Three-dimensional similarity test device and test method for mining inclined coal seams with adjustable inclination angle of confined aquifer

Abstract

The invention discloses a three-dimensional similarity test device and a test method for inclined coal seam mining with adjustable inclination angle of a confined aquifer, and relates to the field of similarity test of inclined coal seam mining on confined water. The device comprises a test support, an internal frame, a model storage cavity, a loading plate, a horizontal loading system, a vertical loading system, a water pressure loading system, an inclination adjustment system, a signal acquisition and processing system, a three-dimensional test model, and a coal seam mining simulation system. The test device realizes the adjustable inclination angle of the confined aquifer, the gradient distribution of the water pressure load of the aquifer, and the authenticity of the vertical and horizontal stress states of the inclined coal seam, and realizes the segmented and step-by-step excavation simulation of the coal seam in the closed space of the three-dimensional similarity model. The test device can truly invert the generation, expansion, and penetration of rock strata cracks in the bottom plate of the confined water mining, and finally form a dynamic evolution process of a water guide channel, and can better carry out the prediction research of water inrush from the bottom plate of longwall mining of inclined coal seams with different inclination angles on confined water.

Description

Technical Field

[0001] The invention relates to a similarity test simulation device for coal seam mining, in particular to a three-dimensional similarity test device and a test method for inclined coal seam mining with adjustable inclination angle of a pressure-bearing aquifer. Background Art

[0002] With the increase in coal mining depth and mining intensity, the water pressure and ground pressure on the floor of the mining face are getting greater and greater, and the geological structure environment is becoming more and more complex, making the problem of water inrush from the floor more serious.

[0003] The occurrence conditions of coal seams in my country are diverse. In addition to horizontal and near-horizontal coal seams, there are also a large number of inclined coal seams. The stress state of the surrounding rock in the inclined coal seam mining area has obvious asymmetric characteristics. The water pressure of the underlying confined aquifer is no longer a uniformly distributed water pressure, but has a certain water pressure gradient along the inclination direction of the coal seam. The stress distribution, failure and instability characteristics, water inrush evolution law and water inrush danger area of ​​the floor rock strata during the mining of inclined coal seams above confined water are completely different from those of near-horizontal coal seams. If the research results of horizontal and near-horizontal coal seams are used to predict the floor water inrush problem of inclined coal seams, it will inevitably cause safety hazards in the pressurized mining of inclined coal seams above confined water. Therefore, it is necessary to conduct a systematic study on the destruction characteristics of the floor rock strata of inclined coal seams, their water barrier properties and water inrush prediction, in order to achieve safe pressurized mining of inclined coal seams above confined water.

[0004] Similarity tests have the advantages of strong intuitiveness, good flexibility, high efficiency, and good repeatability. Physical similarity simulation of the water inrush process of the floor of the inclined coal seam above confined water can intuitively and vividly reproduce the dynamic evolution process of the generation, expansion, and penetration of rock strata cracks in the floor of the confined water mining, and finally form a water channel. However, the existing test models for the simulation of inclined coal seams are either two-dimensional simulations, which cannot truly simulate the stress state and longwall mining process of the inclined coal seams; or they cannot simulate the stress state and longwall mining process of the inclined coal seams above confined water, and cannot simulate the evolution of floor water inrush during the mining process of the inclined coal seams.

[0005] In addition, for the three-dimensional similarity simulation test device, simulating the excavation process of the coal seam in a confined space is also a difficulty and key to achieving three-dimensional similarity simulation. In the prior art, the mining of the coal seam is simulated by mining a coal seam in one go or by using a steel plate or a wooden board. These methods are only two-dimensional mining simulation methods, which can be considered as simulating the step-by-step excavation of the coal seam at most, but cannot simulate the segmented excavation of the coal seam. This is inconsistent with the mining process of the coal seam in actual engineering. Similarly, Wang Hongwei et al. (Large-scale three-dimensional loadable similarity simulation test of high-angle coal seam mining [J]. Journal of China Coal Society, 2015, 40(7): 1505-1511) achieved similar simulation of high-angle coal seam excavation in a three-dimensional confined space by injecting water to dissolve and discharge the cemented soluble blocks filled in the capsule. However, the bearing capacity of the cemented soluble blocks filled in the capsule is small and cannot be quantitatively controlled, let alone simulate the original stress state of the coal seam. At the same time, since the capsule simulating the excavation of the coal seam is in the shape of a long strip and runs through the entire working face, it is even more impossible to simulate the segmented excavation process of the coal seam.

[0006] In summary, the existing two-dimensional and three-dimensional similar test devices and methods for simulating coal seam excavation cannot truly invert the dynamic evolution process of the generation, expansion, and connection of the rock strata cracks in the bottom plate of the inclined coal seam mining on confined water, and finally form a water channel. Therefore, it is urgent to develop a three-dimensional similar test device and test method for the mining of inclined coal seams on confined water, and systematically carry out research on the damage characteristics of the rock strata in the bottom plate of the inclined coal seam, its water barrier performance, and water inrush prediction. At the same time, in order to ensure the wide application of the test device and the effectiveness of the simulation, it is necessary to realize the adjustable inclination of the confined aquifer and the authenticity of the stress state of the inclined coal seam, so as to facilitate the three-dimensional similar simulation test of the longwall mining of the inclined coal seam with different inclination angles on confined water, predict the water inrush of the bottom plate of the inclined coal seam, and realize the safe pressure mining of the inclined coal seam on confined water. Summary of the invention

[0007] In order to solve the above problems, the purpose of the present invention is to provide a three-dimensional similarity test device and test method for inclined coal seam mining with adjustable inclination angle of a confined aquifer.

[0008] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0009] A three-dimensional similarity test device for inclined coal seam mining with adjustable inclination angle of a confined aquifer, comprising a test support, an internal frame, a model storage cavity, a loading plate, a horizontal loading system, a vertical loading system, a water pressure loading system, a signal acquisition and processing system, and a three-dimensional test model, wherein the internal frame is arranged inside the test support, the model storage cavity is located inside the internal frame, the loading plate is located inside the model storage cavity, the three-dimensional test model is stored in the model storage cavity, the horizontal loading system and the vertical loading system apply horizontal pressure and vertical pressure to the three-dimensional test model through the loading plate, the water pressure loading system applies water pressure to the three-dimensional test model from the bottom, the signal acquisition and processing system is used to collect and process data signals during the test, and the three-dimensional model includes a coal seam floor, a mining coal seam, and a coal seam roof from bottom to top; and also includes an inclination adjustment system and a coal seam mining simulation system;

[0010] The inclination adjustment system is used to adjust the inclination of the model storage chamber, and the inclination adjustment system includes a track, a pulley matched with the track, a hydraulic jack, a hydraulic oil pipe, a hydraulic pressure stabilizing device, a hydraulic valve and a hydraulic control device. The track is fixedly arranged on the test bracket, the pulley can slide on the track, and the pulley is fixedly installed at one end of the bottom of the model storage chamber, the hydraulic jack is rotatably connected to the other end of the bottom of the model storage chamber, one end of the hydraulic oil pipe is connected to the hydraulic jack, and the other end of the hydraulic oil pipe is connected to the hydraulic control device, and the hydraulic pressure stabilizing device and the hydraulic valve are sequentially arranged between the hydraulic jack and the hydraulic control device on the hydraulic oil pipe;

[0011] The coal seam mining simulation system includes an inflatable structure and an inflatable bag connected to the inflatable structure. The inflatable bags are connected in series in an S shape and are closely arranged in sequence and embedded in the mining coal seam. The tail ends of the inflatable bags are connected to deflation pipes, and adjacent inflatable bags are connected by the deflation pipes. The deflation pipes are provided with deflation valves, and the gas in the inflatable bags is discharged to the outside of the model storage cavity through the deflation pipes.

[0012] As a preferred embodiment of the three-dimensional similarity test device for inclined coal seam mining with adjustable inclination of a pressurized aquifer of the present invention, the inclination adjustment system also includes an inclination rotary head and an adjustment plate. The top of the hydraulic jack is connected to the adjustment plate through the inclination rotary head, and the adjustment plate is connected to the bottom of the model storage cavity. The adjustment plate applies a supporting load to the model storage cavity with different inclination angles through the inclination rotary head.

[0013] As another preferred embodiment of the three-dimensional similarity test device for inclined coal seam mining with adjustable inclination of a confined aquifer of the present invention, the inclination adjustment system also includes an inclination scale, which is arranged on the hydraulic jack and is used to display the inclination angle of the model storage cavity.

[0014] As another preferred embodiment of the three-dimensional similarity test device for inclined coal seam mining with adjustable inclination of a confined aquifer of the present invention, the loading plate includes a top loading plate and a side loading plate. The top loading plate applies vertical pressure to the three-dimensional test model under the action of the vertical loading system, and the side loading plate applies horizontal pressure to the three-dimensional test model under the action of the horizontal loading system. The model storage cavity is in the shape of a rectangular parallelepiped, and the top loading plate and the side loading plate can adjust their angles as the model storage cavity is tilted, so that the top loading plate is always parallel to the bottom surface of the model storage cavity, and at the same time, the side loading plate is always parallel to the side of the model storage cavity.

[0015] As another preferred embodiment of the three-dimensional similarity test device for inclined coal seam mining with adjustable inclination of a confined aquifer of the present invention, the air-filled bag includes a starting air-filled bag, a middle air-filled bag, and a terminal air-filled bag according to their positions, and the air-filled structure is connected to the starting air-filled bag, and the middle air-filled bag and the terminal air-filled bag are inflated through the starting air-filled bag, and all the air-filled bags are deflated through the deflation pipes connected to the air-filled bags.

[0016] As another preferred embodiment of the three-dimensional similarity test device for mining inclined coal seams with adjustable inclination of a pressurized aquifers of the present invention, the inflation structure includes an inflation tube, an inflation pressure stabilizing device, an inflation valve, and an inflation control device arranged on the inflation tube, the inflation tube passes through the model storage cavity and is connected with the starting inflation bag, and the inflation pressure stabilizing device, the inflation valve, and the inflation control device are located outside the model storage cavity.

[0017] As another preferred embodiment of the three-dimensional similarity test device for mining inclined coal seams with adjustable inclination of a pressurized aquifer of the present invention, the vent pipe is a U-shaped pipe, the U-shaped pipe is connected to the bottom corner of the side of the inflatable bag, and the vent valve on the U-shaped pipe passes through the mined coal seam and is left outside the model storage cavity.

[0018] As another preferred embodiment of the three-dimensional similarity test device for mining inclined coal seams with adjustable inclination angle of a confined aquifer of the present invention, the inflatable bag is a rectangular parallelepiped capsule.

[0019] The present invention also provides a three-dimensional similarity test method for mining inclined coal seams with adjustable inclination angle of a pressure-bearing aquifer using the above device, comprising the following steps:

[0020] (1) Material configuration: According to the hydrogeological conditions of the inclined coal seam working face above the pressurized water to be simulated and the physical and mechanical properties of the coal seam and its roof and floor strata, the proportion of similar simulation materials for the coal seam floor, mined coal seam and coal seam roof is determined, so as to determine the amount of various raw materials required for each rock layer; according to the properties of the components of similar simulation materials for the coal seam floor, mined coal seam and coal seam roof, the required materials for each rock layer are weighed strictly in proportion, and the fluid-solid coupling similar simulation materials are prepared and loaded into the corresponding containers, waiting for the model to be laid;

[0021] (2) Model preparation: The model storage cavity is adjusted to a horizontal state through the inclination adjustment system, and the evenly mixed coal seam floor similar simulation material is laid on the bottom of the model storage cavity, and the mined coal seam and coal seam roof similar simulation materials are laid thereon in sequence, and a certain amount of mica powder is spread between each rock layer; at the same time, during the model laying process, the signal acquisition end of the signal acquisition and processing system is buried at the predetermined monitoring position of the coal seam floor; according to the simulated mining size and mining height of the inclined coal seam working face, a space with the same mining size and mining height as the inclined coal seam working face is cut out in the mined coal seam, and Replaced with the inflatable bag in the coal seam mining simulation system, the size and number of the inflatable bag are determined by the mining parameters of the inclined coal seam working face; the inflatable bags are connected in series in an S shape and closely arranged in the excavation space of the mined coal seam, and filled with pressurized gas with the same strength as the mined coal seam; during the model laying process, the transmission wire at the signal acquisition end, the inflation valve on the inflation pipe and the deflation valve on the U-shaped tube are all led out from the sealed threading holes on the transparent glass plates at the front and back of the model storage cavity to ensure the sealing of the model storage cavity; the coal seam bottom plate, the mined coal seam and the coal seam roof are compacted and fixed to prepare a three-dimensional fluid-solid coupling similarity simulation test model;

[0022] (3) Model loading: After the 3D test model to be laid is dry, first, the model storage cavity is adjusted to the angle of the inclined coal seam to be simulated by raising the hydraulic jack using the inclination adjustment system; secondly, a vertical load of a certain gradient is applied to the top of the 3D test model through the top loading plate using the vertical loading system; thirdly, a horizontal load that increases linearly with the burial depth is applied to the left and right sides of the 3D test model through the side loading plates using the horizontal loading system; finally, a water pressure load of a certain gradient is applied to the bottom of the 3D test model using the water pressure loading system, and the water pressure load applied to the 3D test model during similar tests is always less than the horizontal load applied;

[0023] (4) Model excavation: After the load on the three-dimensional test model is balanced, close all the deflation valves and inflation valves in the coal seam mining simulation system; first, open the deflation valve on the U-shaped tube connected to the end inflation bag, deflate the end inflation bag, and realize the first step of segmented excavation simulation of coal seam mining; second, open the deflation valve on the U-shaped tube between the end inflation bag and the middle inflation bag directly connected to it, deflate the middle inflation bag, and realize the second step of segmented excavation simulation of coal seam mining; third, open the deflation valves on the U-shaped tubes between the remaining middle inflation bags in turn, deflate the remaining middle inflation bags in turn, and realize the step-by-step excavation simulation of coal seam mining; finally, open the deflation valve on the U-shaped tube between the middle inflation bags directly connected to the start inflation bag, deflate the start inflation bag, and realize the entire excavation simulation of coal seam mining;

[0024] (5) Data acquisition: During the simulation of the segmented and step-by-step excavation of the inclined coal seam working face above confined water, the multi-field precursor information such as stress, displacement, crack, seepage, temperature, etc. of the bottom strata and the evolution law of the apparent resistivity signal of the bottom strata are collected synchronously during the advancement of the inclined coal seam working face. Through the collection and analysis of the multi-field precursor information and apparent resistivity signal, the evolution law and coupling characteristics of the multi-field precursor information such as stress, displacement, crack, seepage, temperature, apparent resistivity, etc. of the bottom strata during the water inrush from the bottom of the inclined coal seam above confined water are studied;

[0025] (6) Influencing factors: The hydrogeological conditions and boundary conditions of the three-dimensional experimental model of inclined coal seam mining above confined water were changed, and the above experimental steps were repeated to study the influence of mining depth, coal seam inclination, lithology and thickness of the impermeable layer, water pressure of the aquifer, horizontal stress, and working face advancement distance on the multi-field precursor information of the floor rock layer stress, displacement, cracks, seepage, temperature, and apparent resistivity during the process of water inrush from the floor of the inclined coal seam above confined water, as well as its evolution law and coupling characteristics.

[0026] Preferably, during the (4) model excavation process, the speed of excavation of the simulated coal seam can be achieved by controlling the air release speed and interval time of the air release valve.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] The present invention provides a three-dimensional similarity test device and a test method for mining an inclined coal seam with an adjustable inclination angle in a confined aquifer. The test device and the test method can truly invert the dynamic evolution process of the generation, expansion, and penetration of cracks in the bottom rock layer of the longwall mining of the inclined coal seam above the confined water, and finally form a water-conducting channel; the coal seam mining simulation system of the test device can realize the controllable excavation of the three-dimensional similarity model in a confined space, and can truly simulate the step-by-step excavation of the coal seam, especially the segmented excavation of the coal seam, which is consistent with the actual coal seam mining process.

[0029] The test device realizes the adjustable inclination of the confined aquifer, the gradient distribution of the water pressure load of the inclined aquifer, and the authenticity of the gradient stress state in the vertical and horizontal directions of the inclined coal seam; in addition, the similar test model of the test device can be laid in a horizontal state, which ensures the wide application of the test device, the effectiveness of the simulation and the ease of operation, and can better carry out three-dimensional similarity simulation tests of longwall mining of inclined coal seams with different inclination angles above confined water, and predict water inrush from the bottom of inclined coal seams with different inclination angles. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings;

[0031] Figure 1 It is a cross-sectional schematic diagram of a three-dimensional similarity test device for mining an inclined coal seam with adjustable inclination angle of a confined aquifer;

[0032] Figure 2 A top view schematic diagram of a three-dimensional similarity test device for mining an inclined coal seam with adjustable inclination angle of a confined aquifer;

[0033] Figure 3 A schematic side view of a three-dimensional similarity test device for mining an inclined coal seam with adjustable inclination angle of a confined aquifer;

[0034] Figure 4 It is a top view schematic diagram of the water-permeable steel grate on the upper part of the concave water tank;

[0035] Figure 5 It is a cross-sectional schematic diagram of the three-dimensional test model and the signal acquisition and processing system;

[0036] Figure 6 This is a three-dimensional schematic diagram of the coal mining simulation system.

[0037] The main component symbols are described as follows:

[0038] 1. Test support, 1-1, support base, 1-2, outer vertical beam, 1-3, outer top beam;

[0039] 2. Internal frame, 2-1, inner vertical beam, 2-2, inner top beam;

[0040] 3. Model storage cavity, 3-1. Concave cavity, 3-2. Concave water tank, 3-3. Transparent glass plate, 3-4. Permeable steel grate;

[0041] 4. Loading plate, 4-1. Side loading plate, 4-2. Top loading plate;

[0042] 5. Horizontal loading system, 5-1. Horizontal loading device, 5-1a. Horizontal hydraulic cylinder, 5-1b. Horizontal piston rod, 5-1c. Horizontal swivel, 5-1d. Horizontal pad, 5-2. Horizontal hydraulic oil pipe, 5-3. Horizontal tee, 5-4. Horizontal pressure stabilizing device, 5-5. Horizontal hydraulic valve, 5-6. Horizontal hydraulic control device;

[0043] 6. Vertical loading system, 6-1. Vertical loading device, 6-2. Vertical hydraulic oil pipe, 6-3. Vertical tee, 6-4. Vertical pressure stabilizing device, 6-5. Vertical hydraulic valve, 6-6. Vertical hydraulic control device;

[0044] 7. Water pressure loading system, 7-1. High-pressure water pipe, 7-2. Water pressure stabilizing device, 7-3. Water injection valve, 7-4. Water pressure control device, 7-5. Water tank, 7-6. Water pressure tee, 7-7. Drain or exhaust valve;

[0045] 8. Inclination adjustment system, 8-1. Track, 8-2. Pulley, 8-3. Hydraulic jack, 8-4. Inclination swivel, 8-5. Adjustment plate, 8-6. Inclination scale, 8-7. Hydraulic oil pipe, 8-8. Hydraulic pressure stabilizing device, 8-9. Hydraulic valve, 8-10. Hydraulic control device;

[0046] 9. Signal acquisition and processing system, 9-1. Multi-field precursor information acquisition and processing system, 9-1a. Optical fiber sensor array, 9-1a1. Optical fiber stress sensor, 9-1a2. Optical fiber displacement sensor, 9-1a3. Optical fiber acoustic emission sensor, 9-1a4. Optical fiber seepage pressure sensor, 9-1a5. Optical fiber temperature sensor, 9-1b. Optical fiber splitter, 9-1c. Grating demodulation device, 9-1d. PC for multi-field precursor information acquisition and processing, 9-1e. Optical fiber cable, 9-2. Apparent resistivity signal acquisition and processing system, 9-2a. Network parallel circuit copper sheet electrode, 9-2b. WBD type network parallel electrical instrument, 9-2c. PC for Surfer software assisted drawing, 9-2d. Copper enameled signal transmission wire;

[0047] 10. Three-dimensional test model, 10-1. Coal seam floor, 10-2. Mined coal seam, 10-3. Coal seam roof;

[0048] 11. Coal seam mining simulation system, 11-1. Inflatable bag, 11-1a. Starting inflatable bag, 11-1b. Middle inflatable bag, 11-1c. End inflatable bag, 11-2. Inflatable tube, 11-3. U-shaped tube, 11-4. Release valve, 11-5. Inflatable pressure stabilizing device, 11-6. Inflatable valve, 11-7. Inflatable control device, 11-8. Inflatable structure. DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0050] like Figure 1-4 As shown, a three-dimensional similarity test device for inclined coal seam mining with adjustable inclination of a confined aquifer includes a test bracket 1, an internal frame 2, a model storage chamber 3, a loading plate 4, a horizontal loading system 5, a vertical loading system 6, a water pressure loading system 7, an inclination adjustment system 8, a signal acquisition and processing system 9, a three-dimensional test model 10 and a coal seam mining simulation system 11.

[0051] The test support 1 includes a support base 1-1, an outer vertical beam 1-2 and an outer top beam 1-3. The outer vertical beams 1-2 are connected to both sides of the support base 1-1, and the outer top beam 1-3 is connected to the top of the outer vertical beam 1-2. The internal frame 2 includes an inner vertical beam 2-1 and an inner top beam 2-2. The inner vertical beam 2-1 is connected to the support base 1-1, and the inner top beam 2-2 is connected to the top of the inner vertical beam 2-1. The internal frame 2 is located inside the test support 1.

[0052] The model storage cavity 3 is a rectangular parallelepiped, specifically including a concave cavity 3-1, a concave water trough 3-2, a transparent glass plate 3-3 and a permeable steel grate 3-4. The concave water trough 3-2 is arranged at the lower part of the concave cavity 3-1, the front and rear parts of the concave cavity 3-1 are connected with a transparent glass plate 3-3, the upper part of the concave water trough 3-2 is connected with a permeable steel grate 3-4, and the permeable steel grate 3-4 is a rectangular steel plate with circular through holes evenly arranged thereon.

[0053] The loading plate 4 includes a side loading plate 4-1 and a top loading plate 4-2, and the loading plate 4 is located inside the model storage cavity 3. In order to ensure that the vertical load and the horizontal load can effectively act on the three-dimensional test model 10, the top loading plate 4-2 and the side loading plate 4-1 can adjust the angles as the model storage cavity 3 tilts, so that the top loading plate 4-2 is always parallel to the bottom surface of the model storage cavity 3, and the side loading plate 4-1 is always parallel to the side surface of the model storage cavity 3.

[0054] The horizontal loading system 5 applies a horizontal load to the three-dimensional test model 10 placed in the model storage chamber 3 through the side loading plate 4-1. Specifically, the horizontal loading system 5 includes a horizontal loading device 5-1, a horizontal hydraulic oil pipe 5-2, a horizontal tee 5-3, a horizontal pressure stabilizing device 5-4, a horizontal hydraulic valve 5-5 and a horizontal hydraulic control device 5-6; the outer vertical beams 1-2 on both sides of the support base 1-1 are connected with three horizontal loading devices 5-1 in sequence from top to bottom, the horizontal loading device 5-1 passes through the inner vertical beam 2-1 and the model storage chamber 3 and is rotatably connected to the side loading plate 4-1, the horizontal loading device 5-1 passes through the outer vertical beam 1-2 and is connected to the horizontal hydraulic oil pipe 5-2, the other end of the horizontal hydraulic oil pipe 5-2 is connected to the horizontal hydraulic control device 5-6, and the horizontal hydraulic oil pipe 5-2 is connected with a horizontal tee 5-3, a horizontal pressure stabilizing device 5-4 and a horizontal hydraulic valve 5-5 in sequence from the horizontal loading device 5-1 to the horizontal hydraulic control device 5-6. The horizontal loading device 5-1 includes a horizontal hydraulic cylinder 5-1a, a horizontal piston rod 5-1b, a horizontal swivel head 5-1c and a horizontal pad 5-1d; the outer vertical beam 1-2 is connected to the horizontal hydraulic cylinder 5-1a, the horizontal hydraulic cylinder 5-1a is connected to the horizontal hydraulic oil pipe 5-2 and the horizontal piston rod 5-1b, the horizontal piston rod 5-1b passes through the inner vertical beam 2-1 and the model storage chamber 3 and is connected to the horizontal swivel head 5-1c and the horizontal pad 5-1d in turn, and the horizontal pad 5-1d is connected to the side loading plate 4-1. In order to facilitate the application of horizontal load to the three-dimensional test model after the inclination angle is adjusted, the horizontal loading device 5-1 on the outer vertical beam 1-2 can be adjusted and moved up and down synchronously along the outer vertical beam 1-2 according to the inclination degree of the model storage cavity 3, the horizontal piston rod 5-1b can be extended or shortened accordingly according to the inclination degree of the model storage cavity 3, and the horizontal pad 5-1d and the side loading plate 4-1 can be tilted synchronously according to the inclination degree of the model storage cavity 3 through the horizontal turntable 5-1c; the horizontal loading system 5 can apply a certain gradient of horizontal load to the left and right sides of the three-dimensional test model 10 in the model storage cavity 3 with different inclination angles through the side loading plate 4-1.

[0055] The vertical loading system 6 applies a vertical load to the three-dimensional test model 10 placed in the model storage chamber 3 from the top through the top loading plate 4-2. The vertical loading system 6 includes a vertical loading device 6-1, a vertical hydraulic oil pipe 6-2, a vertical three-way 6-3, a vertical pressure stabilizing device 6-4, a vertical hydraulic valve 6-5 and a vertical hydraulic control device 6-6; the outer top beam 1-3 is sequentially connected with three vertical loading devices 6-1 from left to right, the vertical loading device 6-1 passes through the inner top beam 2-2 and the model storage chamber 3 and is rotatably connected with the top loading plate 4-2 and the vertical hydraulic oil pipe 6-2, the vertical hydraulic oil pipe 6-2 is connected with the vertical hydraulic control device 6-6, and the vertical hydraulic oil pipe 6-2 is sequentially connected with a vertical three-way 6-3, a vertical pressure stabilizing device 6-4 and a vertical hydraulic valve 6-5 in the direction from the vertical loading device 6-1 to the vertical hydraulic control device 6-6. The vertical loading device 6-1 includes a vertical hydraulic cylinder 6-1a, a vertical piston rod 6-1b, a vertical swivel head 6-1c and a vertical pad 6-1d; the outer top beam 1-3 is connected to the vertical hydraulic cylinder 6-1a, the vertical hydraulic cylinder 6-1a is connected to the vertical hydraulic oil pipe 6-2 and the vertical piston rod 6-1b, the vertical piston rod 6-1b passes through the inner top beam 2-2 and the model storage chamber 3 and is connected to the vertical swivel head 6-1c and the vertical pad 6-1d, and the vertical pad 6-1d is connected to the top loading plate 4-2. The vertical loading device 6-1 on the outer top beam 1-3 can be adjusted and moved synchronously left and right along the outer top beam 1-3 according to the inclination of the model storage chamber 3, the vertical piston rod 6-1b can be extended or shortened accordingly according to the inclination of the model storage chamber 3, and the vertical pad 6-1d and the top loading plate 4-2 can be tilted synchronously according to the inclination of the model storage chamber 3 through the vertical rotating head 6-1c; the vertical loading system 6 can apply a certain gradient of vertical load to the top of the three-dimensional test model 10 in the model storage chamber 3 with different inclination angles through the top loading plate 4-2. The horizontal loading system 5 and the vertical loading system 6 apply horizontal and vertical loads to the three-dimensional test model 10 placed in the model storage chamber 3 from the side and top respectively through the side loading plate 4-1 and the top loading plate 4-2.

[0056] The water pressure loading system 7 includes a high-pressure water pipe 7-1, a water pressure stabilizing device 7-2, a water injection valve 7-3, a water pressure control device 7-4, a water tank 7-5, a water pressure tee 7-6 and a drain or exhaust valve 7-7; the high-pressure water pipe 7-1 is connected to the concave water tank 3-2, the high-pressure water pipe 7-1 is connected to the water pressure control device 7-4 and the water tank 7-5, the high-pressure water pipe 7-1 is provided with a water pressure stabilizing device 7-2 near the concave water tank 3-2, and the high-pressure water pipe 7-1 is provided with a water pressure stabilizing device 7-2 near the concave water tank 3-2. A water pressure tee 7-6 is provided, a water injection valve 7-3 is provided between the water pressure tee 7-6 on the high-pressure water pipe 7-1 and the water pressure control device 7-4, and a drainage or exhaust valve 7-7 is provided between the water pressure tee 7-6 on the high-pressure water pipe 7-1 and the water tank 7-5; the water pressure loading system 7 can apply a gradient water pressure load of a certain stable pressure to the bottom of the three-dimensional test model 10 in the model storage cavity 3 with different inclination angles through the concave water tank 3-2 at the lower part of the concave cavity 3-1.

[0057] The inclination adjustment system 8 includes a track 8-1, a pulley 8-2, a hydraulic jack 8-3, an inclination swivel 8-4, an adjustment plate 8-5, an inclination scale 8-6, a hydraulic oil pipe 8-7, a hydraulic pressure stabilizing device 8-8, a hydraulic valve 8-9 and a hydraulic control device 8-10. The track 8-1 is evenly spaced on the support base 1-1, and the pulleys 8-2 are evenly spaced and fixedly installed at the bottom of one side of the model storage chamber 3. The pulley 8-2 can slide left and right on the track 8-1 below it; the hydraulic jack 8-3 is located at the lower part of the other side of the model storage chamber 3, and the bottom of the hydraulic jack 8-3 is evenly spaced and fixedly installed on the support base 1-1, and corresponds to the pulley 8-2 along the direction of the track 8-1 one by one; the top of the hydraulic jack 8-3 is connected to the adjustment plate 8-5 through the inclination swivel 8-4, and the adjustment plate 8-5 can apply support loads to the model storage chamber 3 with different inclination angles through the inclination swivel 8-4. Load; further, the hydraulic jack 8-3 is provided with an inclination scale 8-6, which can display the inclination angle of the model storage chamber 3; the hydraulic oil pipe 8-7 is connected to the hydraulic jack 8-3, and the hydraulic oil pipe 8-7 is connected to the hydraulic control device 8-10, and the hydraulic pressure stabilizing device 8-8 and the hydraulic valve 8-9 are sequentially provided between the hydraulic jack 8-3 and the hydraulic control device 8-10 on the hydraulic oil pipe 8-7; the inclination adjustment system 8 can raise or lower the hydraulic jack 8-3 through the hydraulic control device 8-10 to adjust the inclination angle of the three-dimensional test model 10 and the concave water tank 3-2 in the model storage chamber 3. In order to facilitate the adjustment of the inclination angle, the inclination angle of the model storage chamber 3 displayed by the inclination scale 8-6 and the height after the hydraulic jack 8-3 is raised or lowered meet the following relationship:

[0058] Tilt angle ξ 0° 10° 20° 30° 40° 50° Height 0cm 20cm 40cm 60cm 80cm 100cm

[0059] like Figure 5As shown, the signal acquisition and processing system 9 includes a multi-field precursor information acquisition and processing system 9-1 and an apparent resistivity signal acquisition and processing system 9-2; the multi-field precursor information acquisition and processing system 9-1 includes an optical fiber sensor array 9-1a, an optical fiber splitter 9-1b, a grating demodulation device 9-1c, a PC for multi-field precursor information acquisition and processing 9-1d and an optical fiber cable 9-1e, the optical fiber sensor array 9-1a includes an optical fiber stress sensor 9-1a1, an optical fiber displacement sensor 9-1a2, an optical fiber acoustic emission sensor 9-1a3, an optical fiber seepage pressure sensor 9-1a4 and an optical fiber temperature sensor 9-1a5; the optical fiber stress sensor 9-1a1, the optical fiber displacement sensor 9-1a2, the optical fiber acoustic emission sensor 9-1a3, the optical fiber seepage pressure sensor 9-1a4 and the optical fiber temperature sensor 9-1a5 are connected to the optical fiber splitter 9-1b through the optical fiber cable 9-1e, and the optical fiber splitter 9-1b is connected to A grating demodulation device 9-1c, the grating demodulation device 9-1c is connected to a PC 9-1d for collecting and processing multiple fields of precursor information through an optical fiber cable 9-1e; the apparent resistivity signal collection and processing system 9-2 includes a network parallel circuit copper sheet electrode 9-2a, a WBD type network parallel electrical method instrument 9-2b, a PC 9-2c for assisted drawing with Surfer software, and a copper enameled signal transmission wire 9-2d; the network parallel circuit copper sheet electrode 9-2a is connected to a WBD type network parallel electrical method instrument 9-2b through a copper enameled signal transmission wire 9-2d, and the WBD type network parallel electrical method instrument 9-2b is connected to a PC 9-2c for assisted drawing with Surfer software through a copper enameled signal transmission wire 9-2d; through the collection and analysis of multiple fields of precursor information and apparent resistivity signals, the evolution law and coupling characteristics of multiple fields of precursor information such as bottom plate rock layer stress, displacement, cracks, seepage, temperature, etc. during the process of water inrush from the bottom plate of an inclined coal seam above pressurized water are studied. The optical fiber cable 9-1e and the copper enameled signal transmission wire 9-2d are both led out from the sealed threading hole at the back of the model storage chamber 3 and are respectively connected to the PC 9-1d for multi-field precursor information collection and processing and the PC 9-2c for Surfer software assisted drawing to ensure the sealing of the model storage chamber 3; further, the optical fiber sensor array 9-1a and the network parallel circuit copper sheet electrode 9-2a are small in size and are buried at a relatively long distance from each other in the three-dimensional test model 10, which can effectively avoid destroying the integrity of the coal seam bottom plate 10-1 rock layer in the three-dimensional test model 10 and forming a dominant water inrush channel.

[0060] The three-dimensional test model 10 includes a coal seam floor 10-1, a mining coal seam 10-2 and a coal seam roof 10-3; the upper part of the coal seam floor 10-1 is connected to the mining coal seam 10-2, and the upper part of the mining coal seam 10-2 is connected to the coal seam roof 10-3; the left and right sides of the coal seam floor 10-1, the mining coal seam 10-2 and the coal seam roof 10-3 are connected to a horizontal loading system 5 through a side loading plate 4-1, the top of the coal seam roof 10-3 is connected to a vertical loading system 6 through a top loading plate 4-2, and the bottom of the coal seam floor 10-1 is connected to a water pressure loading system 7 through a concave water tank 3-2; the rock formation of the coal seam floor 10-1 At least four optical fiber stress sensors 9-1a1, optical fiber displacement sensors 9-1a2, optical fiber acoustic emission sensors 9-1a3, optical fiber seepage pressure sensors 9-1a4, optical fiber temperature sensors 9-1a5 and network parallel circuit copper electrode 9-2a are buried in a certain arrangement; further, the three parts of the coal seam floor 10-1, the mined coal seam 10-2 and the coal seam roof 10-3 in the three-dimensional test model 10 are all made of fluid-solid coupling similar simulation materials, which can better simulate the infiltration and scouring of pressurized water into the mining-damaged cracks and the formation of water inrush channels during the water inrush from the inclined coal seam floor on the pressurized water.

[0061] The raw materials of the coal seam bottom plate 10-1 include fine sand, talcum powder, kaolin, gypsum, cement, vaseline, silicone oil and water, the raw materials of the mined coal seam 10-2 include coal powder, talcum powder, gypsum, vaseline, silicone oil and water, and the raw materials of the coal seam top plate 10-3 include coarse sand, fine sand, talcum powder, kaolin, gypsum, cement, vaseline, silicone oil and water; further, the fine sand particle size is less than 2mm, the coarse sand particle size is less than 7mm and greater than 5mm, the talcum powder fineness is 1250 mesh, the kaolin contains 45% silicon dioxide and the fineness is 400 mesh, the coal powder particle size is less than 0.1mm, the cement is high-quality white silicate cement with a strength of 32.5MPa, the vaseline is non-toxic medical grade white vaseline with a melting point of 45-60°C, the silicone oil is dimethyl silicone oil with a viscosity of 1500cs, and the water is tap water.

[0062] like Figure 6As shown, the coal seam mining simulation system 11 includes an air bag 11-1, an air pipe 11-2, a U-shaped pipe 11-3, an air release valve 11-4, an air pressure stabilizing device 11-5, an air valve 11-6 and an air control device 11-7; the air bag 11-1 includes a starting air bag 11-1a, an intermediate air bag 11-1b and a terminal air bag 11-1c, the number of the starting air bag 11-1a is one, the number of the intermediate air bags 11-1b is several, and the number of the terminal air bag 11-1c is one; one side of the starting air bag 11-1a is connected to the air control device 11-7 through the air pipe 11-2, and an air pressure stabilizing device 11-5 is arranged on the air pipe 11-2 near the starting air bag 11-1a, and the air pressure stabilizing device 11-5 is arranged on the air pipe 11-2 near the starting air bag 11-1a. An inflation valve 11-6 is provided between the device 11-5 and the inflation control device 11-7; the other side of the starting air bag 11-1a is connected to one side of the middle air bag 11-1b through an air release pipe (a U-shaped pipe is used in this embodiment, and is collectively referred to as the U-shaped pipe hereinafter), and the other side of the middle air bag 11-1b is connected to one side of the terminal air bag 11-1c through the U-shaped pipe 11-3, and the other side of the terminal air bag 11-1c is also connected to the U-shaped pipe 11-3, and the U-shaped pipe 11-3 is provided with an air release valve 11-4; further, there are a plurality of middle air bags 11-1b between the starting air bag 11-1a and the terminal air bag 11-1c, and the plurality of middle air bags 11-1b are connected to each other through the U-shaped pipe 11-3.

[0063] The air bag 11-1 is a rectangular capsule. The number and size of the air bag 11-1 are determined by the excavation range and height of the mined coal seam 10-2. The air bags 11-1 are connected in series in an S-shape and are closely arranged in sequence and embedded in the mined coal seam 10-2, and are surrounded by the mined coal seam 10-2 on all sides; further, the air pipe 11-2 passes through the transparent glass plate 3-3 and the mined coal seam 10-2 and is connected to the center of the side of the starting air bag 11-1a, the U-shaped tube 11-3 is connected to the bottom corner of the side of the air bag 11-1, and the deflation valve 11-4 on the U-shaped tube 11-3 passes through the mined coal seam 10-2 and the transparent glass plate 3-3 and is left outside the model storage chamber 3; the coal seam mining simulation system 11 can deflate the air bags 11-1 inside the mined coal seam 10-2 in sequence through the deflation valve 11-4, so as to realize the segmented and step-by-step excavation simulation of the mined coal seam 10-2.

[0064] The specific steps of the above method are as follows:

[0065] (1) Material configuration: According to the hydrogeological conditions of the inclined coal seam working face on the pressurized water to be simulated and the physical and mechanical properties of the coal seam and its top and bottom rock strata, determine the ratio of similar simulation materials for the coal seam bottom plate 10-1, the mined coal seam 10-2 and the coal seam top plate 10-3, and thereby determine the amount of various raw materials required for each rock stratum; according to the properties of the components of similar simulation materials for the coal seam bottom plate 10-1, the mined coal seam 10-2 and the coal seam top plate 10-3, weigh the various aggregates and binders required for each rock stratum strictly in proportion; mix the aggregates and binders evenly, add an appropriate amount of mixing water and stir thoroughly, and add a silicone oil regulator and stir evenly; heat vaseline to 45°C to 60°C to melt it into a liquid state, quickly mix and stir it with the similar simulation materials, prepare the fluid-solid coupling similar simulation materials, and put them into corresponding containers, waiting for model laying;

[0066] (2) Model preparation: The model storage chamber 3 is adjusted to a horizontal state through the inclination adjustment system 8, and the evenly stirred coal seam bottom plate 10-1 similar simulation material is laid on the bottom of the concave cavity 3-1 in the model storage chamber 3, and the mining coal seam 10-2 and coal seam roof 10-3 similar simulation materials are laid thereon in turn, and a certain amount of mica powder is spread between each rock layer; at the same time, during the model laying process, an optical fiber stress sensor 9-1a1, an optical fiber displacement sensor 9-1a2, an optical fiber acoustic emission sensor 9-1a3, an optical fiber seepage pressure sensor 9-1a4, an optical fiber temperature sensor 9-1a5 and a network parallel circuit copper sheet electrode 9-2a are buried at a predetermined monitoring position of the coal seam bottom plate 10-1; according to the simulated mining size and mining height of the inclined coal seam working face, a mining area corresponding to the mining size of the inclined coal seam working face is cut in the mining coal seam 10-2. The space with the same height as the mining height is replaced by the gas pack 11-1 in the coal seam mining simulation system 11, and the size and number of the gas pack 11-1 are determined by the mining parameters of the inclined coal seam working face; the gas packs 11-1 are connected in series in an S shape and are closely arranged in sequence in the excavation space of the mining coal seam 10-2, and are filled with pressurized gas with the same strength as the mining coal seam 10-2; during the model laying process, the optical fiber cable 9-1e and the copper enameled signal transmission wire 9-2d, the gas filling valve 11-6 on the gas filling tube 11-2 and the gas release valve 11-4 on the U-shaped tube 11-3 are all led out from the special sealing threading holes on the transparent glass plates 3-3 at the front and back of the model storage chamber 3 to ensure the sealing of the model storage chamber 3; the coal seam bottom plate 10-1, the mining coal seam 10-2 and the coal seam roof 10-3 are compacted and fixed to prepare a three-dimensional fluid-solid coupling similarity simulation test model;

[0067] (3) Model loading: After the three-dimensional test model 10 to be laid is dried, first, the model storage chamber 3 is adjusted to the angle of the inclined coal seam to be simulated by using the inclination adjustment system 8 and raising the hydraulic jack 8-3; secondly, a vertical load of a certain gradient is applied to the top of the three-dimensional test model 10 through the top loading plate 4-2 using the vertical loading system 6; thirdly, a horizontal load that increases linearly with the burial depth is applied to the left and right sides of the three-dimensional test model 10 through the side loading plate 4-1 using the horizontal loading system 5; finally, a water pressure load of a certain gradient is applied to the bottom of the three-dimensional test model 10 through the concave water tank 3-2 using the water pressure loading system 7, and the water pressure load applied to the three-dimensional test model 10 during similar tests is always less than the horizontal load applied;

[0068] (4) Model excavation: After the load on the three-dimensional test model 10 is balanced, all the deflation valves 11-4 and inflation valves 11-6 in the coal seam mining simulation system 11 are closed; first, the deflation valve 11-4 on the U-shaped tube 11-3 outside the terminal inflation bag 11-1c is opened to deflate the terminal inflation bag 11-1c, thereby realizing the first step of segmented excavation simulation of mining the coal seam 10-2; second, the deflation valve 11-4 on the U-shaped tube 11-3 between the terminal inflation bag 11-1c and the middle inflation bag 11-1b is opened to deflate the middle inflation bag 11-1b, thereby realizing the second step of segmented excavation simulation of mining the coal seam 10-2; third, the deflation valves 11-4 on the U-shaped tube 11-3 between the remaining middle inflation bags 11-1b are opened in turn to deflate the remaining middle inflation bags 11-1 b. Deflate in sequence to realize the third step, the fourth step, the fifth step ... ... excavation simulation of the mining coal seam 10-2; finally, open the deflation valve 11-4 on the U-shaped tube 11-3 between the middle gas bag 11-1b and the starting gas bag 11-1a, deflate the starting gas bag 11-1a, and realize the whole excavation simulation of the mining coal seam 10-2; since all the gas bags 11-1 are connected in series in an S shape and are closely arranged in sequence and embedded in the mining coal seam 10-2, by deflating the end gas bag 11-1c, the middle gas bag 11-1b and the starting gas bag 11-1a in sequence, the segmented and step-by-step excavation simulation of the mining coal seam 10-2 can be realized, and at the same time, by controlling the deflation speed and interval time of the deflation valve 11-4, the speed of excavation of the mining coal seam 10-2 can be simulated;

[0069] (5) Data acquisition: During the simulation of the segmented and step-by-step excavation of the inclined coal seam working face above confined water, the multi-field precursor information acquisition and processing system 9-1 and the apparent resistivity signal acquisition and processing system 9-2 are used to synchronously acquire the multi-field precursor information such as stress, displacement, crack, seepage, temperature, etc. of the bottom strata and the evolution law of the apparent resistivity signal of the bottom strata during the advancement of the inclined coal seam working face. Through the acquisition and analysis of the multi-field precursor information and the apparent resistivity signal, the evolution law and coupling characteristics of the multi-field precursor information such as stress, displacement, crack, seepage, temperature, apparent resistivity, etc. of the bottom strata during the water inrush from the bottom strata of the inclined coal seam above confined water are studied;

[0070] (6) Influencing factors: The hydrogeological conditions and boundary conditions of the three-dimensional experimental model 10 for mining inclined coal seams above confined water are changed, such as coal seam burial depth, coal seam inclination, roof and floor rock properties and thickness, aquifer water pressure, vertical load and horizontal load. The above experimental steps are repeated to study the influence of mining depth, coal seam inclination, aquiclude lithology and thickness, aquifer water pressure, horizontal stress and working face advancement distance on the multi-field precursor information of floor rock stress, displacement, cracks, seepage, temperature and apparent resistivity during water inrush from the floor of inclined coal seams above confined water, as well as its evolution law and coupling characteristics.

[0071] In summary, the embodiments of the present invention have the following beneficial effects:

[0072] Provided are a three-dimensional similarity test device and a test method for mining an inclined coal seam with an adjustable inclination angle in a confined aquifer. The test device and the test method can truly invert the dynamic evolution process of the generation, expansion, and penetration of cracks in the bottom rock layer of longwall mining in the inclined coal seam above confined water, and finally form a water-conducting channel; the coal seam mining simulation system of the test device can realize the controllable excavation of a three-dimensional similarity model in a confined space, and can truly simulate the step-by-step excavation of the coal seam, especially the segmented excavation of the coal seam, which is consistent with the actual coal seam mining process.

[0073] The test device realizes the adjustable inclination of the confined aquifer, the gradient distribution of the water pressure load of the inclined aquifer, and the authenticity of the gradient stress state in the vertical and horizontal directions of the inclined coal seam; in addition, the similar test model of the test device can be laid in a horizontal state, which ensures the wide application of the test device, the effectiveness of the simulation and the ease of operation, and can better carry out three-dimensional similarity simulation tests of longwall mining of inclined coal seams with different inclination angles above confined water, and predict water inrush from the bottom of inclined coal seams with different inclination angles.

[0074] The above is a detailed introduction to the three-dimensional similarity test device and test method for inclined coal seam mining with adjustable inclination angle of the confined aquifer provided by the present invention. The description of the specific embodiment is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A three-dimensional similarity test device for mining an inclined coal seam with an adjustable inclination angle of a confined aquifer, comprising a test support, an internal frame, a model storage cavity, a loading plate, a horizontal loading system, a vertical loading system, a water pressure loading system, a signal acquisition and processing system, and a three-dimensional test model, wherein the internal frame is arranged inside the test support, the model storage cavity is located inside the internal frame, the loading plate is located inside the model storage cavity, the three-dimensional test model is stored in the model storage cavity, the horizontal loading system and the vertical loading system apply horizontal pressure and vertical pressure to the three-dimensional test model through the loading plate, the water pressure loading system applies water pressure to the three-dimensional test model from the bottom, the signal acquisition and processing system is used to collect and process data signals during the test, and the three-dimensional test model includes a coal seam floor, a mining coal seam, and a coal seam roof from bottom to top; Features: It also includes a tilt adjustment system and a coal seam mining simulation system; The inclination adjustment system is used to adjust the inclination of the model storage chamber, and the inclination adjustment system includes a track, a pulley matched with the track, a hydraulic jack, a hydraulic oil pipe, a hydraulic pressure stabilizing device, a hydraulic valve and a hydraulic control device. The track is fixedly arranged on the test bracket, the pulley can slide on the track, and the pulley is fixedly installed at one end of the bottom of the model storage chamber, the hydraulic jack is rotatably connected to the other end of the bottom of the model storage chamber, one end of the hydraulic oil pipe is connected to the hydraulic jack, and the other end of the hydraulic oil pipe is connected to the hydraulic control device, and the hydraulic pressure stabilizing device and the hydraulic valve are sequentially arranged between the hydraulic jack and the hydraulic control device on the hydraulic oil pipe; The coal seam mining simulation system comprises an inflatable structure and an inflatable bag connected to the inflatable structure. The inflatable bags are connected in series in an S-shape and are closely arranged in sequence and embedded in the mining coal seam. The tail ends of the inflatable bags are connected to deflation pipes. Adjacent inflatable bags are connected by the deflation pipes. The deflation pipes are provided with deflation valves. The gas in the inflatable bags is discharged to the outside of the model storage cavity through the deflation pipes. The model storage cavity specifically includes a concave cavity, a concave water tank, a transparent glass plate and a water-permeable steel grate. The concave water tank is arranged at the lower part of the concave cavity, the front and rear parts of the concave cavity are connected with a transparent glass plate, and the upper part of the concave water tank is connected with a water-permeable steel grate. The water-permeable steel grate is a rectangular steel plate with circular through holes evenly arranged thereon. The loading plate includes a top loading plate and a side loading plate. The top loading plate applies vertical pressure to the three-dimensional test model under the action of the vertical loading system, and the side loading plate applies horizontal pressure to the three-dimensional test model under the action of the horizontal loading system. The model storage cavity is in the shape of a rectangular parallelepiped. The top loading plate and the side loading plate can adjust their angles as the model storage cavity is tilted, so that the top loading plate is always parallel to the bottom surface of the model storage cavity, and at the same time, the side loading plate is always parallel to the side surface of the model storage cavity. During the simulated coal seam excavation process, air is released one by one from the last air bag forward.

2. The three-dimensional similarity test device for mining inclined coal seams with adjustable inclination angle of a confined aquifer according to claim 1, Features: The inclination adjustment system also includes an inclination rotary head and an adjustment plate. The top of the hydraulic jack is connected to the adjustment plate through the inclination rotary head. The adjustment plate is connected to the bottom of the model storage cavity. The adjustment plate applies a supporting load to the model storage cavity with different inclination angles through the inclination rotary head.

3. The three-dimensional similarity test device for mining inclined coal seams with adjustable inclination angle of a confined aquifer according to claim 2, Features: The inclination adjustment system further comprises an inclination scale, which is arranged on the hydraulic jack and is used to display the inclination angle of the model storage cavity.

4. The three-dimensional similarity test device for mining inclined coal seams with adjustable inclination angle of a confined aquifer according to claim 1, Features: The inflatable bags include a starting inflatable bag, a middle inflatable bag, and a terminal inflatable bag according to their positions. The inflatable structure is connected to the starting inflatable bag, and the middle inflatable bag and the terminal inflatable bag are inflated through the starting inflatable bag, and all the inflatable bags are deflated through the deflation pipes connected to the inflatable bags.

5. The three-dimensional similarity test device for mining inclined coal seams with adjustable inclination angle of a confined aquifer according to claim 4, Features: The inflatable structure includes an inflatable tube, an inflatable pressure stabilizing device, an inflatable valve, and an inflatable control device arranged on the inflatable tube. The inflatable tube passes through the model storage cavity and is connected with the starting inflatable bag. The inflatable pressure stabilizing device, the inflatable valve, and the inflatable control device are located outside the model storage cavity.

6. The three-dimensional similarity test device for mining inclined coal seams with adjustable inclination angle of a confined aquifer according to claim 5, Features: The deflation pipe is a U-shaped pipe, which is communicated with the bottom corner of the side of the inflatable bag. The deflation valve on the U-shaped pipe passes through the mined coal seam and is left outside the model storage cavity.

7. The three-dimensional similarity test device for mining inclined coal seams with adjustable inclination angle of a confined aquifer according to claim 5 or 6, Features: The inflatable bag is a rectangular parallelepiped capsule.

8. A three-dimensional similarity test method for mining inclined coal seams with adjustable inclination angle of a confined aquifer using the device according to any one of claims 1 to 7, Features: The steps include: (1) Material configuration: According to the hydrogeological conditions of the inclined coal seam working face above the pressurized water to be simulated and the physical and mechanical properties of the coal seam and its roof and floor strata, the proportion of similar simulation materials for the coal seam floor, mined coal seam and coal seam roof is determined, so as to determine the amount of various raw materials required for each rock layer; according to the properties of the components of similar simulation materials for the coal seam floor, mined coal seam and coal seam roof, the required materials for each rock layer are weighed strictly in proportion, and the fluid-solid coupling similar simulation materials are prepared and loaded into the corresponding containers, waiting for the model to be laid; (2) Model preparation: The model storage cavity is adjusted to a horizontal state through the inclination adjustment system, and the evenly mixed coal seam floor similar simulation material is laid on the bottom of the model storage cavity, and the mined coal seam and coal seam roof similar simulation materials are laid thereon in sequence, and a certain amount of mica powder is spread between each rock layer; at the same time, during the model laying process, the signal acquisition end of the signal acquisition and processing system is buried at the predetermined monitoring position of the coal seam floor; according to the simulated mining size and mining height of the inclined coal seam working face, a space with the same mining size and mining height as the inclined coal seam working face is cut out in the mined coal seam, and Replaced with the inflatable bag in the coal seam mining simulation system, the size and number of the inflatable bag are determined by the mining parameters of the inclined coal seam working face; the inflatable bags are connected in series in an S shape and closely arranged in the excavation space of the mined coal seam, and filled with pressurized gas with the same strength as the mined coal seam; during the model laying process, the transmission wire at the signal acquisition end, the inflation valve on the inflation pipe and the deflation valve on the U-shaped tube are all led out from the sealed threading holes on the transparent glass plates at the front and back of the model storage cavity to ensure the sealing of the model storage cavity; the coal seam bottom plate, the mined coal seam and the coal seam roof are compacted and fixed to prepare a three-dimensional fluid-solid coupling similarity simulation test model; (3) Model loading: After the 3D test model to be laid is dry, first, the model storage cavity is adjusted to the angle of the inclined coal seam to be simulated by raising the hydraulic jack using the inclination adjustment system; secondly, a vertical load of a certain gradient is applied to the top of the 3D test model through the top loading plate using the vertical loading system; thirdly, a horizontal load that increases linearly with the burial depth is applied to the left and right sides of the 3D test model through the side loading plates using the horizontal loading system; finally, a water pressure load of a certain gradient is applied to the bottom of the 3D test model using the water pressure loading system, and the water pressure load applied to the 3D test model during similar tests is always less than the horizontal load applied; (4) Model excavation: After the load on the three-dimensional test model is balanced, all the deflation valves and inflation valves in the coal seam mining simulation system are closed; first, the deflation valve on the U-shaped tube connected to the end inflation bag is opened to deflate the end inflation bag to achieve the first step of segmented excavation simulation of simulated mining of the coal seam; second, the deflation valve on the U-shaped tube between the end inflation bag and the middle inflation bag directly connected to it is opened to deflate the middle inflation bag to achieve the second step of segmented excavation simulation of simulated mining of the coal seam; third, the deflation valves on the U-shaped tubes between the remaining middle inflation bags are opened in turn to deflate the remaining middle inflation bags in turn to achieve the step-by-step excavation simulation of simulated mining of the coal seam; finally, the deflation valve on the U-shaped tube between the middle inflation bags directly connected to the start inflation bag is opened to deflate the start inflation bag to achieve the entire excavation simulation of simulated mining of the coal seam; (5) Data acquisition: During the simulation of step-by-step and segmented excavation of the inclined coal seam working face above confined water, the multi-field precursor information of the floor rock strata stress, displacement, cracks, seepage, temperature and the evolution law of the floor rock strata apparent resistivity signal during the advancement of the inclined coal seam working face are synchronously collected. Through the collection and analysis of multi-field precursor information and apparent resistivity signals, the evolution law and coupling characteristics of the multi-field precursor information of the floor rock strata stress, displacement, cracks, seepage, temperature and apparent resistivity during the water inrush from the floor of the inclined coal seam above confined water are studied; (6) Influencing factors: The hydrogeological conditions and boundary conditions of the three-dimensional experimental model of inclined coal seam mining above confined water were changed, and the above experimental steps were repeated to study the influence of mining depth, coal seam inclination, lithology and thickness of the impermeable layer, water pressure of the aquifer, horizontal stress, and working face advancement distance on the multi-field precursor information of the floor rock layer stress, displacement, cracks, seepage, temperature, and apparent resistivity during the process of water inrush from the floor of the inclined coal seam above confined water, as well as its evolution law and coupling characteristics.

9. The three-dimensional similarity test method for mining inclined coal seams with adjustable inclination angle of a confined aquifer as claimed in claim 8, Features: In the (4) model excavation process, the speed of coal seam excavation can be simulated by controlling the air release speed and interval time of the air release valve.

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