Device and method for testing mining-induced stress-seepage characteristics of modified rock

Abstract

The invention belongs to the technical field of grouting tests, and particularly discloses a modified rock mining-induced stress-seepage characteristic test device and method, and the device comprises a core holder, a grouting system, a confining pressure system, a back pressure system, an oil-water separation system, a stress switching system and a data acquisition system. The core holder can independently adjust axial pressure, confining pressure and pore water pressure; the grouting system injects grout through a constant-flux pump and a piston container; and the oil-water separation system is provided with a sapphire window and a camera monitor, so that the groutability of the rock can be quantitatively represented. The test method comprises the steps of simulation of a primary rock stress environment, a grouting modification test, a mining-induced stress-seepage characteristic test and the like, the dynamic change of the mining-induced stress environment is simulated through the stress switching system, and parameters of a stress field and a seepage field are monitored in real time. According to the invention, accurate separation of multi-phase fluid and full-period stress-seepage dynamic simulation of mining under primary rock stress are realized, and accurate test support is provided for a water-preserved coal mining technology.

Description

Technical Field

[0001] The present invention relates to the technical field of grouting tests, and particularly to an experimental device and method for the mining-induced stress-seepage characteristics of modified rocks. Background Technique

[0002] Grouting modification of roof and floor rock strata is an important supporting technology for water-preserved coal mining. Its core lies in enhancing the mechanical properties of rocks and reducing the rock permeability coefficient through grouting technology, so as to improve the comprehensive anti-deformation and anti-seepage ability of rocks under mining-induced stress-seepage, and then achieve the goal of water-preserved coal mining. Determining the pre-mining grouting modification parameters, quantifying the injectability of rocks, and the effect of in-situ rock modification during mining are of top priority. The invention patents with publication numbers CN111595755B and CN106908365B have both proposed relevant seepage test devices and methods, and many related studies have also been carried out in the prior art.

[0003] The above research provides a reference for the research of the present invention, but there are still the following deficiencies: The existing test devices mainly exist independently as the pre-mining stress-hydraulic rock grouting test system and the mining-induced modified rock stress-hydraulic test system, and cannot restore the complex environment of the changing stress field-hydraulic field-high-pressure grout field of the roof and floor before and during mining. Moreover, there are large errors in characterizing the injectability of rocks, and there is a lack of a test system and method for the non-destructive transformation of the original rock stress of the roof and floor into mining-induced stress after rock modification, which poses great challenges to the determination of roof and floor grouting parameters, the quantification of rock injectability, and the evaluation of the effect of mining-induced rock modification. Specifically as follows:

[0004] 1. The slurry is compatible with the pore water of the rock and is difficult to distinguish, resulting in large errors in characterizing the injectability of the rock: Since organic slurries have poor anti-deformation ability and there is a risk of polluting groundwater, the existing roof and floor grouting materials are mainly inorganic. However, the existing grouting test devices are based on the basic assumption that the slurry completely replaces the pore water in terms of the indicators for characterizing the injectability of rocks. However, during the slurry diffusion process, the inorganic slurry will inevitably mix with the pore water. Due to the general lack of effective and accurate separation devices and methods in traditional test devices, it is difficult to effectively separate the slurry from the rock pore water, which will lead to the distortion of the quantification results of rock injectability and directly affect the evaluation of rock injectability, the development of grouting materials, and the determination of grouting parameters.

[0005] 2. Existing test devices mainly exist independently as the pre-mining stress - hydraulic rock grouting test system and the mining - modified rock stress - hydraulic test system, and are unable to restore the complex and multi - field environment of the stress field - hydraulic field - high - pressure slurry field during pre - mining and mining in the roof and floor. The traditional test system needs to disassemble the device and take cores after grouting to carry out the stress - seepage characteristics of the modified rock. There are high - cost problems in borehole pressure relief and maintaining rock stress - pore water pressure. Therefore, it is difficult to provide support for the analysis of the stress - seepage characteristics of the fully - cycled modified rock during the sequential transformation of the in - situ stress area in the modified target area of the roof and floor to the mining stress environment.

[0006] 3. The accuracy of multi - parameter coupling control is insufficient: There are technical bottlenecks in the coordinated control of axial pressure, confining pressure, pore water pressure, and grouting pressure in existing devices. For example, it is difficult for the manually adjusted confining pressure pump to achieve high - precision pressure closed - loop control, and the insufficient flow stability of the peristaltic pump (±0.1 mL / min error) may cause fluctuations in the grouting rate, which in turn affects the uniformity of slurry diffusion.

[0007] In summary, there is an urgent need for an integrated test device and method that can achieve precise separation of the slurry - water two - phase fluid under stress - hydraulic conditions and non - destructive testing of the stress - seepage characteristics of the rock after full - cycle modification from pre - mining to mining, so as to break through the existing technical bottlenecks and provide hardware and method support for quantifying the injectability of rocks, determining the grouting parameters of the roof and floor, and evaluating the effect of mining - induced rock modification. Summary of the Invention

[0008] The purpose of the present invention is to provide a test device and method for the stress - seepage characteristics of mining - modified rocks to solve the above - mentioned technical problems existing in the prior art.

[0009] To achieve the above purpose, in one aspect, the present invention provides a test device for the stress - seepage characteristics of mining - modified rocks, including:

[0010] A core holder for fixing the core and applying axial pressure, confining pressure, and pore water pressure;

[0011] A grouting system including a peristaltic pump and a piston container I connected to one end of the core holder;

[0012] A confining pressure system including a pump I connected to the periphery and the end of the core holder, and the pump I is used to apply annular pressure and axial pressure to the core holder;

[0013] A back - pressure system including a pump II, a back - pressure valve, and a back - pressure buffer container connected to one end of the core holder;

[0014] An oil - water separation system including an oil - water separator provided between the back - pressure system and the core holder;

[0015] A stress switching system, including a piston container II connected to one end of a core holder, and the piston container II is connected to the peristaltic pump;

[0016] A data acquisition system, including an inlet pressure monitor and an outlet pressure monitor provided at both ends of the core holder, and a surrounding rock pressure monitor provided on the periphery of the core holder.

[0017] Optionally, the axial pressure, confining pressure and pore water pressure of the core holder are independently adjustable, and the maximum loading pressure is 30 MPa for all.

[0018] Optionally, the pressure range of the peristaltic pump is 0 - 30 MPa, and the flow accuracy is ±0.1 mL / min.

[0019] Optionally, the pressure regulation accuracy of the back pressure system is 0.01 MPa.

[0020] Optionally, the oil-water separator is equipped with a sapphire window, with a measuring range of 50 mL and a pressure resistance of 30 MPa.

[0021] Optionally, the oil-water separator analyzes the slurry proportion through the cooperation of a camera monitor and a sapphire window.

[0022] Optionally, the modified rock mining stress-seepage characteristic test device further includes a visual measurement system, and the visual measurement system includes a sapphire window configured on the oil-water separator and a camera monitor facing the sapphire window.

[0023] Optionally, the piston container II and the piston container I are respectively provided at both ends of the core holder, and are used to simulate the dynamic infiltration of pore water under mining stress.

[0024] On the other hand, the present invention also provides a method for testing the mining stress-seepage characteristics of modified rock. According to the modified rock mining stress-seepage characteristic test device described in any one of the above, the test method includes the following steps:

[0025] Step S1: Preparation before the test, including device assembly and core installation;

[0026] Step S2: Simulate the original rock stress environment, and apply pore water pressure, confining pressure and axial pressure;

[0027] Step S3: Start the grouting system, inject the slurry at a set pressure and flow rate, and quantitatively analyze the slurry proportion through the oil-water separator;

[0028] Step S4: Switch the stress system to simulate the dynamic change of mining stress, and monitor the seepage parameters in real time and generate a stress-seepage coupling curve;

[0029] Step S5: Terminate the test, integrate the data and evaluate the injectability of grouting and the seepage characteristics under mining stress.

[0030] In an alternative embodiment, in step S4, the seepage characteristics under the condition of dynamic change of mining-induced stress are simulated by switching the piston container II and adjusting the confining pressure and axial pressure.

[0031] The present invention discloses the following technical effects:

[0032] Through the synergistic effect of the core clamping system, grouting system, oil-water separation module, stress switching system and back pressure control system, and by using the oil-water separation technology and visual quantitative analysis, the present invention solves the problem of difficult distinction between grout and pore water, realizes the quantitative characterization of rock injectability, realizes the non-destructive transformation of in-situ stress to mining-induced stress through the stress switching system, realizes the evaluation of the rock modification effect before and during the mining period, and provides accurate experimental support for the water-preserved coal mining technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 It is a schematic structural diagram of the test device of the present invention;

[0035] Figure 2 It is a flow chart of the test method of the present invention.

[0036] In the figure: 1. Back pressure system; 2. Confining pressure system; 3. Grouting system; 4. Peristaltic pump; 5. Piston container I; 6. Outlet pressure monitor; 7. Core holder; 8. Surrounding rock pressure monitor; 9. Pump I; 10. Oil tank I; 11. Inlet pressure monitor; 12. Oil-water separator; 13. Camera monitor; 14. Piston container II; 15. Back pressure valve; 16. Back pressure buffer container; 17. Pressure sensor; 18. Pump II; 19. Oil tank II. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0038] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0039] Example 1

[0040] Reference Figure 1 As shown, Example 1 of the present invention provides a test device for the modified rock mining stress-seepage characteristics, including a core holder 7, a grouting system 3, a backpressure system 1, an oil-water separation system, a stress switching system, a visual measurement system, and a data acquisition system.

[0041] In the embodiment of the present invention, the core holder 7 is used to fix the core and apply axial pressure, confining pressure, and pore water pressure. Its function is to ensure that the core is firmly fixed during the experiment, avoid displacement, and thus ensure the accuracy of the experiment. Its working principle is: the core holder 7 clamps and fixes the core through mechanical equipment to provide stable support to ensure that the pressure and fluid flow during the grouting process are not affected by the instability of the core.

[0042] In a specific embodiment, the applied axial pressure range is 0 - 30 MPa, the confining pressure range is 0 - 30 MPa, and the pore water pressure range is 0 - 8 MPa.

[0043] In a specific embodiment, the material of the core holder 7 is mainly 304 steel, the size specification is a diameter of 50 mm and a height of 100 mm, the working pressure is 30 MPa, and the working temperature is room temperature.

[0044] In the embodiment of the present invention, the grouting system 3 includes a metering pump 4 and a piston container I 5. The piston container I 5 is connected to the inlet and outlet of the core holder 7, and an inlet pressure monitor 11 is provided on the inlet pipeline, and an outlet pressure monitor 6 is provided on the outlet pipeline. The grouting system 3 is used to apply grouting pressure to the core holder 7 to achieve precise control of the grouting pressure and rate through the metering pump 4 and the piston container I 5.

[0045] The metering pump 4 provides stable fluid flow to simulate the penetration process of water flow or slurry in the core. It ensures the continuous flow of the liquid by controlling the flow rate and pressure to maintain stable flow conditions in the system. The metering pump 4 can adjust the flow rate and velocity and is suitable for experiments that require long-term stable liquid delivery.

[0046] The piston container I 5 includes a container body and a piston body that moves in the container body in a piston manner. The piston container I 5 is used to store the slurry and apply pressure to simulate the injection process of the slurry in the rock. Its working principle is: the piston body applies pressure to the slurry in the container body through mechanical means to help simulate the pressure change during the actual grouting process.

[0047] In a specific embodiment, the pressure range of the advection pump 4 is 0 - 30 MPa, and the flow rate is 0.1 - 50 mL / min; the volume of the first piston container 5 is 500 mL, the pressure resistance is 50 MPa, and the material of the container body is 304 stainless steel.

[0048] In the embodiment of the present invention, the confining pressure system 2 includes a first pump 9 and a surrounding rock pressure monitor 8, which are used to apply annular pressure and axial pressure to the core holder 7.

[0049] The first pump 9 is connected to the first oil tank 10. The first pump 9 can be selected as a SYB-2 type manual metering pump with a pump chamber of 60 mL. The SYB-2 type manual metering pump is usually used in a small-scale, manually controlled experimental environment. It mainly provides fluid pressure or flow rate through manual operation. It can adjust the fluid flow in the initial stage or local area of the experiment. Especially in the case where rapid adjustment or pressure experiment is required, it can quickly and accurately control the flow of the liquid.

[0050] The surrounding rock pressure monitor 8 can adopt the same type of pressure monitoring device as the inlet pressure monitor 11 and the outlet pressure monitor 6. The inlet pressure monitor 11, the outlet pressure monitor 6, and the surrounding rock pressure monitor 8 continuously monitor the inlet of the core holder 7, the outlet of the core holder 7, and the pressure of the surrounding rock pressure liquid respectively. By feeding back the pressure data, the experimenter can understand the pressure change of the liquid at the outlet in real time, so as to judge the liquid flow state in the experiment. In the grouting or seepage experiment, the pressure of the liquid flow must be kept within the set range to ensure the stability of the experiment. If the pressure is too high or too low, it may lead to inaccurate experimental results or system instability.

[0051] In the embodiment of the present invention, the backpressure system 1 includes a backpressure valve 15, a backpressure buffer container 16, a pressure sensor 17, and a second pump 18. The second pump 18 is connected to the second oil tank 19. The backpressure system 1 is used to provide pore water pressure to the core holder 7. After the inlet pressure reaches the set value of the pore pressure, the advection pump 4 is stopped, and the pressure is maintained through the backpressure valve 15.

[0052] The first oil tank 10 and the second oil tank 19 in the embodiment of the present invention are both used to store hydraulic oil and provide hydraulic power for the hand-operated hydraulic pumps (the first pump 9 and the second pump 18). When the hand-operated hydraulic pumps work, they will extract hydraulic oil from the oil tank and apply pressure through the hydraulic system to ensure that there is enough hydraulic oil supply in the experimental system to meet the need of applying confining pressure or pore water pressure during the experiment.

[0053] The backpressure valve 15 is used to control the pressure in the reflux system, ensure that the slurry can withstand the preset pressure during the injection process, and can adjust the reflux through the control system. Its working principle is to adjust the pressure in the reflux pipeline according to the instructions of the control system to ensure that the pressure is kept within a safe range.

[0054] The second pump 18 can be selected as a SYB-2 type manual metering pump, using the same model as the first pump 9. The function of the second pump 18 is to provide an initial pressure for the core and simulate the pore water pressure in the underground rock formation. The pore water pressure applied to the core is adjusted by manually adjusting the second pump 18.

[0055] The pressure sensor 17 is equipped with an AI-5 series liquid crystal display instrument.

[0056] In the embodiment of the present invention, the oil-water separation system includes an oil-water separator 12. The oil-water separator 12 is used to separate the oil and pore water in the slurry. By utilizing the characteristic that oil and water are immiscible, it helps to clearly distinguish oil and water, facilitating subsequent analysis. The oil-water separator 12 separates oil and water through a physical separation method, and the separated oil and water can be further measured and recorded by a visualization quantitative reading device.

[0057] The pore water in the original porous medium is separated from the injected slurry by the oil-water separator 12. The proportion of the slurry and the separation effect of oil and water can be quantitatively measured, thereby judging the grouting effect. Through the oil-water separation device, the proportion of the slurry at different time periods can be quantitatively read, the relative proportion of the slurry and oil can be analyzed, and the data is input into the experimental system to form an experimental data record.

[0058] In the embodiment of the present invention, the stress switching system is a second piston container 14 arranged between the backpressure system 1 and the core holder 7. The second piston container 14 and the first piston container 5 are respectively arranged at both ends of the core holder 7 and are used to simulate the dynamic change of mining stress. The second piston container 14 can adopt the same structure as the first piston container 5, including a container body and a piston body that moves in the container body in a piston-like manner. The container body is used to store pore water to simulate the infiltration of pore water in the rock.

[0059] In the embodiment of the present invention, the visual metering system includes a sapphire window configured on the oil-water separator 12, a camera monitor 13, and a dedicated analysis module. Among them, the range of the sapphire window is 50 mL, and the accuracy is ±0.1 mL; the camera monitor 13 can adopt a CCD camera and is equipped with a dedicated light source. The proportion of the slurry is quantitatively analyzed through the sapphire window and the CCD camera.

[0060] In the embodiment of the present invention, the data acquisition system includes the above-mentioned inlet pressure monitor 11, outlet pressure monitor 6, surrounding rock pressure monitor 8, and electronic balance. Among them, the accuracy of the surrounding rock pressure monitor 8 is 0.25% F.S., the range of the electronic balance is 2200 g, and the accuracy is 10 mg. The test data is recorded in real time through the inlet pressure monitor 11, outlet pressure monitor 6, surrounding rock pressure monitor 8, and electronic balance.

[0061] It should be understood that in practical applications, the embodiments of the present invention further include auxiliary accessories, including pipe valve parts, experimental platform brackets, control chassis, electrical circuit integration, data analysis software, etc. The above-mentioned auxiliary accessories all adopt mature products in the art and will not be elaborated here.

[0062] Embodiment 2

[0063] Referring to Figure 2 As shown, Embodiment 2 of the present invention provides a test method for the mining stress-seepage characteristics of modified rock, using the test device for the mining stress-seepage characteristics of modified rock described in Embodiment 1. The test method includes the following steps:

[0064] Step S1. Preparation before the test, including:

[0065] Step S11. Device assembly: Connect the system components of the test device, check the connection correctness and pipeline tightness to ensure the closure and functionality of the fluid system;

[0066] Step S12. Core installation: Take a core of appropriate size (in this embodiment, the diameter of the core is 50 mm and the height is 100 mm), and place the core into the core holder 7 to ensure stable fixation of the core.

[0067] Step S2. Simulation of the in-situ stress environment, including:

[0068] Step S21. Apply pore water pressure: Start pump two 18, inject pore water (or replace it with an oil phase) into the core holder 7 to simulate the pore water pressure in the underground rock formation;

[0069] Monitor the pressure in real time through the inlet pressure monitor 11, and adjust the flow rate of pump two 18 until the inlet pressure of the core holder 7 reaches a predetermined value, which is set according to the test requirements;

[0070] When the inlet pressure reaches the predetermined value, stop the operation of pump two 18 and use the back pressure valve 15 to maintain the pressure;

[0071] Step S22. Apply confining pressure and axial pressure: Start pump one 9, apply confining pressure and axial pressure to the core, set the surrounding rock pressure parameters according to the test requirements, and monitor the pressure in real time through the surrounding rock pressure monitor 8.

[0072] Step S3. Grouting injectability test for modification, including:

[0073] Step S31. Start the grouting system 3: Start the peristaltic pump 4 and switch to the piston container one 5 to drive the slurry to be injected into the core at a set pressure and flow rate; The peristaltic pump 4 ensures stable flow conditions by controlling the flow velocity and flow rate of the slurry to simulate seepage;

[0074] During this process, the peristaltic pump 4 continuously injects the slurry into the core to simulate the seepage process of the grouting liquid, while adjusting the flow rate and pressure to meet different test requirements;

[0075] In some embodiments, the slurry is injected into the core at a pressure of 0 - 16 MPa and a flow rate of 0.1 - 50 mL / min.

[0076] Step S32, oil - water separation and slurry quantitative analysis: When the test involves the distinction between the slurry and pore water, the oil - water separation system will be started to help separate the pore water in the original porous medium from the injected slurry; the slurry and the oil phase (replacing the pore water) in the core are separated by the oil - water separator 12, and the proportion of the slurry and the separation effect of oil and water can be quantitatively measured, so as to judge the effect of grouting;

[0077] In some embodiments, the sapphire window cooperates with the camera monitor 13 to record the volume proportion of the slurry, and the slurry proportion satisfies the following relationship:

[0078]

[0079] V 总 =V 活塞容器 +V 油浆中浆液量 +V 油浆中油液量 ;

[0080] Where:

[0081] V 浆 : Calculates the effective injection volume of the slurry during the experiment, that is, the initial slurry minus the un - penetrated oil, residual slurry, and part of the slurry in the pipeline;

[0082] V 总 : Calculates the total liquid volume of the entire experimental system, including the initial volume of the piston container and the measured slurry and oil volumes during the oil - water separation process;

[0083] V 活塞容器 : The total initial volume of the piston container;

[0084] V 油 : At the start of the experiment, the volume of oil in the piston container used to replace the pore water;

[0085] V 残余量 : After the experiment, the volume of residual slurry remaining in the piston container;

[0086] V 油浆中浆液量 : The slurry volume measured from the oil - water separation system;

[0087] V 油浆体积 : The total volume of oil and slurry measured from the oil - water separation system;

[0088] V 管路体积: The volume of liquid contained in the pipeline;

[0089] The ratio of the slurry volume to the oil slurry volume in the oil slurry is used to calculate the proportion of the slurry in the pipeline, avoiding overestimating the effective injection volume of the slurry.

[0090] Application of the experimental results of slurry quantitative analysis:

[0091] When the slurry proportion is high, it indicates that the injectability of the rock mass is good, and the slurry can penetrate into the pore medium more smoothly;

[0092] When the slurry proportion is low, it indicates that the injectability of the rock mass is poor, and there may be a low mixing ratio of the slurry and oil, or the slurry flow is blocked in the rock mass.

[0093] Step S33, Pressure dynamic regulation: The outlet pressure monitor 6 monitors the outflow pressure P3 of the slurry in real time, and the back pressure valve 15 adjusts the outflow pressure P3 according to the feedback signal to ensure the stable flow of the grouting liquid; The back pressure valve 15 is adjusted in real time to cope with different grouting pressures, ensuring that the pore water pressure and the slurry injection pressure in the core remain balanced throughout the experiment.

[0094] Step S4, In-situ test on mining-induced stress-seepage characteristics, including:

[0095] Step S41, Stress path switching: Stop the grouting system 3, switch the piston container one 5 to the piston container two 14, and turn on the water injection mode; Adjust the confining pressure and axial pressure through the pump one 9 to simulate the dynamic change of mining-induced stress, such as pressure relief or pressurization;

[0096] Step S42, Seepage parameter monitoring: Collect the surrounding rock pressure P2, pore water pressure P1 and seepage rate in real time, and quantitatively analyze the seepage flow rate in combination with the electronic balance;

[0097] Step S43, Data synchronous analysis: The data collected by the pressure sensor 17 and the visual metering system are transmitted to the data analysis software to generate a stress-seepage coupling curve.

[0098] Step S5, Test termination and data integration, including:

[0099] Step S51, Stop loading: Turn off the metering pump 4, pump one 9 and back pressure valve 15, and gradually remove the axial pressure, confining pressure and pore water pressure;

[0100] Step S52, Data export: Integrate the data of pressure, flow rate, slurry proportion and seepage path, and evaluate the injectability of the grouting material and the seepage characteristics under mining-induced stress

[0101] Step S53, Core recovery: Disassemble the core holder, take out the slurry-rock cemented body (the core after the test), and use it for subsequent mechanical property tests.

[0102] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0103] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A modified rock mining stress-seepage characteristic test device, characterized in that: include: A core holder (7) for fixing the core and applying axial pressure, confining pressure and pore water pressure; A grouting system (3) comprising a horizontal flow pump (4) connected to one end of a core holder (7) and a piston container (5); A confining pressure system (2), comprising a pump (9) connected to the peripheral side and the end of the core holder (7), wherein the pump (9) is used to apply annular pressure and axial pressure to the core holder (7); A back pressure system (1) comprises a pump 2 (18) connected to one end of a core holder (7), a back pressure valve (15) and a back pressure buffer container (16); An oil-water separation system comprises an oil-water separator (12) disposed between a back pressure system (1) and a core holder (7); The stress switching system comprises a second piston container (14) connected to one end of the core holder (7), wherein the second piston container (14) is connected to the horizontal flow pump (4); The data acquisition system comprises an inlet pressure monitor (11) and an outlet pressure monitor (6) arranged at both ends of a core holder (7), and a surrounding rock pressure monitor (8) arranged around the core holder (7).

2. The modified rock mining stress-seepage characteristic test device according to claim 1 is characterized in that: The axial pressure, confining pressure and pore water pressure of the core holder (7) are independently adjusted, and the maximum loading pressure is 30 MPa.

3. The modified rock mining stress-seepage characteristic test device according to claim 1, characterized in that: The pressure range of the horizontal flow pump (4) is 0-30 MPa, and the flow accuracy is ±0.1 mL / min.

4. The modified rock mining stress-seepage characteristic test device according to claim 1, characterized in that: The pressure regulation accuracy of the back pressure system (1) is 0.01 MPa.

5. The modified rock mining stress-seepage characteristic test device according to claim 1, characterized in that: The oil-water separator (12) is equipped with a sapphire window, a measuring range of 50 mL, and a pressure resistance of 30 MPa.

6. The modified rock mining stress-seepage characteristic test device according to claim 5, characterized in that: The oil-water separator (12) analyzes the slurry ratio through the cooperation of a video monitoring device (13) and a sapphire window.

7. The modified rock mining stress-seepage characteristic test device according to claim 1 is characterized in that: It also includes a visual metering system, which includes a sapphire window arranged on the oil-water separator (12) and a video monitoring device (13) facing the sapphire window.

8. The modified rock mining stress-seepage characteristic test device according to claim 1, characterized in that: The second piston container (14) and the first piston container (5) are respectively arranged at the two ends of the core holder (7) and are used to simulate the dynamic infiltration of pore water under mining stress.

9. A modified rock mining stress-seepage characteristic test method, according to the modified rock mining stress-seepage characteristic test device according to any one of claims 1-8, characterized in that: The following steps are involved: Step S1: Preparation before the test, including device assembly and core installation; Step S2: simulating the original rock stress environment, applying pore water pressure, confining pressure and axial pressure; Step S3: starting the grouting system (3), injecting slurry at a set pressure and flow rate, and quantitatively analyzing the slurry ratio through the oil-water separator (12); Step S4: Switch the stress system to simulate the dynamic change of mining stress, monitor the seepage parameters in real time and generate a stress-seepage coupling curve; Step S5: Terminate the test, integrate the data and evaluate the grouting injectability and seepage characteristics under mining stress.

10. The modified rock mining stress-seepage characteristic test method according to claim 9, characterized in that: In step S4, the stress-seepage characteristics of the rock modified by grouting under the condition of dynamic change of mining stress are simulated by switching the piston container 2 (14) and adjusting the confining pressure and the axial pressure.

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