, and the resistive displacement sensor 23 records the displacement of the displacement slide bar 22 in real time and transmits it to the data recorder 25 for recording. When the lifting height of the loading platen 10 reaches the preset test gangue bulk height H, stop the gas injection.

[0034] S3. Start the constant-pressure and constant-current metering pump 4 to inject the water in the water storage container 1 into the pressurized water cavity 9 at a constant flow rate; when the pressurized water in the pressurized water cavity 9 flows back from the water outlet 7 to the water storage container 1, it means that the pressurized water cavity 9 is full of water. At this time, close the water inlet 6, the water outlet 7 and the constant-pressure and constant-current metering pump 4.

[0035] S4. Rotate the gangue pressurizing tank body 5 by the rotating shaft 13 until the lower sealing cover faces upwards, then remove the lower sealing cover; determine the wall thickness M of the flexible sponge ring 12 according to the preset test diameter S of the gangue bulk 11 and the inner diameter D of the gangue pressurizing tank body 5, and prepare the flexible sponge ring 12 and place it in the gangue pressurizing tank body 5; then, fill the sampled gangue from the goaf into the flexible sponge ring 12, place the ventilation and gangue filter 15, and then install and reset the lower sealing cover.

[0036] S5. Straighten the gangue pressurizing tank 5 again by rotating the shaft 13, then open the water inlet 6 and the exhaust port 17, and start the constant pressure and constant flow metering pump 4 to inject the water in the water storage container 1 into the pressurized water cavity 9 at a preset loading pressure. The pressurized water in the pressurized water cavity 9 pushes the loading plate 10 to move toward the rheological test cavity to apply pressure to the gangue bulk 11 to cause it to creep and deform. During the pressure displacement of the loading plate 10, the displacement slide bar 22 is synchronously moved by the horizontal connecting rod 21 (that is, the displacement of the displacement slide bar 22 is equivalent to the displacement of the slide bar, that is, the displacement of the gangue during the test). At this time, the resistive displacement sensor 23 records the displacement of the gangue in real time, and transmits the displacement of the gangue to the data recorder 25 for storage.

[0037] S6. When the gangue displacement collected by the data recorder 25 is stable and does not change, close the exhaust port 17, the water inlet 6 and the constant pressure and constant flow metering pump 4, open the water outlet 7 and the air inlet 16, and inject gas into the rheological test cavity through the high-pressure gas cylinder 19 via the pressurized gas pipeline 20, pushing the loading plate 10 to move toward the pressurized water cavity 9, and then the water inside it is pressurized and returned to the water storage container 1 from the return water pipeline, completing water recovery.

[0038] S7, open the lower sealing cover of the gangue pressurizing tank 5, and take out the gangue bulk 11 and the flexible sponge ring 12 after this test, and complete this test.

[0039] S8. Repeat steps S2 to S7 for multiple times to complete all tests on different combinations of height H and diameter S of the gangue bulk body 11, and then complete the multi-scale rheological property test of the gangue filled in the goaf.

[0040] As an improvement of the working method of the present invention, the displacement range of the resistive displacement sensor 23 is 0~300mm, and the acquisition accuracy is 0.01mm; the minimum height L of the pressurized water cavity 9 is not less than 10mm; the constant injection flow range of the constant pressure and constant current metering pump 4 is 0.01~45ml / min; the height H and diameter S of the gangue bulk body 11 in each test satisfy: H=2S; and the diameter S of the gangue bulk body 11, the inner diameter D of the gangue pressurized tank body 5 and the wall thickness M of the flexible sponge ring 12 satisfy: D=S+2M in each test; the pressurization range of the constant pressure and constant current metering pump 4 in each test is 1~50Mpa; the judgment standard for the gangue displacement in step S6 to be stable and unchanged is that the displacement per 100 minutes is less than 0.1mm / 100min. Setting these parameters can further ensure the accuracy of the data obtained by the test method of the present invention.

[0041] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A multi-scale rheological property testing device for goaf filling waste rock, characterized in that: It includes water supply and pressurization subsystem, multi-scale gangue rheology test subsystem, gas injection and lifting subsystem and gangue displacement monitoring subsystem; The multi-scale gangue rheology test subsystem comprises a gangue pressurized tank, a loading plate, gangue bulk, a flexible sponge ring and a rotating bracket; the gangue pressurized tank is mounted on the rotating bracket through a rotating shaft and can rotate relative to the rotating bracket; the gangue pressurized tank is a cylindrical body with sealing covers at both ends, the loading plate is mounted inside the gangue pressurized tank, and the inside of the gangue pressurized tank is divided into a rheology test cavity and a pressurized water cavity, one end of the sliding rod passes through the upper sealing cover and is connected to the upper surface of the loading plate The sliding rod is connected to the upper sealing cover for sliding sealing; a ventilation gangue filter is provided at the bottom of the rheological test cavity, the gangue bulk body and the flexible sponge ring are both in the rheological test cavity, and the gangue bulk body is in the center of the flexible sponge ring, and the flexible sponge ring is used to adjust the diameter of the gangue bulk body; an air inlet and an exhaust port are provided at the bottom of the gangue pressurized tank body, and the air inlet and the exhaust port are both connected to the rheological test cavity; a water inlet and a water outlet are provided at the top of the gangue pressurized tank body, and the water inlet and the water outlet are both connected to the pressurized water cavity; The water supply and pressurization system comprises a water storage container and a constant pressure and constant flow metering pump; the water storage container is connected to the constant pressure and constant flow metering pump and the water inlet of the gangue pressurization tank body in sequence through a pressurized water pipeline, and the constant pressure and constant flow metering pump injects the water in the water storage container into the pressurized water cavity through the water inlet, thereby pushing the loading plate to move toward the rheological test cavity to pressurize the gangue bulk; the water outlet of the gangue pressurization tank body is connected to the water storage container through a return water pipeline, so as to return the water in the pressurized water cavity to the water storage container; The gas injection and plate lifting subsystem includes a high-pressure gas cylinder and a gas valve. The gas valve is installed at the exhaust port and is used to control the opening and closing of the exhaust port. The high-pressure gas cylinder is connected to the air inlet through a pressurized gas pipeline and is used to inject gas into the rheological test cavity, thereby pushing the loading plate to move toward the pressurized water cavity to increase the height of the rheological test cavity. The gangue displacement monitoring subsystem includes a displacement slide bar, a resistive displacement sensor and a data recorder; the resistive displacement sensor is installed at one end of the rotating shaft and can rotate synchronously with the rotating shaft; one end of the displacement slide bar extends into the resistive displacement sensor, and the other end is connected to the other end of the slide bar through a horizontal connecting rod. When the slide bar moves, it can drive the displacement slide bar to move synchronously in the resistive displacement sensor. The resistive displacement sensor detects the displacement amount and feeds it back to the data recorder through the data transmission line.

2. The multi-scale rheological property testing device for goaf filling waste rock according to claim 1, characterized in that: The pipeline between the water storage container and the constant pressure and constant flow metering pump is equipped with a first stop valve; the pipeline between the constant pressure and constant flow metering pump and the gangue pressurizing tank is equipped with a second stop valve; the return water pipeline between the gangue pressurizing tank and the water storage container is equipped with a third stop valve.

3. The multi-scale rheological property testing device for goaf filling waste rock according to claim 1, characterized in that: The angle α between the horizontal connecting rod and the displacement sliding rod satisfies: α-90°≤5°.

4. The multi-scale rheological property testing device for goaf filling waste rock according to claim 1, characterized in that: The lower part of the rotating bracket is equipped with a universal roller; the flexible sponge ring is a high-density sponge with a porosity range of 1-10%.

5. The multi-scale rheological property testing device for goaf filling waste rock according to claim 1, characterized in that: The upper sealing cover and the lower sealing cover are fixedly connected to the cylindrical body by fastening bolts.

6. A working method of the multi-scale rheological properties testing device for goaf filling waste rock according to claim 1, characterized in that: The specific steps are: S1. Move the multi-scale gangue rheology test subsystem to the target gangue filling mining working face, and respectively connect the water supply pressurization subsystem, the gas injection plate lifting subsystem and the gangue displacement monitoring subsystem to the multi-scale gangue rheology test subsystem; S2, close the exhaust port, and inject gas into the rheological test chamber through the high-pressure gas cylinder through the pressurized gas pipeline and the air inlet. The loading plate moves toward the pressurized water chamber under the action of the gas pressure. At this time, the displacement slide moves synchronously, and the resistive displacement sensor records the displacement of the displacement slide in real time and transmits it to the data recorder for recording. When the lifting height of the loading plate reaches the preset test gangue bulk height H, stop the gas injection; S3, start the constant pressure and constant flow metering pump to inject the water in the water storage container into the pressurized water cavity at a constant flow rate; when the pressurized water in the pressurized water cavity flows back from the water outlet to the water storage container, it means that the pressurized water cavity is full of water, and at this time, close the water inlet, the water outlet and the constant pressure and constant flow metering pump; S4, rotating the gangue pressurizing tank body through the rotating shaft until the lower end sealing cover faces upward, then removing the lower end sealing cover; determining the wall thickness M of the flexible sponge ring according to the preset test gangue bulk diameter S and the inner diameter D of the gangue pressurizing tank body, and preparing a flexible sponge ring and placing it in the gangue pressurizing tank body; then, filling the goaf sampled gangue inside the flexible sponge ring, placing a ventilation gangue filter, and then installing and resetting the lower end sealing cover; S5. Straighten the gangue pressurizing tank again by rotating the axis, then open the water inlet and the exhaust port, and start the constant pressure and constant flow metering pump to inject the water in the water storage container into the pressurized water cavity at a preset loading pressure. The pressurized water in the pressurized water cavity pushes the loading plate to move toward the rheological test cavity to pressurize the gangue bulk to cause it to creep and deform. During the pressure displacement process of the loading plate, the displacement slide bar moves synchronously under the action of the horizontal connecting rod. At this time, the resistive displacement sensor records the gangue displacement in real time and transmits the gangue displacement to the data recorder for storage. S6. When the gangue displacement collected by the data recorder is stable and does not change, close the exhaust port, water inlet and constant pressure and constant flow metering pump, open the water outlet and air inlet, and inject gas into the rheological test cavity through the pressurized gas pipeline through the high-pressure gas cylinder, push the loading plate to move toward the pressurized water cavity, and then the water inside is pressurized and returned to the water storage container from the return water pipeline to complete the water recovery; S7, open the lower sealing cover of the gangue pressurized tank, and take out the gangue bulk and the flexible sponge ring after this test, and complete this test; S8. Repeat steps S2 to S7 for multiple times to complete all tests on different combinations of bulk gangue height H and diameter S, and then complete the multi-scale rheological property test of gangue filled in the goaf.

7. The working method according to claim 6, characterized in that: The displacement range of the resistive displacement sensor is 0-300 mm, and the acquisition accuracy is 0.01 mm; the minimum height L of the pressurized water cavity is not less than 10 mm; the constant injection flow range of the constant pressure and constant flow metering pump is 0.01-45 ml / min.

8. The working method according to claim 6, characterized in that: The relationship between the height H and diameter S of the gangue bulk in each test is: H=2S; and the relationship between the diameter S of the gangue bulk, the inner diameter D of the gangue pressure tank and the wall thickness M of the flexible sponge ring in each test is: D=S+2M.

9. The working method according to claim 6, characterized in that: The pressure range of the constant pressure and constant flow metering pump during each test is 1~50 MPa.

10. The working method according to claim 6, characterized in that: The criterion for judging whether the displacement of the gangue in step S6 is stable and unchanged is that the displacement per 100 minutes is less than 0.1 mm / 100 min.

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