An experimental device for load transfer action of water body under thick sandstone aquifer separation layer

Abstract

The present application relates to the technical field of water pressure of water separation layer, disclose a kind of thick sandstone aquifer under the water body load transfer effect experimental device of water separation layer, including transparent observation baffle, simulation experiment frame, frame side baffle, simulation rock stratum, water separation layer water bag, constant pressure water supply mechanism and multiple stress sensors;The simulation experiment frame is the cuboid frame structure of profile steel welding, the simulation rock stratum is laid in the inside of the simulation experiment frame, and the transparent observation baffle is fixedly installed in the front side of the simulation experiment frame.The present application has the following advantages and effects: the process of water separation layer water transferring overburden load is quantitatively simulated, the load transfer effect of water separation layer water body under different conditions is explored by adjusting water pressure, rock stratum thickness, aquifer burial depth parameters, and the influence law of water pressure, rock stratum thickness, aquifer burial depth and other factors on water separation layer water body load transfer can be revealed.

Description

Technical Field

[0001] This invention relates to the field of hydrodynamic and hydraulic pressure technology, and in particular to an experimental device for the load transfer effect of delamination water under a thick sandstone aquifer. Background Technology

[0002] Thick sandstone aquifers of the Luohe Formation are found in the overburden of coal seams in my country's basins and surrounding areas. Mining under these conditions can easily lead to aquifer delamination and water accumulation beneath the aquifer. Under certain conditions, this water can communicate with water-conducting fractures, triggering water inrush disasters. The presence of aquifer water alters the load distribution within the overburden, and the transfer of load from the aquifer water to the thick sandstone aquifer is a significant factor influencing the water inrush process.

[0003] Currently, similar simulation experiments have been conducted using delamination water inrush testing devices. However, existing devices mainly focus on simulating overburden failure and fracture development, lacking detailed simulation and synchronous monitoring of the load transfer process of the delamination water itself. In particular, there is a lack of effective experimental methods for different water pressure and rock layer thickness conditions, the dynamic response relationship between water pressure and rock layer stress, and the law of load in multi-layered rock layers. Therefore, this paper proposes an experimental device for the load transfer effect of delamination water under a very thick sandstone aquifer. Summary of the Invention

[0004] The purpose of this invention is to provide an experimental device for the load transfer of delamination water under a thick sandstone aquifer, which can reveal the influence of factors such as water pressure, rock layer thickness, and aquifer burial depth on the load transfer of delamination water.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: an experimental device for the load transfer effect of delamination water under a thick sandstone aquifer, comprising a transparent observation baffle, a simulated experimental platform, a side baffle of the platform, a simulated rock layer, a delamination water bag, a constant pressure water supply mechanism, and multiple stress sensors. The simulation test platform is a rectangular frame structure welded from steel sections. The simulated rock strata are laid inside the simulation test platform. The transparent observation baffle is fixedly installed on the front side of the simulation test platform. Multiple side baffles of the platform are fixedly installed on the sides and rear side of the simulation test platform, respectively. The abscission water bag is placed in a pre-set abscission space in the simulated rock strata to simulate the water body in the abscission space under the thick sandstone aquifer. Multiple stress sensors are arranged between the top and bottom surfaces of the delamination water bag and the adjacent simulated rock layer. The multiple stress sensors are electrically connected to an external data acquisition device through sensor wires. The stress sensors are used to collect stress response data of the simulated rock layer. The constant pressure water supply mechanism includes a water tank, a variable frequency water pump, and water pipes installed on the ground. The inlet of the variable frequency water pump is fixedly connected to the water tank through the water pipes, and the outlet of the variable frequency water pump is fixedly connected to the separation water bag through the water pipes. A water pressure gauge is installed on the water pipes, and the water pressure gauge is close to the outlet of the variable frequency water pump.

[0006] By adopting the above technical solution, a supporting structure is constructed using a steel frame simulation experimental platform, side baffles, and transparent observation baffles. Simulated rock strata are laid within the supporting structure, and a space is reserved in the simulated rock strata to hold the absorptive water bag. This simulates the state of absorptive water under different water pressures in a thick sandstone aquifer. A closed-loop constant pressure water supply system consisting of a variable frequency water pump, a water tank, and the absorptive water bag is used to quantitatively simulate the process of absorptive water transferring loads between the overlying rock strata. By adjusting the geometric parameters of water pressure, rock stratum thickness, and aquifer depth, the load transfer effect of absorptive water under different conditions is explored. Multiple stress sensors are deployed at the contact surface between the absorptive water bag and the overlying rock strata to capture the stress response data of the overlying rock strata in real time when the water pressure changes. This allows for a quantitative study of the load transfer path and magnitude of "water pressure → rock strata," achieving synchronous dynamic monitoring of water pressure and stress in different rock strata during the load transfer process. This reveals the influence of factors such as water pressure, rock stratum thickness, and aquifer depth on the load transfer of absorptive water.

[0007] A further feature of the present invention is that the simulated rock layers are laid layer by layer according to a preset similarity ratio, and the thickness, layering order, density and physical and mechanical parameters of each rock layer are matched with the geological conditions under the thick sandstone aquifer on site.

[0008] By adopting the above technical solution, during the experiment, based on the similarity simulation theory, simulated rock layers and simulated coal seams were laid layer by layer in the simulation experimental platform according to the preset similarity ratio. The thickness, layering order, density and physical and mechanical parameters of each rock layer were strictly controlled to make it consistent with the on-site strata conditions under the thick sandstone aquifer. This improved the fidelity and reliability of the experimental model, enabling the experimental conclusions to be effectively inverted and extended to actual engineering conditions, and enhancing the engineering guidance value of the experimental results.

[0009] A further configuration of the present invention is that the plurality of stress sensors are divided into a first group of stress sensors and a second group of stress sensors; The first set of stress sensors is located between the upper waterproof layer and the overlying rock layer on the top surface of the delamination water bag; The second set of stress sensors is placed between the lower waterproof layer and the lower rock layer on the bottom surface of the delamination water bag.

[0010] By adopting the above technical solution, this layout can monitor the stress distribution of water pressure transmission upward and downward, realize the separate monitoring of the two-way load transmission path, clearly distinguish the different action mechanisms of water pressure on the overlying and underlying rock strata, provide a basis for targeted prevention and control, and realize the synchronous dynamic monitoring of water pressure and rock strata stress during load transmission.

[0011] A further configuration of the present invention is as follows: in the constant pressure water supply mechanism, a check valve, a water pressure gauge and a water outlet valve are sequentially provided on the water pipe; an inlet valve is provided on the water pipe between the variable frequency water pump and the water tank; the check valve is installed between the water pressure gauge and the separation water bag; the water pressure gauge is installed between the check valve and the water outlet valve; and the water outlet valve is installed between the water pressure gauge and the variable frequency water pump.

[0012] By adopting the above technical solution, a check valve (to prevent backflow and pressure loss when the water pressure in the absorptive water bag suddenly drops), a pressure gauge (to display the current pressure value in real time), an outlet valve (to control the water injection on / off), and an inlet valve are sequentially integrated on the water pipe. The variable frequency water pump serves as the core actuator. By adjusting the power supply frequency, the variable frequency water pump changes the motor speed of the pump, thereby adjusting and maintaining the water pressure in the water bag in real time. This simulates the state of the absorptive water body under different water pressure conditions, thus constructing a complete pressure closed-loop control system. The check valve ensures the stability of the pressure, the outlet / inlet valve facilitates water injection / stopping operations during the experiment, and the pressure gauge provides instant feedback, effectively ensuring the constancy and repeatability of the water pressure conditions during the experiment.

[0013] A further feature of the present invention is that the material of the ablative water bag is TPU thermoplastic polyurethane, which is a flat bladder, and a PVC pagoda connector is hot-melt welded to one side of the flat bladder.

[0014] By adopting the above technical solution, the planar dimensions of the capsule are 2000mm in length and 250mm in width. A PVC pagoda connector with an inner diameter of 8mm is heat-fused to one side of the capsule. The PVC pagoda connector is used to connect the water supply pipe. Before burying the exfoliation water bag, an airtightness test should be performed: fill the water bag with 0.2MPa of compressed air, then immerse it in clean water for 2 minutes. No air bubbles should escape to pass the test. The TPU material has good flexibility and high conformity, which can perfectly adapt to the unevenness of the rock stratum interface and ensure uniform water pressure transmission. The flat design conforms to the geometric characteristics of the "layered fracture" of the exfoliation space. The airtightness test procedure ensures zero leakage during the experiment, eliminates pressure fluctuation interference caused by water loss, and significantly improves the stability of the experiment. A further feature of the present invention is that the absorptive water bag is laid flat in the simulated rock layer, and the absorptive water bag is without wrinkles, suspension, or twisting, and is closely attached to the upper and lower rock layers.

[0015] By adopting the above technical solution, the actual separation space is simulated to be "filled" with water and in "good contact", avoiding local stress concentration or poor contact caused by water bag folds or suspension, ensuring that water pressure can be uniformly and realistically transmitted to the entire rock stratum contact surface, and improving the accuracy and representativeness of stress data acquisition.

[0016] A further feature of the present invention is that the simulation experimental platform is made of 50mm×50mm square hollow steel welded into a cuboid frame, with the internal clear dimensions of the frame being 2000mm in length, 300mm in width, and 1500mm in height, and the front side of the simulation experimental platform is open.

[0017] By adopting the above technical solution, the size design is determined based on the similarity ratio and laboratory space conditions, providing sufficient model space to lay out the complete stratigraphic sequence; the 300mm width design is suitable for the assumption of a two-dimensional plane strain model; the square steel welded frame ensures the rigidity and stability of the overall structure, and can withstand the gravity load of the overlying rock strata without significant deformation; the opening on the front side is used to install a transparent observation baffle.

[0018] A further feature of the present invention is that the transparent observation baffle is a surface-hardened PC endurance board with a thickness of not less than 12mm, and is detachably fastened to the simulation experiment stand by screws and nuts.

[0019] By adopting the above technical solutions, the transparent material facilitates full-process visual observation of the changes in the spatial morphology of the ablation layer and the expansion process of the water bag; the high-strength baffle effectively constrains the ablation water bag from bulging forward under the pressure of the overlying rock strata, so that the water pressure energy is concentrated and transmitted in the vertical direction, which is more in line with the mechanical boundary conditions of vertical loading of ablation water in real strata; the transparent observation baffle has reserved holes at the installation position of the ablation water bag for inserting water supply pipes.

[0020] The beneficial effects of this invention are as follows: by using a separation water bag in conjunction with a constant pressure water supply mechanism, the state of the separation water body under different water pressure conditions is simulated. Multiple stress sensors are arranged between the upper and lower water-resistant layers and the rock layer on the top and bottom surfaces of the separation water bag, realizing synchronous dynamic monitoring of water pressure and rock layer stress during load transfer. The stress sensors and water pressure gauges work together to monitor and can simultaneously acquire water pressure and rock layer stress response data, revealing the influence of factors such as water pressure, rock layer thickness, and aquifer burial depth on load transfer. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 For the present invention Figure 1 Schematic diagram of the cross-sectional structure at point AA; Figure 3 For the present invention Figure 1 Schematic diagram of the cross-sectional structure at point BB; Figure 4 This is a schematic diagram of the structure of the delamination water bag of the present invention; Figure 5 For the present invention Figure 4 A schematic diagram of the cross-sectional structure at point CC.

[0023] In the diagram: 1. Transparent observation baffle; 2. Screw and nut; 3. Simulation experimental platform; 4. Side baffle of the platform; 5. Check valve; 6. Water pressure gauge; 7. Inlet valve; 8. Outlet valve; 9. Water pipe; 10. Variable frequency water pump; 11. Water tank; 12. Simulated rock strata; 13. Delamination water bag; 14. Pagoda connector; 15. Stress sensor; 16. Sensor wire. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Example 1, Reference Figures 1-3 This embodiment proposes an experimental device for the load transfer of delamination water under a thick sandstone aquifer, including a transparent observation baffle 1, a simulated experimental platform 3, a side baffle 4 of the platform 4, a simulated rock layer 12, a delamination water bag 13, a constant pressure water supply mechanism, and multiple stress sensors 15. The simulation test platform 3 is a rectangular frame structure welded from steel sections. The simulated rock layer 12 is laid inside the simulation test platform 3. The transparent observation baffle 1 is fixedly installed on the front side of the simulation test platform 3, and multiple side baffles 4 are fixedly installed on the sides and rear side of the simulation test platform 3 respectively. The water bag 13 is constrained in the horizontal direction to prevent it from bulging out to the front and rear sides under the pressure of the overlying rock layer. The abscission water bag 13 is placed in the pre-set abscission space in the simulated rock layer 12 to simulate the water body in the abscission space under the thick sandstone aquifer; Multiple stress sensors 15 are arranged between the top and bottom surfaces of the delamination water bag 13 and the adjacent simulated rock layer 12. The multiple stress sensors 15 are electrically connected to an external data acquisition device through sensor wires 16. The stress sensors 15 are used to collect stress response data of the simulated rock layer 12. The constant pressure water supply mechanism includes a water tank 11, a variable frequency water pump 10 and a water pipe 9 installed on the ground. The inlet of the variable frequency water pump 10 is fixedly connected to the water tank 11 through the water pipe 9, and the outlet of the variable frequency water pump 10 is fixedly connected to the separation water bag 13 through the water pipe 9. A water pressure gauge 6 is installed on the water pipe 9 and is close to the outlet of the variable frequency water pump 10. The supporting structure is constructed using a steel frame simulation experimental platform 3, side baffles 4, and transparent observation baffles 1. Simulated rock strata 12 are laid inside the supporting structure, and a space for holding a water bag 13 is reserved in the simulated rock strata 12 to simulate the state of the water body under different water pressures in a thick sandstone aquifer. A closed-loop constant pressure water supply system is constructed using a variable frequency water pump 10, a water tank 11, and the water bag 13 to quantitatively simulate the process of load transfer of the water body in the overlying rock strata. By adjusting the geometric parameters of water pressure, rock stratum thickness, and aquifer burial depth, the load transfer effect of the water body under different conditions is explored. Multiple stress sensors 15 are deployed at the contact surface between the water bag 13 and the overlying rock strata to capture the stress response data of the overlying rock strata in real time when the water pressure changes. This allows for a quantitative study of the load transfer path and magnitude of "water pressure → rock strata", realizing synchronous dynamic monitoring of water pressure and stress in different rock strata during the load transfer process.

[0026] Example 2, Reference Figures 2-3 Based on Example 1, simulated rock layer 12 is laid layer by layer according to a preset similarity ratio. The thickness, layering sequence, density and physical and mechanical parameters of each rock layer are matched with the geological conditions under the thick sandstone aquifer on site. Simulated rock layer 12 is laid layer by layer to ensure that the model corresponds one-to-one with the geological conditions on site in terms of thickness sequence, layering interface and compaction. Multiple stress sensors 15 are divided into a first group of stress sensors and a second group of stress sensors. The first group of stress sensors is set between the upper water-proof layer on the top surface of the delamination water bag 13 and the overlying rock layer. The second group of stress sensors is set between the lower water-proof layer on the bottom surface of the delamination water bag 13 and the lower rock layer. This layout can monitor the stress distribution of water pressure transmitted upward and downward respectively, realizing the separate monitoring of the bidirectional load transmission path. In the constant pressure water supply mechanism, a check valve 5, a water pressure gauge 6, and an outlet valve 8 are sequentially installed on the water pipe 9. An inlet valve 7 is installed on the water pipe 9 between the variable frequency water pump 10 and the water tank 11. The check valve 5 is installed between the water pressure gauge 6 and the separation water bag 13. The water pressure gauge 6 is installed between the check valve 5 and the outlet valve 8. The outlet valve 8 is installed between the water pressure gauge 6 and the variable frequency water pump 10. The variable frequency water pump 10 changes the motor speed by adjusting the power supply frequency, thereby adjusting and maintaining the water pressure in the water bag in real time, thus constructing a complete pressure closed-loop control system.

[0027] Example 3, Reference Figures 4-5 Based on Example 1 or Example 2, the material of the absorptive water bag 13 is TPU thermoplastic polyurethane, which is a flat bladder. A PVC pagoda connector 14 is heat-fused to one side of the bladder. The planar dimensions of the bladder are 2000mm in length and 250mm in width. A PVC pagoda connector with an inner diameter of 8mm is heat-fused to one side of the bladder. The PVC pagoda connector 14 is sealed to the water supply pipe 9. The absorptive water bag 13 should be tested for air tightness before being buried: 0.2MPa of compressed air is filled into the water bag, and then it is immersed in clean water for 2 minutes. No air bubbles escape, which is considered qualified. The water bag 13 is laid flat in the simulated rock layer. The water bag 13 is without wrinkles, suspension, or twisting, and is closely attached to the upper and lower rock layers. The simulation test stand 3 is made of 50mm×50mm square hollow steel welded into a cuboid frame. The internal clear dimensions of the frame are 2000mm long, 300mm wide and 1500mm high. The front side of the simulation test stand 3 is open. The transparent observation baffle 1 is a surface-hardened PC endurance board with a thickness of not less than 12mm. It is detachably fastened to the simulation experiment stand 3 by screws and nuts 2. The transparent observation baffle 1 has a reserved hole corresponding to the installation position of the separation water bag 13 for inserting the water supply pipe.

[0028] This invention has the following effects: By using a separation water bag 13 in conjunction with a constant pressure water supply mechanism, the state of the separation water body under different water pressure conditions is simulated. Multiple stress sensors 15 are arranged between the upper and lower water-proof layers and the rock layer on the top and bottom surfaces of the separation water bag 13, realizing synchronous dynamic monitoring of water pressure and rock layer stress during load transfer. The stress sensors 15 and the water pressure gauge work together to monitor and simultaneously acquire water pressure and rock layer stress response data, which can reveal the influence of factors such as water pressure, rock layer thickness, and aquifer burial depth on load transfer, providing experimental basis and theoretical support for the study of coal mine separation water inrush mechanism and disaster prevention.

Claims

1. An experimental device for the transfer of loads by delamination water beneath a thick sandstone aquifer, characterized in that, It includes a transparent observation baffle, a simulated experimental platform, side baffles of the platform, simulated rock strata, a delamination water bag, a constant pressure water supply mechanism, and multiple stress sensors; The simulation test platform is a rectangular frame structure welded from steel sections. The simulated rock strata are laid inside the simulation test platform. The transparent observation baffle is fixedly installed on the front side of the simulation test platform. Multiple side baffles of the platform are fixedly installed on the sides and rear side of the simulation test platform, respectively. The abscission water bag is placed in a pre-set abscission space in the simulated rock strata to simulate the water body in the abscission space under the thick sandstone aquifer. Multiple stress sensors are arranged between the top and bottom surfaces of the delamination water bag and the adjacent simulated rock layer. The multiple stress sensors are electrically connected to an external data acquisition device through sensor wires. The stress sensors are used to collect stress response data of the simulated rock layer. The constant pressure water supply mechanism includes a water tank, a variable frequency water pump, and water pipes installed on the ground. The inlet of the variable frequency water pump is fixedly connected to the water tank through the water pipes, and the outlet of the variable frequency water pump is fixedly connected to the separation water bag through the water pipes. A water pressure gauge is installed on the water pipes, and the water pressure gauge is close to the outlet of the variable frequency water pump.

2. The experimental device for load transfer of delamination water beneath a thick sandstone aquifer according to claim 1, characterized in that: The simulated rock layers are laid out layer by layer according to a preset similarity ratio, and the thickness, layering order, density and physical and mechanical parameters of each rock layer are matched with the geological conditions under the thick sandstone aquifer on site.

3. The experimental device for load transfer of delamination water beneath a thick sandstone aquifer according to claim 1, characterized in that, The multiple stress sensors are divided into a first group of stress sensors and a second group of stress sensors; The first set of stress sensors is located between the upper waterproof layer and the overlying rock layer on the top surface of the delamination water bag; The second set of stress sensors is placed between the lower waterproof layer and the lower rock layer on the bottom surface of the delamination water bag.

4. The experimental device for load transfer of delamination water beneath a thick sandstone aquifer according to claim 1, characterized in that: The water pipe is equipped with a check valve and an outlet valve in sequence. The water pipe between the variable frequency water pump and the water tank is equipped with an inlet valve. The check valve is installed between the water pressure gauge and the separation water bag. The water pressure gauge is installed between the check valve and the outlet valve. The outlet valve is installed between the water pressure gauge and the variable frequency water pump.

5. The experimental device for load transfer of delamination water beneath a thick sandstone aquifer according to claim 1, characterized in that: The absorptive water bag is made of TPU thermoplastic polyurethane and has a flat bladder shape. A PVC pagoda connector is hot-melt welded to one side of the absorptive water bag.

6. The experimental device for load transfer of delamination water beneath a thick sandstone aquifer according to claim 1, characterized in that, The absorptive water bag is laid flat in the simulated rock layer, and the absorptive water bag is without wrinkles, suspension, or twisting.

7. The experimental apparatus for load transfer in a thick sandstone aquifer according to claim 1, characterized in that, The simulation test stand is made of 50mm×50mm square hollow steel welded into a cuboid frame. The internal clear dimensions of the frame are 2000mm in length, 300mm in width, and 1500mm in height. The front side of the simulation test stand is open.

8. The experimental device for load transfer of delamination water beneath a thick sandstone aquifer according to claim 7, characterized in that: The transparent observation baffle is a surface-hardened PC endurance board with a thickness of not less than 12mm, and is detachably fastened to the simulation experiment stand by screws and nuts.

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