Device and method for simulating evolution of hydrophobic stress field and deformation field of confined aquifer

Abstract

The invention discloses a device and a method for simulating the evolution of a hydrophobic stress field and a deformation field of a confined aquifer. The evolution device comprises a simulation experiment frame, the simulation experiment frame is filled with a rock stratum simulation material, and a confined aquifer simulation model is arranged in the rock stratum simulation material; and an evolution monitoring system is arranged in the simulation experiment frame. The evolution method comprises the following steps: S1, laying a rock stratum simulation material and a confined aquifer simulation model in a simulation experiment frame; s2, loading mechanisms are arranged above and at the bottom end of the simulation experiment frame; s3, water is injected into the pressure-bearing water bag; s4, installing an evolution monitoring system; s5, a water outlet in the pressure-bearing water bag is opened; s6, monitoring the pressure change, the displacement track, the water flow pressure and the water flow in the model through an evolution monitoring system; and S7, obtaining an evolution result of the evolution device according to a monitoring result of the evolution monitoring system.

Description

Technical Field

[0001] The present invention relates to the field of coal mine research, and in particular to an evolution device and an evolution method for simulating the hydrophobic stress field and deformation field of a confined aquifer. Background Art

[0002] As my country's shallow coal resources decrease, deep mining becomes necessary, but complex geological conditions increase the risk of rock bursts. Mining areas in Shaanxi and Shandong, such as those affected by overburden aquifers, experience large amounts of roof drainage, exacerbating rock bursts after drainage. Examples show that prior to rock bursts, the water levels in the overburden aquifers at Gaojiabao, Shaanxi, and Longyun, Shandong, plummeted, leading to roadway damage, roof subsidence, and other disasters. Therefore, in-depth research into the impact of aquifer drainage on overburden structure and stress fields is crucial for uncovering the mechanisms of rock bursts.

[0003] In the field of geological engineering, similar material simulation experiments are a key research tool. By creating scaled-down models of actual strata in a laboratory setting, they simulate the overburden structure and stress changes after coal seam mining. These models accurately reproduce stress field shifts, the formation of collapse zones, fracture zones, and curved subsidence zones—processes that ultimately lead to surface subsidence. In particular, the water-conducting fracture zones formed by fracture zones and curved subsidence zones may increase the risk of water inrush accidents at the working face. To accurately simulate this process, simulation of confined aquifers is crucial. By combining simulations of the drainage flow field evolution in confined aquifers, we can more comprehensively understand the impact of coal seam mining on stratum structure and hydrogeological conditions, providing a scientific basis for preventing and controlling water inrush accidents in mines. However, current aquifer simulation technologies are limited and lack true fluid-structure coupling, leaving a significant gap in their practical application in mine drainage.

[0004] In summary, there is an urgent need for a new type of confined aquifer simulation device, which can perform better fluid-solid coupling simulation based on actual on-site conditions, in order to obtain better simulation results, and thus provide theoretical experimental support for on-site water drainage work. Summary of the Invention

[0005] The purpose of the present invention is to address the above problems and provide a device and method for simulating the evolution of the hydrophobic stress field and deformation field of a confined aquifer with a simple structure and better simulation effect.

[0006] In order to achieve the above object, the technical solution of the present invention is: A device for simulating the evolution of stress and deformation fields in a confined aquifer during drainage, comprising a simulation test frame, the simulation test frame being a shell structure with an open top; the simulation test frame being filled with rock formation simulation material, a confined aquifer simulation model being disposed within the rock formation simulation material, the confined aquifer simulation model being connected to a constant-pressure water column pipeline disposed outside the simulation test frame, the constant-pressure water column providing water pressure to the confined aquifer simulation model; an evolution monitoring system being disposed within the simulation test frame, and the evolution monitoring system monitoring stress and displacement changes caused to the rock formation simulation material by drainage of the confined aquifer simulation model within the simulation test frame; the confined aquifer simulation model being scaled down based on an on-site prototype; set up is the length of the on-site prototype, is the length of the confined aquifer simulation model, is the length scale, then the geometric similarity requirement between the confined aquifer simulation model and the field prototype is ; Apparent density scale is ; Strength scale is ;in 、 Represent the apparent density of the corresponding parts of the prototype and model respectively.

[0007] Furthermore, the rock formation simulation material includes bottom plate simulation material, coal seam simulation material, roof plate simulation material, and overlying rock formation simulation material. The bottom plate simulation material, coal seam simulation material, roof plate simulation material, and overlying rock formation simulation material are all made by mixing sand, lime, gypsum, and water in proportion; the bottom plate simulation material, coal seam simulation material, roof plate simulation material, pressurized aquifer simulation model, and overlying rock formation simulation material are laid in layers from bottom to top in the simulation experimental frame.

[0008] Furthermore, the pressurized aquifer simulation model includes a pressurized water bag and a spring support mechanism. Several spring support mechanisms are arranged side by side in the pressurized water bag and the interior of the pressurized water bag is supported by the spring support mechanism. The pressurized water bag is filled with sand and the sand is located in the gap between the spring support mechanism and the inner wall of the pressurized water bag; water inlets are provided at both ends of the pressurized water bag and are connected to the constant pressure water column pipeline through the water inlets, and a water discharge port is provided in the middle of the pressurized water bag; control valves are provided at the water inlet and water discharge positions.

[0009] Furthermore, the spring support mechanism includes an upper cover plate, a base, and a support spring. The upper cover plate and the base are arranged correspondingly up and down. Several support springs are arranged between the upper cover plate and the base. The top ends of several support springs are connected to the bottom end of the upper cover plate, and the bottom ends of several support springs are connected to the top end of the base; a filter sleeve is provided on the outer side of the support spring to prevent sand from entering the support spring and affecting the elastic potential energy of the support spring.

[0010] Furthermore, the elastic modulus of the support spring E M The calculation formula is: ; in, is the apparent density ratio between the confined aquifer prototype and the confined aquifer simulation model; E Y is the elastic modulus of the confined aquifer prototype; C is the number of support springs.

[0011] Furthermore, an overflow prevention container is provided at the bottom of the constant pressure water column and the bottom of the constant pressure water column is placed in the overflow prevention container; the side wall of the middle part of the constant pressure water column is connected to the water inlet pipe on the pressure water bag; the calculation formula of the height h of the constant pressure water column is: ; in, P Y The magnitude of the water pressure in the prototype confined aquifer; It is the apparent density ratio between the confined aquifer prototype and the confined aquifer simulation model.

[0012] Furthermore, a loading mechanism for pressurizing the rock formation simulation material and the pressurized aquifer simulation model is provided at the top of the simulation experiment frame; the loading mechanism includes a top extrusion member, a support lever, and a bottom support member; the bottom end of the top extrusion member is placed on the top of the rock formation simulation material, the top end of the top extrusion member is connected to the middle pin shaft of the support lever, one end of the support lever is connected to a loading bucket for placing a loaded weight, and the other end of the support lever is fixedly connected to the adapter; the bottom support member is provided at the bottom end of the simulation experiment frame and supports the simulation experiment frame, and the bottom support member and the adapter are fixedly connected by a pull rod.

[0013] Furthermore, the evolution monitoring system includes a high-definition camera and scattered spots; there are several scattered spots, and the scattered spots are evenly arranged at the front end of the rock formation simulation material and the pressurized aquifer simulation model. The high-definition camera is set at the front end of the simulation experiment frame and shoots the position of the scattered spots to monitor the displacement changes of the rock formation simulation material and the pressurized aquifer simulation model through the displacement of the scattered spots.

[0014] Furthermore, the evolution monitoring system also includes a pressure box, a static strain gauge, a water pressure sensor, and a flow meter; there are several pressure boxes, and the pressure boxes are arranged at equal intervals along the height direction of the simulation experimental frame in the rock simulation material. The pressure boxes are connected to the static strain gauge and the pressure changes of all pressure boxes are monitored through the static strain gauge; the water pressure sensor is installed on the water pressure monitoring port on the pressure water bag to monitor the water pressure in the pressure water bag; the flow meter is installed on the water discharge port of the pressure water bag to monitor its water discharge flow.

[0015] A method for simulating the evolution of a device for hydrophobic stress field and deformation field of a confined aquifer comprises the following steps: S1. Laying rock formation simulation materials and a confined aquifer simulation model in a simulation test frame; during the laying process, arranging scattered spots on the front end of the inner wall of the simulation test frame and arranging a pressure box in the rock formation simulation material; S2. Arrange loading mechanisms above and below the simulation test frame, and use the loading mechanisms to pressurize the rock formation simulation material and the confined aquifer simulation model; S3, using a constant pressure water column to inject water into the pressure water bag until the water flow fills the pressure water bag; S4. Connect the static strain gauge to the pressure box; place a high-definition camera at the front end of the simulation test frame to capture the directional scattered spots; S5. Open the drain port on the pressure water bag to allow the water in the pressure water bag to flow out from the drain port; S6. Monitor the pressure change of the pressure box through a static strain gauge, monitor the displacement trajectory of the scattered spots through a high-definition camera, and monitor the water pressure and water flow in the pressure water bag through a water pressure sensor and a flow meter; S7. Obtain the evolution result of the evolution device according to the monitoring results of the static strain gauge, the high-definition camera, the water pressure sensor, and the flow meter.

[0016] The present invention combines a pressurized water bag with a spring support mechanism to ensure both the strength and elasticity of the pressurized aquifer simulation model, enabling it to withstand water pressure and simulate groundwater flow, accurately simulating the stress changes and deformation of the stratum under the action of water pressure, and providing reliable simulation results. In addition, the size and stiffness of the support spring can be adjusted according to the mechanical properties of the actual stratum to achieve a more accurate simulation effect. At the same time, the pressurized water bag is filled with sand to simulate the changing trend of the flow field during the hydrophobic process of the pressurized aquifer, thereby achieving an accurate fluid-solid coupling simulation effect. The particle size, density and permeability of the sand can be adjusted according to geological conditions to ensure that the physical properties of the simulated stratum are consistent with the actual one, thereby enhancing the authenticity of the simulation. On the other hand, the present invention uses a constant-pressure water column to supply water to the pressurized water bag, effectively solving the problem that the aquifer cannot be laterally replenished at constant pressure in similar simulated dynamic tests; at the same time, the present invention uses an evolution monitoring system to monitor the water pressure, stress field transfer and rock formation displacement deformation in real time during the hydrophobic process, and finally obtains the changing trend of the aquifer flow field under hydrophobic conditions, as well as the changing laws of the stress field and displacement field of the surrounding rock formations.

[0017] Compared with traditional simulation technology, the confined aquifer simulation model in the present invention can simultaneously consider the influence of fluid dynamics and solid mechanics, thereby providing a more comprehensive simulation environment; based on this device, the evolution of the aquifer's hydrophobic flow field, stress field transfer, and displacement field changes are simulated, providing data and theoretical support for field experiments, effectively reducing the uncertainty and workload of field experiments; this evolution operation can more comprehensively understand the impact of coal seam mining on the stratum structure and hydrogeological conditions, and provide a certain scientific basis for preventing and controlling mine water inrush accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Schematic diagram of the structure of the evolution device; Figure 2 is a structural diagram of the loading mechanism; Figure 3 This is the rear view structure diagram of the confined aquifer simulation model; Figure 4 This is the main structural diagram of the confined aquifer simulation model; Figure 5 This is a partial cross-sectional view of the confined aquifer simulation model; Figure 6 Schematic diagram of the structure of the spring support mechanism; Figure 7 This is the installation structure diagram of the pressure box. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts, any modifications, equivalent replacements, improvements, etc., shall be included in the scope of protection of the present invention.

[0021] like Figures 1 to 7As shown, this embodiment discloses a device for simulating the evolution of stress field and deformation field of hydrophobicity in a confined aquifer, including a simulation experiment frame 1, which is a shell structure with an open top; the simulation experiment frame 1 is filled with rock formation simulation material 2, and a confined aquifer simulation model 3 is arranged in the rock formation simulation material 2, and the confined aquifer simulation model 3 is connected to a constant pressure water column 5 pipeline arranged on the outside of the simulation experiment frame 1 and provides water pressure to the confined aquifer simulation model 3 through the constant pressure water column 5; the simulation experiment frame 1 is provided with an evolution monitoring system, and the evolution monitoring system is used to monitor the stress changes and displacement changes caused to the rock formation simulation material 2 by hydrophobicity of the confined aquifer simulation model 3 in the simulation experiment frame 1.

[0022] The simulation experiment frame 1 is a cubic metal frame structure, consisting of a bottom baffle, a top baffle, and two side baffles. The bottom baffle is connected to the bottom of the side baffles, and the top baffle is connected to the top of the side baffles. The front of the simulation experiment frame is sequentially mounted from the bottom to the top, with the ends of each front baffle connected to the corresponding side baffle. Similarly, the back of the simulation experiment frame is also sequentially mounted from the bottom to the top, with the ends of each rear baffle also connected to the side baffles.

[0023] The rock formation simulation material 2 includes bottom plate simulation material, coal seam simulation material, roof plate simulation material, and overlying rock formation simulation material. The bottom plate simulation material, coal seam simulation material, roof plate simulation material, and overlying rock formation simulation material are all made by mixing sand, lime, gypsum, and water in proportion; the bottom plate simulation material, coal seam simulation material, roof plate simulation material, pressurized aquifer simulation model, and overlying rock formation simulation material are layered and laid in sequence from bottom to top in the simulation experimental frame; the bottom plate simulation material, coal seam simulation material, roof plate simulation material, and overlying rock formation simulation material are all formed by stacking and laying several layers of materials in sequence, and the thickness of each layer of material is 20 mm.

[0024] Rock strata simulation materials are similar to actual strata and consist of a mixture of sand, lime, gypsum, and water in specific proportions. Specifically, the ratios of sand, lime, gypsum, and water used in the floor, coal seam, roof, and overlying strata are precisely blended based on the mechanical strength characteristics of the actual strata and the strength scaling of the model.

[0025] Geometric similarity requires that the geometric shape of the test model is similar to that of the on-site prototype. Therefore, the dimensions of the on-site prototype, including length, width, and height, need to be reduced in a certain proportion to make the test model. and Represent the length of the prototype and model respectively, is the length scale, is a constant, then the geometric similarity requirement is: ; The geometric similarity ratio is generally 1 / (100~200).

[0026] Apparent density scale: ; 、 Represent the apparent density of the corresponding parts of the prototype and model respectively.

[0027] Strength scale: ; The stress similarity ratio is generally 167 to 334.

[0028] In the above-mentioned evolution device, the similar materials in the bottom plate, the coal seam, the thin bedrock layer and the thick topsoil layer are laid in layers from bottom to top in the simulation experimental frame. The thickness of each layer of the similar materials is 20 mm, and mica powder is laid between two adjacent layers of the similar materials.

[0029] The confined aquifer simulation model 3 includes a confined water bag 31 and a spring support mechanism 32. Several spring support mechanisms 32 are arranged side by side in the confined water bag 31, and the interior of the confined water bag 31 is supported by the spring support mechanism 32. The confined water bag 31 is filled with sand 33, and the sand 33 is located in the gap between the spring support mechanism 32 and the inner wall of the confined water bag 31. The sand is river sand of a specific particle size. Water inlets 311 are provided at both ends of the back of the confined water bag 31 and are connected to the constant pressure water column 5 pipeline through the water inlets 311. A water discharge port 313 is provided in the middle of the front of the confined water bag 31. Control valves are provided at the positions of the water inlet 311 and the water discharge port 313.

[0030] The pressure water bag 31 is made of PVC mesh cloth, which ensures both strength and elasticity, enabling it to withstand water pressure and simulate groundwater flow, accurately replicating the state of the aquifer on site; The spring support mechanism 32 includes an upper cover plate 322, a base 321, and a support spring 323. The upper cover plate 322 and the base 321 are arranged correspondingly up and down. Two support springs 323 are arranged between the upper cover plate 322 and the base 321. The top ends of the two support springs 323 are connected to the bottom end of the upper cover plate 322, and the bottom ends of the two support springs 323 are connected to the top end of the base 321; a filter sleeve 34 is provided on the outside of the support spring 323 to prevent sand 33 from entering the support spring 323 and affecting the elastic potential energy of the support spring 323.

[0031] The upper cover and base are I-beam structures. I-beams are selected as the skeleton material due to their high strength and stability, while the springs provide the necessary elasticity, thereby simulating the stress changes and deformation of the stratum under water pressure. The support springs are connected to the upper cover and base to form a whole, providing vertical support for the pressure water bag, ensuring that the water bag can maintain its structural integrity and functionality when under pressure.

[0032] The interior of the pressure water bag is supported by springs and I-steels. Different working conditions can be achieved by adjusting the elastic modulus of the springs. The elastic modulus EM of the springs is calculated based on the elastic modulus EY of the on-site aquifer, the apparent density scale, and the number of springs C: ; The constant pressure water column 5 is a constant head water column, and the water pressure is stable by water delivery. The bottom of the constant pressure water column 5 is provided with an overflow prevention container 6 and the bottom of the constant pressure water column 5 is placed in the overflow prevention container 6; the middle side wall of the constant pressure water column 5 is connected to the water inlet pipeline on the pressure water bag 31; the calculation formula of the height h of the constant pressure water column 5 is: ; in, P Y The water pressure of the prototype confined aquifer; is the apparent density ratio between the confined aquifer prototype and the confined aquifer simulation model; The simulation test frame 1 cannot completely simulate the overlying rock layer above the coal seam, so the model uses physical pressurization to supplement the missing pressure; The top of the simulation experiment frame 1 is provided with a loading mechanism for pressurizing the rock formation simulation material 2 and the pressurized aquifer simulation model 3; the loading mechanism includes a top extrusion member 7, a support lever 9, and a bottom support member 10; the bottom end of the top extrusion member 7 is placed on the top of the rock formation simulation material 2, and the top of the top extrusion member 7 is connected to the middle pin of the support lever 9. One end of the support lever 9 is connected to a loading bucket 12 for placing a loaded weight, and the other end of the support lever 9 is fixedly connected to the adapter 8. The distance from the lever fulcrum to the loading point: the total length of the lever = 1:10; the bottom support member 10 is provided at the bottom end of the simulation experiment frame 1 and supports the simulation experiment frame 1. The bottom support member 10 and the adapter 8 are fixedly connected by a pull rod 11.

[0033] By placing a loading weight in the loading barrel, the other end of the support lever and the adapter, pulling member, and bottom support member can jointly exert an upward force. This force cooperates with the top extrusion member to give the rock simulation material in the simulation experiment frame an extrusion pressure. This extrusion pressure can make up for the pressure that is lacking when the model is conducting a simulation experiment, so as to improve the simulation authenticity.

[0034] The evolution monitoring system includes a displacement monitoring system and a stress monitoring system. The displacement monitoring system includes several surface monitoring spots 4, evenly spaced on the front surface of the simulated stratum, with 10 cm spacing between each two spots. A high-precision digital camera is also equipped to accurately capture the surface monitoring points and lines of the simulated stratum. This camera can monitor the displacement and deformation of the stratum in real time and analyze soil collapse and crack propagation, providing key data for stratum stability assessment and geological disaster prediction.

[0035] In this displacement monitoring system, speckles are divided into two categories: reference points and common speckles. The displacement monitoring system uses the reference points to precisely locate the common speckles and, by comparing the speckle images captured by the camera, analyzes the displacement changes at each monitoring point during the drainage process. This process enables us to accurately assess the specific impact of drainage on rock formation deformation.

[0036] The stress monitoring system includes a pressure cell 13 and a static strain gauge 14. A plurality of pressure cells 13 are evenly arranged in the simulated formation and are connected to the static strain gauge 14 to monitor the pressure data in the simulated formation in real time. The pressure water bag 31 is provided with ten water pressure monitoring ports 312, each equipped with a water pressure sensor. A filter screen is installed between the water pressure sensor and the pressure water bag 31 to prevent the sand-water mixture from contaminating the sensor interface. The water pressure sensor is a HY-P300 water pressure sensor, and a TP700 data acquisition device is used to collect data in real time. The water pressure sensor configuration enables real-time monitoring and recording of the water pressure at various points within the pressure aquifer simulation model.

[0037] A flow meter and a valve are installed on the discharge port 313 of the pressure water bag 31. The flow meter monitors and records the instantaneous flow rate and total flow rate of the drainage in real time, and the outlet can simulate the influence of drainage on the flow field of the aquifer and the stress and strain of the surrounding rock formations under different drainage speed conditions by adjusting the size of the valve opening; the water valve is used to adjust the drainage rate during the drainage process, and the water pressure and flow are monitored in real time using a water pressure sensor and a flow meter.

[0038] This embodiment also discloses an evolution method of the above-mentioned evolution device, comprising the following steps: S1. Laying rock formation simulation material 2 and confined aquifer simulation model 3 in a simulation test frame 1; during the model construction process, laying a plastic film on the upper portion of the confined aquifer simulation model where it contacts similar simulation materials to prevent the rock formation simulation material from overflowing during the laying process or pressurization process on the upper portion of the confined aquifer simulation model; during the laying process, scatter spots are arranged on the front end of the inner wall of the simulation test frame, and a pressure cell is arranged inside the rock formation simulation material; S2. Arrange a loading mechanism above and at the bottom of the simulation test frame 1, and use the loading mechanism to pressurize the rock formation simulation material and the confined aquifer simulation model; S3, using the constant pressure water column 5 to inject water into the pressure water bag 31 until the water flow fills the pressure water bag 31; S4, connecting the static strain gauge 14 to the pressure box 13; placing a high-definition camera at the front end of the simulation experimental frame 1 to shoot the scattered spots 4; S5. Open the drain port 313 on the pressure water bag 31 to allow the water in the pressure water bag 31 to flow out from the drain port 313. S6. Monitor the pressure change of the pressure box 13 through the static strain gauge 14, monitor the displacement trajectory of the scattered spots 4 through the high-definition camera, and monitor the water pressure and water flow in the pressure water bag 31 through the water pressure sensor and flow meter; S7. The evolution monitoring system performs water pressure detection, flow monitoring, displacement monitoring, and stress monitoring on the model, and ultimately obtains the change trend of the aquifer flow field under hydrophobic conditions, as well as the change laws of the stress field and displacement field of the surrounding rock formations.

[0039] The present invention combines a pressurized water bag with a spring support mechanism to ensure both the strength and elasticity of the pressurized aquifer simulation model, enabling it to withstand water pressure and simulate groundwater flow, accurately simulating the stress changes and deformation of the stratum under the action of water pressure, and providing reliable simulation results. In addition, the size and stiffness of the support spring can be adjusted according to the mechanical properties of the actual stratum to achieve a more accurate simulation effect. At the same time, the pressurized water bag is filled with sand to simulate the changing trend of the flow field during the hydrophobic process of the pressurized aquifer, thereby achieving an accurate fluid-solid coupling simulation effect. The particle size, density and permeability of the sand can be adjusted according to geological conditions to ensure that the physical properties of the simulated stratum are consistent with the actual one, thereby enhancing the authenticity of the simulation. On the other hand, the present invention uses a constant-pressure water column to supply water to the pressurized water bag, effectively solving the problem that the aquifer cannot be laterally replenished at constant pressure in similar simulated dynamic tests; at the same time, the present invention uses an evolution monitoring system to monitor the water pressure, stress field transfer and rock formation displacement deformation in real time during the hydrophobic process, and finally obtains the changing trend of the aquifer flow field under hydrophobic conditions, as well as the changing laws of the stress field and displacement field of the surrounding rock formations.

[0040] Compared with traditional simulation technology, the confined aquifer simulation model in the present invention can simultaneously consider the influence of fluid dynamics and solid mechanics, thereby providing a more comprehensive simulation environment; based on this device, the evolution of the aquifer's hydrophobic flow field, stress field transfer, and displacement field changes are simulated, providing data and theoretical support for field experiments, effectively reducing the uncertainty and workload of field experiments; this evolution operation can more comprehensively understand the impact of coal seam mining on the stratum structure and hydrogeological conditions, and provide a certain scientific basis for preventing and controlling mine water inrush accidents.

Claims

1. A device for simulating the evolution of hydrophobic stress and deformation fields in a confined aquifer, comprising a simulation test frame, characterized in that: The simulation experiment frame is a shell structure with an open top; the simulation experiment frame is filled with rock formation simulation material, and a confined aquifer simulation model is arranged in the rock formation simulation material. The confined aquifer simulation model is connected to a constant pressure water column pipeline arranged on the outside of the simulation experiment frame, and the constant pressure water column provides water pressure to the confined aquifer simulation model; the simulation experiment frame is provided with an evolution monitoring system, and the evolution monitoring system is used to monitor the stress and displacement changes caused by the rock formation simulation material when the confined aquifer simulation model in the simulation experiment frame is drained; the confined aquifer simulation model is scaled down based on the on-site prototype; set up is the length of the on-site prototype, is the length of the confined aquifer simulation model, is the length scale, then the geometric similarity requirement between the confined aquifer simulation model and the field prototype is ; Apparent density scale is ; Strength scale is ;in 、 Represent the apparent density of the corresponding parts of the prototype and model respectively.

2. The device for simulating the evolution of hydrophobic stress and deformation fields in a confined aquifer according to claim 1, characterized in that: The rock formation simulation material includes bottom plate simulation material, coal seam simulation material, roof plate simulation material, and overlying rock formation simulation material. The bottom plate simulation material, coal seam simulation material, roof plate simulation material, and overlying rock formation simulation material are all made by mixing sand, lime, gypsum, and water in proportion; the bottom plate simulation material, coal seam simulation material, roof plate simulation material, pressurized aquifer simulation model, and overlying rock formation simulation material are laid in layers from bottom to top in the simulation experimental frame.

3. The device for simulating the evolution of hydrophobic stress field and deformation field of a confined aquifer according to claim 2, characterized in that: The confined aquifer simulation model includes a confined water bag and a spring support mechanism. Several spring support mechanisms are arranged side by side in the confined water bag, and the interior of the confined water bag is supported by the spring support mechanism. The confined water bag is filled with sand, and the sand is located in the gap between the spring support mechanism and the inner wall of the confined water bag. Both ends of the confined water bag are provided with water inlets, which are connected to the constant pressure water column pipeline through the water inlets. A water discharge port is provided in the middle of the confined water bag. Control valves are provided at the water inlet and the water discharge port.

4. The device for simulating the evolution of hydrophobic stress and deformation fields in a confined aquifer according to claim 3, characterized in that: The spring support mechanism includes an upper cover plate, a base, and a support spring. The upper cover plate and the base are arranged correspondingly up and down. Several support springs are arranged between the upper cover plate and the base. The top ends of several support springs are connected to the bottom end of the upper cover plate, and the bottom ends of several support springs are connected to the top end of the base. A filter sleeve is provided on the outer side of the support spring to prevent sand from entering the support spring and affecting the elastic potential energy of the support spring.

5. The device for simulating the evolution of hydrophobic stress field and deformation field of a confined aquifer according to claim 4, characterized in that: Elastic modulus of the support spring E M The calculation formula is: ； in, is the apparent density ratio between the confined aquifer prototype and the confined aquifer simulation model; E Y is the elastic modulus of the confined aquifer prototype; C is the number of support springs.

6. The device for simulating the evolution of hydrophobic stress field and deformation field of a confined aquifer according to claim 5, characterized in that: The bottom of the constant pressure water column is provided with an overflow prevention container and the bottom of the constant pressure water column is placed in the overflow prevention container; the middle side wall of the constant pressure water column is connected to the water inlet pipe on the pressure water bag; the calculation formula of the height h of the constant pressure water column is: ； in, P Y The magnitude of the water pressure in the prototype confined aquifer; It is the apparent density ratio between the confined aquifer prototype and the confined aquifer simulation model.

7. The device for simulating the evolution of hydrophobic stress field and deformation field of a confined aquifer according to claim 6, characterized in that: A loading mechanism for pressurizing the rock formation simulation material and the confined aquifer simulation model is provided at the top of the simulation experiment frame; the loading mechanism includes a top extrusion member, a support lever, and a bottom support member; the bottom end of the top extrusion member is placed on the top of the rock formation simulation material, the top end of the top extrusion member is connected to the pin shaft in the middle of the support lever, one end of the support lever is connected to a loading bucket for placing a loaded weight, and the other end of the support lever is fixedly connected to the adapter; the bottom support member is provided at the bottom end of the simulation experiment frame and supports the simulation experiment frame, and the bottom support member and the adapter are fixedly connected by a pull rod.

8. The device for simulating the evolution of hydrophobic stress field and deformation field of a confined aquifer according to claim 7, characterized in that: The evolution monitoring system includes a high-definition camera and scattered speckles; there are a plurality of scattered speckles, and the scattered speckles are evenly arranged at the front end of the rock formation simulation material and the pressurized aquifer simulation model. The high-definition camera is set at the front end of the simulation experiment frame and photographs the position of the scattered speckles to monitor the displacement changes of the rock formation simulation material and the pressurized aquifer simulation model through the displacement of the scattered speckles.

9. The device for simulating the evolution of hydrophobic stress field and deformation field of a confined aquifer according to claim 8, characterized in that: The evolution monitoring system also includes a pressure cell, a static strain gauge, a water pressure sensor, and a flow meter; there are multiple pressure cells, which are evenly spaced along the height direction of the simulation test frame within the rock formation simulation material. The pressure cells are connected to the static strain gauge and the pressure changes of all the pressure cells are monitored through the static strain gauge; the water pressure sensor is installed on the water pressure monitoring port on the pressure water bag to monitor the water pressure within the pressure water bag; The flow meter is installed on the water discharge port of the pressure water bag to monitor the water discharge flow rate.

10. An evolution method of the device for simulating the evolution of hydrophobic stress field and deformation field of a confined aquifer according to claim 9, characterized in that: The following steps are involved: S1. Laying rock formation simulation materials and a confined aquifer simulation model in a simulation test frame; during the laying process, arranging scattered spots on the front end of the inner wall of the simulation test frame and arranging a pressure box in the rock formation simulation material; S2. Arrange loading mechanisms above and below the simulation test frame, and use the loading mechanisms to pressurize the rock formation simulation material and the confined aquifer simulation model; S3, using a constant pressure water column to inject water into the pressure water bag until the water flow fills the pressure water bag; S4. Connect the static strain gauge to the pressure box; place a high-definition camera at the front end of the simulation test frame to capture the directional scattered spots; S5. Open the drain port on the pressure water bag to allow the water in the pressure water bag to flow out from the drain port; S6. Monitor the pressure change of the pressure box through a static strain gauge, monitor the displacement trajectory of the scattered spots through a high-definition camera, and monitor the water pressure and water flow in the pressure water bag through a water pressure sensor and a flow meter; S7. Obtain the evolution result of the evolution device according to the monitoring results of the static strain gauge, the high-definition camera, the water pressure sensor, and the flow meter.

Images