Physical test device for accurately simulating underground water level change of coal mining ground

Abstract

The utility model discloses a physical test device for accurately simulating ground phreatic water level changes in coal mining, and belongs to the technical field of coal mining processes. Comprising a box body structure formed by a bottom plate arranged on a fixed boundary, side plates arranged on the two sides and acrylic plates arranged on the front portion and the rear portion, a stratum model is arranged in the box body structure, a loading device is arranged at the top of the stratum model and comprises a pressurization air cylinder and a piston rod, and grouting drilling is simulated in the stratum model through a PVC pipe; the drilling depth is set according to test requirements, a water bag used for simulating a phreatic bed is arranged in the stratum model, and a stress sensor is arranged in a simulated roof rock stratum of the stratum model and used for monitoring pressure in the roof rock stratum. The structure is simple, the visualization degree is high, and various visualization simulation test processes can be completed at a time.

Description

Technical Field

[0001] The utility model relates to the technical field of coal mining technology, and is particularly suitable for a physical test device for accurately simulating ground water level changes in coal mining. Background Art

[0002] Coal mining is very likely to drain coal-bearing aquifers, causing the water level of the aquifer to drop and destroying the regional hydrogeological conditions. Groundwater systems, especially the shallow groundwater of the Quaternary system, have important protection value. The research, development and application of water conservation mining technology are of great significance to alleviating the contradiction between water resources and coal mining and achieving sustainable development of the ecological environment in my country's mining areas.

[0003] The prior art with publication number CN105675846A discloses a foundation pit excavation model test device with coordinated lifting of the phreatic level and the pressure head. It includes a model box, a water tank, a symmetrical surface retaining unit, a foundation pit support structure, a pressure-bearing overhead layer, a pressure-bearing head adjustment system and a measurement system; the model box includes a model box frame, a reaction plate, etc.; the water tank is arranged in the upper right corner of the model box; the symmetrical surface retaining unit is fixed to the model box frame by bolts; the pressure-bearing overhead layer is arranged at the bottom of the model box and connected to the pressure-bearing head adjustment system; the pressure-bearing head adjustment system consists of a water pressure gauge, a Marriott bottle and a bracket; it can only simulate the foundation pit problems caused by the lifting of the phreatic level and the pressure head, and the stratum structure simulation is rough, and it is impossible to simulate the changes in the phreatic layer and the impact on the stratum after grouting.

[0004] At present, there are many indoor physical simulation devices for rock movement in coal mining, but there are few accurate simulation devices for the change of ground water level in coal mining. In order to study the change law of ground water level in shallow coal seam surface drilling gangue fluidized filling water conservation mining, it is necessary to design a new type of physical similarity simulation device. Utility Model Content

[0005] In order to solve the above technical problems, the utility model discloses a physical test device for accurately simulating the change of ground water level in coal mining, which has a simple structure and is convenient to use and observe.

[0006] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a physical test device for accurately simulating the change of ground water level in coal mining, including a model laying system of a box structure, the model laying system includes a fixed boundary as the bottom plate of the box, a bottom plate is arranged above the fixed boundary, two side plates are arranged in parallel on the left and right sides of the bottom plate, and matching transparent acrylic plates are arranged on the front and back of the bottom plate to form a rectangular box, a stratum model is arranged in the rectangular box, and a loading device matching the rectangular box is arranged on the top of the stratum model, and the loading device includes a top plate arranged on the top of the simulated stratum, and a pressurized cylinder is arranged on the top plate through a piston rod;

[0007] The stratum model includes a water-proof key layer and a top rock layer arranged below the surface soil, wherein a water bag is arranged on the top of the water-proof key layer, a plurality of water outlet holes are arranged below the water bag, a plurality of stress sensors for monitoring the pressure in the top rock layer are arranged at intervals in the top rock layer, and a bottom rock layer is arranged below the top rock layer;

[0008] PVC pipes are used to simulate grouting boreholes A and B that are vertically set from the top of the formation model to the inside to simulate the grouting process, wherein the grouting borehole A is pre-laid below the key waterproof layer, and the grouting borehole B is pre-laid in the rock layer above the top rock layer; the PVC pipes simulating the grouting boreholes A and B are connected to grouting pumps.

[0009] Furthermore, a water pressure gauge is connected to the water bag side.

[0010] Furthermore, the water bag is made of PVC material, and a square through hole is provided in the middle of the water bag for the grouting borehole A and the grouting borehole B to pass through.

[0011] Furthermore, symmetrical screw holes are opened on the front and rear edges of the two side panels, and the transparent acrylic plate is fixedly connected to the screw holes of the side panels by screws, and the lowermost end of the transparent acrylic plate is located at the upper end of the mined coal seam, and the uppermost end of the transparent acrylic plate is located at the uppermost end of the entire stratum model.

[0012] The beneficial effects of the utility model are that the device has novel design, convenient operation, high visualization, and can complete the following multiple visualization simulation tests at one time:

[0013] (1) It can realize the visual simulation of the whole process of coal seam excavation;

[0014] (2) It can realize the simulation test of initial ground stress under different depth conditions;

[0015] (3) It can realize the visual simulation of the whole process of gangue fluidized filling mining;

[0016] (4) It can realize the visual simulation of the change of water level under different water pressure conditions of the diving layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a physical test device for accurately simulating ground water level changes in coal mining according to the utility model;

[0018] Figure 2 It is a schematic diagram of the structure of the water bag in the utility model;

[0019] Figure 3 It is a schematic diagram of the bottom surface of the water bag in the utility model.

[0020] In the figure: 1-fixed boundary; 2-bottom plate; 3-side plate; 4-screw; 5-pressurized cylinder; 6-piston rod; 7-grouting borehole A; 8-grouting borehole B; 9-top plate; 10-water bag; 11-water pressure gauge; 12-stress sensor; 13-water-proof key layer; 14-top plate rock layer; 15-mining rock layer; 16-bottom plate rock layer; 17-water outlet hole; 18-transparent acrylic plate. DETAILED DESCRIPTION

[0021] The embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0022] Assume that the design production capacity of a mine in a certain mining area is 5.00Mt / a, and the main coal seam is 4-2# coal. The coal seam is buried at a depth of about 170m, and the average thickness of the 4-2# coal seam is 2.5m. The surface groundwater layer overlying the coal seam is highly water-rich. Considering the requirements for surface vegetation and ecological environment protection, as well as reducing the amount of water inflow and potential disasters of water inrush during mining at the working face, water-saving coal mining operations are required. Combined with the physical test device of the utility model for accurately simulating the change of ground groundwater level in coal mining, the specific steps are described as follows:

[0023] like Figure 1 As shown, two side panels 3, the bottoms of the two side panels 3 are fixed on the fixed boundary 1, and are in close contact with the top panel 9 and the bottom panel 2;

[0024] The top plate 9 is a combined plate structure, and its two ends are in close contact with the side plates 3;

[0025] The bottom plate 2 is a combined plate structure, and its two ends are in close contact with the side plates 3;

[0026] The pressurized cylinder 5 is arranged just above the model, and its piston rod 6 is retractable, and the piston rod 6 is extended to be in close contact with the model top plate 9;

[0027] The transparent acrylic plate 18 has symmetrical screw holes on the front and rear edges of the two side plates 3. The transparent acrylic plate 18 is fixedly connected to the side plates 3 by screws 4 to achieve closure in the front and rear directions of the simulation experiment and create three-dimensional stress conditions. The lower end of the transparent acrylic plate 18 is located at the upper end of the mined coal seam 15, and the upper end of the transparent acrylic plate 18 is located at the upper end of the entire model, which is convenient for excavation of the mined coal seam 15. Since the transparent acrylic plate 18 is used, visualization can be achieved during the entire simulation experiment.

[0028] Grouting filling system

[0029] Grouting borehole A7 and grouting borehole B8 are both made of PVC. Grouting borehole A is pre-laid below the water-proof key layer, and grouting borehole B8 is pre-laid in the rock layer above the top rock layer 14. According to the actual borehole spacing, the distance between grouting borehole A7 and grouting borehole B8 is designed to be 10 cm;

[0030] Grouting boreholes A7 and B8 are connected to grouting pumps to inject slurry into the model;

[0031] The water bag 10 is made of PVC and has a square through hole in the middle. The size is set according to the actual drilling spacing. It is used to simulate the diving layer and is pre-laid below the surface soil layer. The water bag 10 is provided with a water outlet hole 17, and the water in the water bag 10 can flow into the laid rock layer through the water outlet hole 17. A water pressure gauge 11 is provided at the end of the water bag 10 to monitor the water pressure in the water bag 10. Figure 2 and Figure 3 shown.

[0032] In particular, a stress sensor 12 is provided in the roof rock formation 14 for monitoring the pressure in the roof rock formation 14 .

[0033] Specifically, using the above test device, the simulation process includes:

[0034] 1. Laying rock layers. Before the test, multiple rock layers are laid in sequence on the bottom plate 2 of the simulation test bench, including the bottom plate rock layer 16, the excavation rock layer 15, the top plate rock layer 14 and the water-proof key layer 13. Stress sensors 12 are arranged between the laid top plate rock layers 14 to monitor the stress change law during the fluidized filling and water-preserving mining of shallow coal seam gangue. Scatter points are drawn on the surface of the model, and the displacement changes at different positions during the excavation process are observed by the displacement monitor. The grouting borehole A7 is pre-laid below the water-proof key layer, the grouting borehole B8 is pre-laid in the rock layer above the top plate rock layer 14, and the water bag 10 is pre-laid below the surface soil layer. At this time, no water is injected into the water bag 10, so that the grouting borehole A7 and the grouting borehole B8 are located at the through hole in the center of the water bag 10, and the size of the through hole is 40cm×20cm. After the laying is completed, transparent acrylic plates 18 are installed in front and rear of the test bench to complete the rock layer laying process;

[0035] 2. Simulate the application of initial geostress. After the rock layer is laid, a geostress of 0.25 MPa is applied to the laid rock layer. The piston rod 6 in the pressurized cylinder 5 is extended by the air compressor to contact the model top plate 9, and a fixed load is applied in the vertical direction to achieve the application of initial geostress;

[0036] 3. Simulate the water pressure of the submerged layer. Keep the state of the pressurized cylinder 5 unchanged, and apply sealant at the junction of the roof rock layer 14 and the transparent acrylic plate 18 corresponding to the water bag 10 simulating the submerged layer to prevent water from seeping out from the junction of the transparent acrylic plate 18; then, calculate the simulated water pressure value of the submerged layer to be 0.012MPa, control the water pump to apply water pressure to the water bag 10, and at the same time, the injected water overflows from the water outlet 17, and by observing the water pressure gauge 11, control the water pressure loaded in the water pump to be maintained at 0.012MPa, so that the water pressure value displayed by the water pressure gauge 11 is equal to the simulated water pressure value of the submerged layer, and complete the simulation process of applying water pressure to the submerged layer;

[0037] 4. Simulate the process of gangue fluidized filling mining. After applying water pressure to the phreatic layer, the mining rock layer 15 is gradually excavated. After one excavation is completed, it is left to stand for a period of time for observation; repeat this process to excavate the coal seam; when longitudinal water-conducting fissures appear in the rock layer above the roof rock layer 14, a small grouting pump is used to inject gangue fluidized filling slurry into the grouting borehole B8, in which gangue accounts for 70%, water accounts for 30%, and the gangue particle size is 0.01mm; when delamination occurs below the water-proof key layer 13, a small grouting pump is used to inject gangue fluidized filling slurry into the grouting borehole A7, in which gangue accounts for 70%, water accounts for 30%, and the gangue particle size is 0.01mm.

[0038] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification and equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A physical test device for accurately simulating the change of ground water level in coal mining, characterized by: The model laying system comprises a box structure, the model laying system comprises a fixed boundary (1) as the bottom plate of the box, a bottom plate (2) is arranged above the fixed boundary (1), two side plates (3) are arranged in parallel on the left and right sides of the bottom plate (2), and matching transparent acrylic plates (18) are arranged on the front and back of the bottom plate (2) to form a rectangular box, a stratum model is arranged in the rectangular box, a loading device matching the rectangular box is arranged on the top of the stratum model, and the loading device comprises a top plate (9) arranged on the top of the simulated stratum, and a pressurized cylinder (5) is arranged on the top plate (9) through a piston rod (6); The stratum model comprises a water-proof key layer (13) and a top rock layer (14) arranged below the surface soil, wherein a water bag (10) is arranged on the top of the water-proof key layer (13), a plurality of water outlet holes (17) are arranged below the water bag (10), a plurality of stress sensors (12) for monitoring the pressure in the top rock layer (14) are arranged at intervals inside the top rock layer (14), and a bottom rock layer (16) is arranged below the top rock layer (14); A PVC pipe is used to simulate a grouting borehole A (7) and a grouting borehole B (8) which are vertically arranged from the top of the formation model to the inside to simulate the grouting process, wherein the grouting borehole A (7) is pre-laid below the waterproof key layer (13), and the grouting borehole B (8) is pre-laid in the rock layer above the top plate rock layer (14); the PVC pipes simulating the grouting borehole A (7) and the grouting borehole B (8) are connected to a grouting pump.

2. The physical test device for accurately simulating ground water level changes in coal mining according to claim 1 is characterized by: The water bag (10) is connected to a water pressure gauge (11).

3. The physical test device for accurately simulating ground water level changes in coal mining according to claim 1 is characterized by: The water bag (10) is made of PVC material, and a square through hole is provided in the middle of the water bag (10) for the grouting borehole A (7) and the grouting borehole B (8) to pass through.

4. The physical test device for accurately simulating ground water level changes in coal mining according to claim 1 is characterized by: Symmetrical screw holes are provided on the front and rear edges of the two side panels (3), and the transparent acrylic panel (18) is fixedly connected to the screw holes of the side panels (3) by screws (4), and the lowermost end of the transparent acrylic panel (18) is located at the upper end of the mined coal seam (15), and the uppermost end of the transparent acrylic panel (18) is located at the uppermost end of the entire stratum model.

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