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CN-121995013-A - Multi-field coupling simulation test system and method for water storage and heat collection of abandoned mine goaf

CN121995013ACN 121995013 ACN121995013 ACN 121995013ACN-121995013-A

Abstract

A multi-field coupling simulation test system for water storage and heat collection of a abandoned mine goaf comprises a bearing box body, a test sample filled in the bearing box body, a stratum pressure loading mechanism arranged above the test sample, a ground temperature simulation heating assembly paved at the bottom of the bearing box body, a recharging well, a pumping heat collection well, a recharging well, a pumping heat collection assembly, a pumping heat collection well, a plurality of liquid pressure sensors, a thin film distributed pressure sensor, a plurality of temperature sensors, a displacement sensor, a loading plate and an industrial camera. The invention can realize the comprehensive simulation of the evolution of the seepage field, the temperature field and the structural field in the water storage and heat collection process of the abandoned coal mine goaf.

Inventors

  • MENG FANFEI
  • LIU WANG
  • CHEN YONGHANG
  • LI JIAQI
  • ZHANG RUI

Assignees

  • 南华大学
  • 中国矿业大学

Dates

Publication Date
20260508
Application Date
20260325

Claims (10)

  1. 1. The multi-field coupling simulation test system for water storage and heat collection of the abandoned mine goaf comprises a bearing box body (32) and a test sample (1), and is characterized by further comprising a stratum pressure loading mechanism, a ground temperature simulation heating assembly (6), a seepage circulation mechanism, a multi-parameter monitoring unit and a sampling and post-processing unit; the bearing box body (32) is of a transparent structure, and a bearing cavity with an opening at the upper end is defined in the bearing box body; The test sample (1) is filled in the bearing cavity; the stratum pressure loading mechanism is arranged in the bearing cavity and is positioned above the test sample (1), and comprises a balancing weight (5), a loading plate (4) and a flexible pad (3) which are sequentially distributed from top to bottom, wherein a plurality of balancing weights (5) are uniformly distributed at the upper end of the loading plate (4); The ground temperature simulation heating assembly (6) is paved at the bottom of the bearing cavity; The seepage circulation mechanism comprises a recharging well (7), a pumping heat-collecting well (8), a recharging assembly and a pumping heat-collecting assembly, wherein the recharging well (7) and the pumping heat-collecting well (8) are distributed at left and right intervals and extend into the test sample (1) after penetrating through the stratum pressure loading mechanism; The multi-parameter monitoring unit comprises a liquid pressure sensor (14), a film distributed pressure sensor (16), a temperature sensor (15), a displacement sensor (21) and an industrial camera (17), wherein the liquid pressure sensors (14) are buried in different space positions in a test sample (1) at intervals, the film distributed pressure sensor (16) is laid at the bottom of the test sample (1), the temperature sensors (15) are buried in different space positions in the test sample (1) at intervals, the displacement sensor (21) is mounted at the upper end of a bearing box body (32) and connected with a loading plate (4), and the industrial camera (17) is arranged on one side outside the bearing box body (32).
  2. 2. The multi-field coupling simulation test system for water storage and heat collection of the abandoned mine goaf is characterized in that the multi-parameter monitoring unit further comprises a data processing terminal (18), and the data processing terminal (18) is respectively connected with a liquid pressure sensor (14), a film distributed pressure sensor (16), a temperature sensor (15), a displacement sensor (21), an industrial camera (17), a ground temperature simulation heating component (6), a recharging component and a water pumping and heat collection component.
  3. 3. The multi-field coupling simulation test system for water storage and heat collection of the abandoned mine goaf according to claim 1, wherein the bearing box body (32) comprises a supporting frame (20) and a transparent water tank (2), the transparent water tank (2) is installed in the supporting frame (20), a water outlet (19) is formed in the bottom of one side of the transparent water tank (2), and a plug is installed at the water outlet (19).
  4. 4. The multi-field coupling simulation test system for water storage and heat collection of the abandoned mine goaf is characterized in that the loading plate (4) is made of stainless steel plates, and the flexible pad (3) is made of silica gel.
  5. 5. The multi-field coupling simulation test system for water storage and heat collection of the abandoned mine goaf according to claim 1 is characterized in that the recharging assembly comprises a recharging water tank (9), a first motor (10) and a recharging pump (11); The transmission shaft of the recharging pump (11) is coaxially connected with the output shaft of the motor I (10), the liquid inlet of the recharging pump is connected with the recharging tank (9) through a liquid supplementing pipeline (28), and the liquid outlet of the recharging pump is connected with the inlet end of the recharging well (7) through a filling pipeline (29); The multi-parameter monitoring unit further comprises an electromagnetic flowmeter I (12) and a pressure transmitter I (13), and the electromagnetic flowmeter I (12) and the pressure transmitter I (13) are sequentially connected to the filling pipeline (29).
  6. 6. The multi-field coupling simulation test system for water storage and heat collection of the abandoned mine goaf according to claim 1 is characterized in that the water pumping and heat collection assembly comprises a water pumping and collection tank (23), a second motor (24) and a pumping and collection pump (25); The transmission shaft of the extraction pump (25) is coaxially connected with the output shaft of the motor II (24), the liquid inlet of the extraction pump is connected with the outlet end of the extraction heat extraction well (8) through the extraction pipeline (30), and the liquid outlet of the extraction pump is connected with the extraction water tank (23) through the liquid discharge pipeline (31); The multi-parameter monitoring unit further comprises a second electromagnetic flowmeter (26) and a second pressure transmitter (27), and the second electromagnetic flowmeter (26) and the second pressure transmitter (27) are sequentially connected to the extraction pipeline (30).
  7. 7. The multi-field coupling simulation test system for water storage and heat collection of the abandoned mine goaf is characterized in that the test sample (1) is a broken coal rock mass, and the transparent water tank (2) is made of acrylic materials.
  8. 8. A multi-field coupling simulation test method for water storage and heat collection in a goaf of a abandoned mine, which adopts the multi-field coupling simulation test system for water storage and heat collection in a goaf of a abandoned mine according to any one of claims 1 to 7, and is characterized by comprising the following steps: S1, determining test operation conditions and setting test parameters; s2, preparing a test sample (1); s3, assembling and testing a test system; S4, establishing a stress and temperature field, loading a plurality of balancing weights (5) in a display mode on a loading plate (4), collecting stress signals at the bottom of a test sample (1) in real time through a film distributed pressure sensor (16), stopping until the stress value in the test sample (1) reaches a target loading stress value range, and simultaneously starting a ground temperature simulation heating assembly (6) to heat until the internal temperature of the test sample (1) reaches a preset ground temperature boundary value; In the simulation process, the filling flow of seepage liquid is collected in real time through a first electromagnetic flowmeter (12), the filling pressure signal of the seepage liquid is collected in real time through a first pressure transmitter (13), the extraction flow of the seepage liquid is collected in real time through a second electromagnetic flowmeter (26), the extraction pressure signal of the seepage liquid is collected in real time through a second pressure transmitter (27), the hydraulic pressure signals at different space positions in the test sample (1) are collected in real time through a plurality of liquid pressure sensors (14), the stress signals at the bottom of the test sample (1) are collected in real time through a thin film distributed pressure sensor (16), the temperature signals at different space positions in the test sample (1) are collected in real time through a temperature sensor (15), the displacement signals of a loading plate (4) are collected in real time through a displacement sensor (21), and the image data of the seepage flow process and the structural change are collected in real time through an industrial camera (17); s6, stopping and unloading the test, controlling the recharging assembly and the water pumping and heating assembly to stop after reaching a preset stopping condition, controlling the ground temperature simulation heating assembly (6) to stop the industry, removing a plug in the water outlet (19) to perform water draining operation, and then unloading the balancing weights (5) in a grading way; S7, forming an in-situ consolidated body, namely injecting the heated and melted infiltration consolidation material into a bearing cavity in a partial or integral pouring mode, enabling the infiltration consolidation material to enter pores in a sample (1) by utilizing capillary action and gravity action and wrap particles to form the consolidated body with an in-situ structure; S8, grid sampling and three-dimensional quantitative characterization, S81, namely performing space positioning sampling on a consolidated body according to a pre-designed grid coordinate, acquiring an original structure sample at each sampling position according to the principle of in-situ and low disturbance in the sampling process, and S82, scanning the original structure sample by using a CT scanning technology, and acquiring pore structure parameters and particle space distribution characteristics of the sample by a three-dimensional reconstruction analysis method to realize quantitative characterization on a blocking area and structure evolution.
  9. 9. The multi-field coupling simulation test method for water storage and heat collection of the abandoned mine goaf according to claim 8, wherein in the step S2, the preparation process of the test sample (1) is as follows: Firstly, collecting an on-site coal and rock sample, crushing the coal and rock sample by using a jaw crusher to prepare crushed coal and rock particles, screening and grading the crushed coal and rock particles to obtain crushed coal and rock particles with different particle sizes, and then, carrying out differential dyeing treatment on the surfaces of the crushed coal and rock particles with different particle sizes by adopting water-resistant dyes with different colors, and then, naturally airing and drying to form a test sample (1) with traceable marks.
  10. 10. The multi-field coupling simulation test method for water storage and heat collection of the abandoned mine goaf according to claim 9, wherein in S3, the assembly and test process of the test system is as follows: S31, installing a ground temperature simulation heating assembly (6) at the bottom of a bearing cavity in a bearing box body (32), and paving a film distributed pressure sensor (16) above the ground temperature simulation heating assembly (6); s32, loading a test sample (1) into a bearing cavity in a layered filling mode, and respectively burying a plurality of liquid pressure sensors (14) and a plurality of temperature sensors (15) at preset positions; S33, sequentially paving a flexible pad (3) and a loading plate (4) above the test sample (1), and simultaneously, installing a displacement sensor (21) at the upper end of a bearing box body (32) and connecting the displacement sensor with the loading plate (4); S34, enabling the lower ends of the recharging well (7) and the pumping and heating well (8) to penetrate through the flexible pad (3) and the loading plate (4) and extend into the test sample (1), enabling the recharging assembly to be connected with the recharging well (7), and enabling the pumping and heating assembly to be connected with the pumping and heating well (8); and S35, starting the recharging assembly and the water pumping and heat collecting assembly, and circularly operating for 20-30 min under the set flow condition, so that no leakage of each part of the system is ensured, and the operation condition is stable.

Description

Multi-field coupling simulation test system and method for water storage and heat collection of abandoned mine goaf Technical Field The invention belongs to the technical field of water storage and heat collection of goafs of abandoned coal mines, and particularly relates to a multi-field coupling simulation test system and method for water storage and heat collection of goafs of abandoned coal mines. Background Along with the continuous increment of the coal resource exploitation depth in China, the coal exploitation is gradually transferred to the deep part. By 2015, there have been about 47 coal mines over 1000m in depth nationwide, and the production depth is increasing at a rate of about 10-25 m per year. Under deep mining conditions, the temperature of the surrounding rock of the mine rises significantly, and the average ground temperature gradient is about 1-3 ℃ per 100m. When the mine is buried to a kilometer level, the surrounding rock temperature is typically 35-45 ℃. Meanwhile, under the influence of coal resource exhaustion and industrial structure adjustment, the number of abandoned coal mines in China is estimated to reach about 15000 in 2030. These abandoned mines contain a large amount of unutilized geothermal resources, mine water resources, and underground space resources. The existing statistics show that about one third of coal mines which are withdrawn from operation in China are water-rich mines, the volume of the left underground space is about 80 Mm 3, and good water storage and heat collection conditions are provided for waste coal mines. All caving methods are generally adopted for managing the top plate of the underground coal mine, and after stoping of the coal face, the overlying strata is caving to form a large-scale goaf. The goaf is filled with broken coal blocks and rock blocks, and has the characteristics of high porosity (generally 30% -45%), large specific surface area, good heat exchange condition and the like. Therefore, the waste mine water storage and heat collection technology taking the goaf as a heat storage space and mine water as a heat transfer medium is regarded as a geothermal resource utilization mode with great application prospect, and has positive significance for pushing a double-carbon target. However, in actual operation, broken rock mass in goaf is subjected to combined action of mine water seepage erosion, overburden pressure and ground temperature for a long time, and the internal structure of the broken rock mass presents obvious spatial heterogeneity. Under the multi-field coupling effect of seepage-temperature-formation pressure, the inter-rock mass contact relation and the bearing framework structure are continuously adjusted. In addition, the crushed rock mass is easy to be crushed secondarily in the long-term service process, and a large amount of fine particles are generated. These particles fall off and migrate under the action of mine water flow and accumulate at the pore or fracture throat, which results in narrowing of the seepage channel and even blockage conditions, and further results in attenuation of the infiltration capacity and recharging capacity of the goaf. Moreover, the rock mass breaking and particle migration processes not only can cause the deterioration of seepage performance, but also can weaken the whole bearing framework structure of the goaf broken rock mass. In extreme cases, secondary sedimentation of the overburden may even be induced, adversely affecting the safety of the wellbore structure. Therefore, in order to realize efficient, safe and controllable operation of the water storage and heat collection engineering of the abandoned coal mine goaf, a system is needed to study the evolution rule of the space structure of broken rock mass of the goaf under the multi-field coupling effect of seepage, temperature and formation pressure, and reveal the particle migration and blockage formation mechanism so as to effectively evaluate the blockage risk and predict the potential blockage area, thereby providing scientific basis for design optimization and operation regulation and control of the water storage and heat collection engineering. Disclosure of Invention Aiming at the problems in the prior art, the invention provides the water storage and heat collection multi-field coupling simulation test system and the method for the abandoned mine goaf, which have the advantages of simple structure, low manufacturing cost and convenient operation process, can effectively simulate the stratum pressure effect of goaf overlying strata on test samples, can realize comprehensive on-line observation of the structural change of the test samples under visual conditions, and can provide a good test basis for follow-up structural sampling and CT three-dimensional scanning reconstruction analysis. The method has the advantages of simple implementation process and low implementation cost, can realize comprehensive simulation of the evoluti