A method for testing a compressed air reservoir in a coal roadway

Abstract

The present application relates to a kind of coal lane compressed air reservoir test methods, comprising the following steps: place the lining structure model of inside face being equipped with detection element on stratum model, and the two ends of lining structure model are sealed using sealing assembly;In the periphery of lining structure model, surrounding rock damage area is filled, and surrounding rock damage area includes multiple surrounding rock blocks filled by surrounding rock similar material, the gap between adjacent surrounding rock blocks is filled with fissure layer, and detection element is embedded during surrounding rock block filling;Overburden zone is filled outside surrounding rock damage area;Permeable water is introduced into the top of overburden zone, and the gas reservoir in the inside of lining structure model is aerated and discharged, and the parameters obtained by detection element detection are recorded, the method of the present application can reveal the mechanism problem encountered in the process of coal lane reconstruction into compressed air reservoir by test means.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, specifically to a test method for a compressed air storage tank in a coal roadway. Background Technology

[0002] Underground gas storage facilities primarily utilize depleted oil and gas reservoirs and salt caverns for construction. While offering excellent sealing and low construction costs, their reliance on specific geological structures makes large-scale deployment in first-tier cities difficult. Converting existing abandoned mine shafts into compressed air storage facilities would further enhance the deep application of energy storage technology, promote a cleaner energy structure transformation, and create grid-friendly power sources with self-shaving and valley-filling capabilities and stable output, resulting in significant economic benefits.

[0003] Analogous to the requirements for salt cavern construction, the conversion of abandoned mine tunnels requires consideration of the airtightness, stability, and durability of the gas storage facility. Air compression, storage, and release involve thermodynamic changes that affect the temperature, stress, and deformation of structures such as the sealing layer, lining, and surrounding rock. Unlike newly built hard rock chambers, the conversion of abandoned mine tunnels into storage facilities has unique characteristics under typical gas filling and releasing operation modes. These characteristics include: significant damage to the surrounding rock in abandoned coal mine tunnels, necessitating solutions to the stability issues of using abandoned tunnels for compressed air energy storage; the impact of water seepage on storage facility operation needs to be considered; the problem of localized damage to the sealing layer caused by defects such as lining cracks remains unresolved; and the temperature of the released compressed air in the storage facility is below zero degrees Celsius, placing it in a sub-zero temperature state. Large-scale experimental research is needed to study the key scientific issues encountered in the construction and operation of coal mine tunnel energy storage facilities, but currently, corresponding experimental methods are lacking, and the mechanistic problems encountered in the conversion of abandoned coal mine tunnels into compressed air storage facilities cannot be revealed. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a test method for compressed air storage in coal roadways, which can reveal the mechanistic problems encountered in the process of converting coal roadways into compressed air storage through testing.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] An embodiment of the present invention provides a test method for a compressed air storage tank in a coal roadway, characterized by comprising the following steps:

[0007] A lining structure model with detection elements on its inner surface is placed on the stratum model, and both ends of the lining structure model are sealed using a sealing component.

[0008] A surrounding rock damage zone is filled around the outer periphery of the lining structure model. The surrounding rock damage zone includes multiple surrounding rock blocks filled with similar surrounding rock materials. The gaps between adjacent surrounding rock blocks are filled with a fracture layer. Detection elements are embedded during the filling process of the surrounding rock blocks.

[0009] Fill the overlying surrounding rock zone outside the damaged surrounding rock zone;

[0010] Infiltrate water into the top of the overlying rock area, and inflate and deflate the gas storage tank inside the lining structure model, recording the parameters obtained from the detection elements.

[0011] Optionally, a sealing layer is provided on the inner surface of the lining structure model, and distributed optical fibers and stress gauges are provided on the inner surface of the sealing layer as detection elements for the inner surface of the lining structure model.

[0012] Optionally, the sealing layer includes a first sealing layer located on the inner surface of the lining structure model and a second sealing layer located on the surface of the first sealing layer. The first sealing layer is made of phenolic foam material, B1 grade polyurethane sprayed insulation material, or foamed cement, and the second sealing layer is made of steel plate, butyl rubber, EPDM rubber, natural rubber, or fiberglass.

[0013] Optionally, for a horizontal or horizontally oriented fracture material layer, the surrounding rock blocks below it are first filled in, and then a fracture template is placed on top of the filled surrounding rock blocks and compacted to form a surface along the fracture shape. Then the fracture template is removed, and a fracture-like material is laid to form a fracture layer. Then the surrounding rock blocks above the fracture layer are filled in. For a vertical fracture layer, a fracture template is first placed in, and then the surrounding rock blocks on both sides of the fracture template are filled in. After the fracture template is removed, a fracture-like material is blown in to form a fracture layer.

[0014] Optionally, when filling the surrounding rock damage zone, all surrounding rock blocks are filled, and crack templates are set between adjacent surrounding rock blocks. Then, along the longitudinal direction of the lining structure model, the crack templates are pulled out from one side while crack-like materials are blown in from the other side.

[0015] Optionally, during the filling of the surrounding rock damage zone, all surrounding rock blocks are filled, and crack templates are set between adjacent surrounding rock blocks. The crack templates are made of water-soluble support material. Holes are drilled into the crack templates and water is injected, causing the crack templates to gradually dissolve. At the same time, crack-like materials are blown in.

[0016] Optionally, the sealing component is a concrete air plug cast at the end of the lining structure model, wherein one end of the concrete air plug is provided with an air inlet and an air outlet.

[0017] Furthermore, an expansion membrane bag is installed between the concrete air plug and the inner side of the end of the lining structure model. After the concrete air plug is poured, cement-water glass quick-setting grout is injected into the expansion membrane bag. After the expansion membrane bag expands, it seals the concrete air plug and the inner side of the lining structure model.

[0018] Optionally, the lining structure model is filled and vented using a filling and venting mechanism. The filling and venting mechanism includes a compressed air supply element connected to one end of an air inlet pipe. The other end of the air inlet pipe extends into the interior space of the lining structure model through an air inlet hole. An air outlet pipe is fixed at the air outlet, which connects the interior space of the lining structure model with the external space. Both the air inlet pipe and the air outlet pipe are equipped with valves.

[0019] Optionally, the detection elements inside the surrounding rock block are multiple piezometers and stress gauges.

[0020] Optionally, a water tank is placed on top of the overlying rock area, the tank is filled with water, and the bottom wall of the tank is provided with a water inlet to allow water to flow into the overlying rock area.

[0021] Furthermore, a heating element is installed inside the water tank.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. The experimental method of this invention establishes a surrounding rock damage zone around the outer periphery of the lining structure model. The surrounding rock damage zone includes multiple surrounding rock blocks, with a layer of fractured material between adjacent surrounding rock blocks, simulating the non-homogeneous damage effect of the surrounding rock. By introducing permeable water into the top of the overlying surrounding rock layer, it simulates the structural performance degradation effect caused by seepage, temperature and internal pressure cyclic loading and unloading, lining cracking and back-wall voids, or local damage to the sealing layer caused by segmented lining displacement deformation. It comprehensively considers various unfavorable conditions for the construction of coal roadways into compressed air storage tanks, and can more realistically simulate the actual working conditions of coal roadways. It realizes the revelation of the mechanistic problems encountered in the process of converting coal roadways into compressed air storage tanks through experimental means, and has significant theoretical guiding significance.

[0024] 2. The experimental method of this invention, by simulating various unfavorable conditions in coal roadways and including lining structure models and sealing components, can be used to study the influence of structural parameters (such as various lining forms and thicknesses, sealing layer materials and forms, formation temperature, etc.) and operational parameters (such as injection temperature, inflation / deflation rates, minimum operating pressure, etc.) on the stability, airtightness, and durability of compressed air storage facilities during operation. This provides supplementary data and reliability verification for numerical simulation work. By controlling operational parameters, it helps to quantitatively analyze the thermodynamic changes (temperature and pressure changes) of compressed air within the storage facility, providing scientific guidance for the construction and operation of gas storage facilities in abandoned coal roadways. Through long-term inflation / deflation operation, the leakage rate of the gas storage facility is measured, which helps to improve the sealing methods at the roadway sealing ends and also verifies the durability of existing lining methods. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Figure 1 This is a flowchart of the method in Embodiment 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the lining structure model, the surrounding rock damage zone, and the overlying surrounding rock zone prepared by the method in Embodiment 1 of the present invention;

[0028] Figure 3 This is the present invention. Figure 2 Enlarged view of section A in the image;

[0029] Figure 4 This is the present invention. Figure 2 Enlarged view of section B in the image;

[0030] Figure 5 This is a schematic diagram of the inflation / deflation mechanism installation in Embodiment 1 of this product;

[0031] Figure 6 This is the present invention. Figure 5 Enlarged view of a section at point C;

[0032] Figure 7 This is a schematic diagram of the distribution of distributed optical fibers within the lining structure model according to Embodiment 1 of the present invention;

[0033] Among them, 1. First surrounding rock block, 2. Second surrounding rock block, 3. Third surrounding rock block, 4. Fourth surrounding rock block, 5. Fifth surrounding rock block, 6. Sixth surrounding rock block, 7. Lining structure model, 8. First sealing layer, 9. Second sealing layer, 10. First fracture layer, 11. Second fracture layer, 12. Third fracture layer, 13. Fourth fracture layer, 14. Fifth fracture layer, 15. Inlet pipe, 16. Outlet pipe, 17. Concrete air plug with pipe hole, 18. Inlet valve 19. Concrete air plug, 20. Air compressor, 21. Thermometer, 22. Air flow meter, 23. Thermometer, 24. Air flow meter, 25. Outlet valve, 26. Pressure gauge, 27. Distributed optical fiber, 28. Piezometer, 29. Stress gauge, 30. Bolt, 31. Expansion membrane bag, 32. Gap, 33. Overlying rock area, 34. Water tank, 35. Thermistor temperature-sensing heating rod, 36. Formation model, 37. Gas storage tank. Detailed Implementation

[0034] Example 1:

[0035] This embodiment provides a test method for compressed air storage tanks in coal roadways, such as... Figures 1-6 As shown, it includes the following steps:

[0036] Step 1: Prepare surrounding rock similar materials and fracture filling similar materials. The surrounding rock similar materials are used for the stratigraphic model, the damaged surrounding rock zone, and the overlying surrounding rock zone. The stratigraphic model is the lowest model, used to support the lining structure model, the damaged surrounding rock zone, and the overlying surrounding rock zone. The damaged surrounding rock zone is the surrounding rock similar material set within a defined area around the lining structure model, and the overlying surrounding rock zone is the surrounding rock similar material set outside the damaged surrounding rock zone. The specific method is as follows:

[0037] Step a: Determine the similarity ratio of the model test based on the principle of fluid-structure interaction similarity.

[0038] Step b: Conduct strength and permeability tests on the original rock, which includes two steps: First, core sampling is carried out on-site in the target stratum, and the core samples are prepared into standard test specimens. Second, according to the test procedures, the compressive strength and permeability of the original rock are tested using a uniaxial testing machine and a permeameter, and the test results are obtained.

[0039] Step c: Develop fluid-structure interaction similar materials and fracture-filling similar materials, comprising two steps: First, select raw materials based on the performance requirements of the developed materials. Second, design the similar material mix proportions, and prepare three strength test specimens and three permeability test specimens for each mix proportion. Test the uniaxial compressive strength and permeability of the basic mechanical parameters of the similar materials to determine the control range of the similar material's strength. Third, compare the strength and permeability of the original rock and the similar materials based on the physical and mechanical parameters of the original rock and the similarity ratio to obtain the corresponding similar mix proportions. The design principle of the fracture-filling material is that under the self-weight stress of the overlying strata, the fracture-filling layer undergoes blocky fracture, forming natural fractures. Its compressive strength is relatively low, and the self-weight stress of the strata can be calculated. Based on this principle, the mix proportion of the fracture-filling material is selected.

[0040] Based on the material ratios determined above, prepare corresponding surrounding rock similar materials and fracture filling similar materials.

[0041] The above steps can be performed using existing methods, and the details of the methods will not be described in detail here.

[0042] In this embodiment, the material parameters of the strata, the damaged surrounding rock zone, and the overlying surrounding rock zone are compared with the material parameters of the rock sample in the following table:

[0043] Table 1: Parameter Table of Similar Materials

[0044]

[0045] Step 2: Construct the lining structure model 7. The lining structure model adopts conventional reinforced concrete lining, grouting prestressed lining, ring anchor prestressed lining, or segmented lining. The cross-sectional shape of the tunnel can be rectangular, trapezoidal, straight-wall semi-circular arch, three-center arch, closed arch, elliptical, or circular.

[0046] In this embodiment, the lining structure model 7 is a segmented lining structure model, the tunnel cross-section shape is a straight wall semi-circular arch, and the thickness of the lining structure model is 10cm-50cm.

[0047] Includes cube blocks for the straight walls and semi-circular blocks for the arches.

[0048] The entire lining structure model is formed by fixing cube blocks to both ends of the semi-circular block.

[0049] In this embodiment, the cube block and the semi-circular block are connected by bolts 30, and a sealing layer is provided inside the lining.

[0050] The sealing layer consists of two layers, including a first sealing layer 8 set on the inner side of the lining structure model and a second sealing layer 9 set on the inner side of the first sealing layer.

[0051] The first sealing layer (8 materials) should prioritize thermal insulation, and can be made of phenolic foam, B1 grade polyurethane spray insulation, foamed cement, etc.

[0052] In this embodiment, the first sealing layer 8 is a 2cm thick foamed cement layer. The foamed cement is sprayed onto the inner surface of the lining structure model.

[0053] The material of the second sealing layer 9 is designed with sealing performance in mind. It can be made of steel plate, butyl rubber, EPDM rubber, natural rubber and fiberglass, etc., with a thickness ranging from 0.5cm to 2cm.

[0054] In this embodiment, the second sealing layer 9 is made of 1cm thick butyl rubber, which is fixed to the inner surface of the foamed cement layer by hot melting.

[0055] Distributed optical fibers 27 and stress gauges 29 are installed on the inner side of the second sealing layer corresponding to the semi-circular block to detect the temperature and strain changes of the structure during the air inflation and deflation tests inside the lining structure model.

[0056] like Figure 7 As shown, the distributed optical fiber 27 is divided into multiple segments, each segment is laid along the axial direction of the lining structure model, and multiple segments are laid along the circumference of the semi-circular block.

[0057] Step 3: Lay the stratum model 36 inside the bottom box wall of the model test phase. The stratum model 36 is laid using the surrounding rock similar material prepared in Step 1, which corresponds to the stratum model. The stratum is laid in layers. The same pressure as that used to prepare the similar material specimen is applied to the filled stratum for layered compaction.

[0058] Step 4: When the compaction height of the stratum model 36 reaches 10cm, place the lining structure model 7 made in Step 2 on the laid stratum model, and place sealing components at both ends of the lining structure model 7 for sealing. The sealing components are concrete air plugs 19 that match the cross-sectional shape of the lining structure model. The end of the concrete air plug 19 near the lining structure model has a conical annular protrusion. The outer edge dimension of the annular protrusion is larger than the outer edge dimension of the lining structure model. The inner side of the concrete air plug 19 near the lining structure model 7 is provided with a first sealing layer and a second sealing layer in sequence. The setting method of the first sealing layer and the second sealing layer is the same as the setting method of the first sealing layer and the second sealing layer on the inner side of the lining structure model.

[0059] An expansion membrane bag 31 is provided on the outer side of the concrete air plug. The expansion membrane bag 31 can be injected with cement-water glass quick-setting grout, so that after the expansion membrane bag expands, it can fill the gap 32 in the contact part between the concrete air plug and the surrounding rock damage area, and compact the similar material of the stratum model and the surrounding rock damage area, thereby improving the air tightness of the structure.

[0060] One side of the concrete air plug is equipped with an air inlet and an air outlet, forming a concrete air plug 17 with a pipe hole, which is used to inflate and deflate the internal space of the lining structure model 7.

[0061] In this embodiment, a double-layer insulation measure based on foamed cement is proposed to reduce heat exchange between the high-temperature, high-pressure air and the surrounding rock lining during operation. The detailed treatment of the concrete air plug, in particular, can be widely applied to practical engineering applications. While ensuring airtightness, it significantly reduces energy loss, contributing to an increase in the total power generation of the compressed air energy storage power station. The introduction of spray-type insulation materials also lays the foundation for intelligent and unmanned construction of sealing layers in coal mine roadway storage facilities in the future.

[0062] Step 5: Fill the surrounding rock damage zone around the lining structure model.

[0063] In this embodiment, the distance between the outer edge of the surrounding rock damage zone and the outer edge of the lining structure model is 0.8m-1.2m, preferably 1m, and the surrounding rock damage zone is filled within a 1m radius around the lining structure model.

[0064] Specifically, the surrounding rock damage zone includes the first surrounding rock block 1, the second surrounding rock block 2, the third surrounding rock block 3, the fourth surrounding rock block 4, the fifth surrounding rock block 5, and the sixth surrounding rock block 6.

[0065] A first fracture layer 10 is provided between the first surrounding rock block 1 and the second surrounding rock block 2. The first fracture layer 10 is set approximately horizontally. A second fracture layer 11 is provided between the second surrounding rock block 2 and the third surrounding rock block 3. The second fracture layer 11 is set at a certain acute angle to the horizontal direction. A third fracture layer 12 is provided between the third surrounding rock block 3 and the fourth surrounding rock block 4. The third fracture layer 12 is set approximately vertically. A fourth fracture layer 13 is provided between the fourth surrounding rock block 4 and the fifth surrounding rock block 5. The fourth fracture layer 13 is set at a set acute angle to the horizontal direction. A fifth fracture layer 14 is provided between the fifth surrounding rock block 5 and the sixth surrounding rock block 6. The fifth fracture layer 14 is set approximately horizontally.

[0066] The construction steps for the damaged rock zone in this embodiment are as follows:

[0067] The first surrounding rock block 1 and the sixth surrounding rock block 6 are filled with similar surrounding rock materials in layers. When the compaction height reaches the set value, the crack template is placed and the crack template is compacted so that the shape of the upper surface of the first surrounding rock block 1 and the sixth surrounding rock block 6 matches the shape of the crack.

[0068] The surrounding rock blocks were compacted in layers using the same pressure applied to prepare similar material specimens.

[0069] Remove the fracture template, and then lay fracture-like material along the upper surface of the first surrounding rock block 1 and the sixth surrounding rock block 6 to form the first fracture layer 10 and the fifth fracture layer 14.

[0070] The second surrounding rock block 2 and the fifth surrounding rock block 5 are filled in layers on the upper surfaces of the first fracture layer 10 and the fifth fracture layer 14, respectively. After filling to the set height, the upper surfaces of the second surrounding rock block and the fifth surrounding rock block 5 are squeezed into fracture shapes using the corresponding fracture template in the same way. Then the fracture template is removed, and fracture-like materials are laid on the upper surfaces of the second surrounding rock block 2 and the fifth surrounding rock block 5 to form the second fracture layer 11 and the fourth fracture layer 13.

[0071] A fissure template is placed in the middle of the arch of the lining structure model for positioning. Then, the third surrounding rock block 3 and the fourth surrounding rock block 4 on both sides are filled in layers. After the filling is completed, the two side boxes of the model box are disassembled in the direction perpendicular to the axis of the lining structure model, that is, in the longitudinal direction of the lining structure model. The fissure template is removed from one side along the axis of the lining structure model by connecting a traction machine with a steel cable. At the same time, a fissure-like material is blown into the gap between the third surrounding rock block 3 and the fourth surrounding rock block 4 by a sandblasting machine on the other side to form the third fissure layer 12.

[0072] After the surrounding rock damage zone is filled, cement-water glass quick-setting grout is injected into the expansion membrane bag 31. After the expansion membrane bag 31 expands, it compacts the strata and the surrounding rock-like material in the surrounding rock damage zone, improving the airtightness of the structure and reducing cracks.

[0073] During the layered filling process of the surrounding rock blocks, multiple detection elements are embedded, including piezometers and stress gauges. Piezometers 28 are embedded in the first, second, and third surrounding rock blocks, while stress gauges 29 are embedded in the remaining surrounding rock blocks. These are used to monitor changes in internal pressure and stress during the air inflation / deflation test.

[0074] The crack template is obtained by 3D printing, and the crack-similar material can be sand with a set moisture content.

[0075] Step 6: Reinstall the side walls of the model box, then fill the remaining area of ​​the model box with a material similar to the surrounding rock to form an overlying rock zone located outside the damaged surrounding rock zone. The overall dimensions of the model are 3m long, 3m wide, and 2m high.

[0076] Step 7: Install the inflation / deflation mechanism, which includes an air inlet pipe 15, an air outlet pipe 16, and a compressed air supply element. The compressed air supply element is an air compressor 20. The air inlet pipe 15 is inserted into the air inlet of the concrete air plug 19 on one side. One end of the air inlet pipe 15 is inserted into the air storage tank 37 formed inside the lining structure model 7, and the other end is connected to the air compressor 20 through the air inlet valve 18. The air outlet pipe 16 is installed at the air outlet, which connects the internal space and the external space of the lining structure model. An air outlet valve 25 is installed on the air outlet pipe.

[0077] The air inlet pipe 15 is also equipped with a pressure gauge 26, an air flow meter 22, and a temperature gauge 21. The pressure gauge 26 is used to detect the air pressure inside the lining structure model, the air flow meter 22 is used to detect the air flow during inflation, and the temperature gauge 21 is used to detect the inflation temperature.

[0078] An air flow meter 24 and a thermometer 23 are installed on the air outlet pipe 16, which are used to detect the air flow rate and air temperature, respectively.

[0079] In this embodiment, both the inlet valve and the outlet valve are ball valves.

[0080] The air compressor 20 pressurizes the air storage tank 37 formed inside the lining structure model 7. When the pressure gauge 16 on the air inlet pipe 15 shows 15MPa, the pressurization is terminated and the air inlet valve 18 on the air inlet pipe is immediately closed. The air flow meter 22 on the air inlet pipe 15 is used to monitor the air injection rate and realize the simulation of different air injection rate conditions.

[0081] Opening the vent valve 25 on the vent pipe 16 allows for venting. Combined with the initial flow rate display on the air flow meter 24 on the vent pipe, it accurately simulates different venting rates.

[0082] Step 8: Place a water tank 34 with heating elements installed inside on the top surface of the overlying rock area 33. The inlet of the water tank 34 is connected to the outlet of a constant pressure pneumatic diaphragm pump through a pipeline. The inlet of the constant pressure pneumatic diaphragm pump is connected to a water source through a pipeline. The constant pressure start diaphragm pump is connected to an air compressor to drive it to work and provide a pressurized aquifer.

[0083] In this embodiment, the heating element is a thermistor-type heating rod 35, which can heat the pressurized aquifer.

[0084] The bottom wall of the water tank 34 is provided with multiple water inlets so that the water tank can deliver infiltration water to the overlying surrounding rock area 33.

[0085] The heterogeneous damage is considered in two parts: first, the micro-cracks inside the surrounding rock caused by excavation, resulting in heterogeneous contact between the lining and the surrounding rock; second, the simulation of the infiltration-weakening-damage process of the strata under the long-term infiltration of groundwater. By setting steps 5 and 8, these two parts can be realistically simulated, ensuring the accuracy of the test results.

[0086] The above method is applicable to simulating the construction of heterogeneous damage zones in single-type and composite-type strata, with the simulated strata being uniformly isolated by muscovite powder.

[0087] Step 9: Begin the test by starting the air compressor of the inflation / deflation mechanism and the air compressor connected to the constant pressure pneumatic diaphragm pump. Establish a typical operating mode test procedure as follows:

[0088] During the gas storage phase, the initial gas pressure inside the gas storage tank formed by the interior space of the lining structure model is 100 kPa, and the gas injection temperature is 20℃. The maximum gas pressure inside the gas storage tank is controlled at 15 MPa. The inflation rate is monitored by an air flow meter on the inlet pipe and controlled by the air compressor 20 and valves on the inlet pipe. The inflation temperature is monitored by a temperature gauge on the inlet pipe. The final inflation pressure is monitored by a pressure gauge 26 on the inlet pipe.

[0089] During the gas release phase, the valve on the gas outlet pipe is opened and adjusted to control the standard gas release rate. The gas release rate is monitored by the air flow meter 24 on the gas outlet pipe, and the gas release temperature is monitored by the thermometer 23 on the gas outlet pipe.

[0090] During the gas storage and release stages, the distributed optical fiber 27 on the inner surface of the lining structure model can measure the temperature and strain changes of the lining structure and sealing layer during the air filling and releasing test, and the stress gauge 29 can measure the stress changes of the lining structure model and sealing layer structure during the air filling and releasing test.

[0091] Piezometers and stress gauges in the damaged area of ​​the surrounding rock were used to monitor changes in internal seepage pressure and stress during the air inflation / deflation test. The parameters measured by these detection elements were recorded.

[0092] The method in this embodiment simulates the non-homogeneous damage effect of the surrounding rock, the structural performance degradation effect caused by seepage, the temperature and internal pressure cyclic loading and unloading, lining cracking and back-wall voids, and the local damage to the sealing layer caused by segmented lining displacement deformation. It comprehensively considers various unfavorable conditions for the construction of coal roadways into compressed air reservoirs, and can more realistically simulate the actual working conditions of coal roadways. It reveals the mechanistic problems encountered in the process of converting coal roadways into compressed air reservoirs through experimental means, which has significant theoretical guiding significance. Moreover, by simulating various unfavorable conditions of coal roadways, and with lining structure models and sealing components, it can be used to study the influence of structural parameters (such as various lining forms and thicknesses, sealing layer materials and forms, formation temperature, etc.) and operating parameters (such as gas injection temperature, gas filling and discharging rate, minimum operating pressure, etc.) on the stability, airtightness and durability of compressed air reservoirs during operation, providing supplements and reliability verification for numerical simulation work. By controlling operational parameters, it is possible to quantitatively analyze the thermodynamic changes (temperature and pressure changes) of compressed air within the storage facility, providing scientific guidance for the construction and operation of gas storage facilities in abandoned coal roadways. Through long-term filling and discharging operations, the leakage rate of the gas storage facility can be measured, which helps to improve the sealing methods at the roadway sealing ends and also verifies the durability of existing lining methods.

[0093] Example 2

[0094] This embodiment provides a test method for compressed air storage in coal roadways. The only difference from Embodiment 1 is that when filling the damaged area of ​​the surrounding rock, all surrounding rock blocks and corresponding fracture templates are constructed. The construction sequence is as follows: first surrounding rock block, fracture template corresponding to the first fracture layer, sixth surrounding rock block, fracture template corresponding to the fifth fracture, second surrounding rock block, fracture template corresponding to the second fracture layer, fifth surrounding rock block, fracture template corresponding to the fourth fracture, fracture template corresponding to the third fracture, third surrounding rock block, and fourth surrounding rock block.

[0095] Then, remove the two side walls of the model box that are perpendicular to the axis of the lining structure model. In the order of first crack - fifth crack - second crack - fourth crack - third crack, the crack template is pulled out to one side along the axis of the lining structure model by a traction machine connected by a steel cable. At the same time, a crack-like material is sprayed into the crack from the other side by a sandblasting machine until the crack template is completely pulled out. Then, the side walls of the model box are reinstalled.

[0096] The crack template was obtained using 3D printing.

[0097] The other methods and steps are the same as in Example 1, and will not be repeated here.

[0098] Example 3

[0099] This embodiment provides a test method for compressed air storage in coal roadways. The difference from Embodiment 2 is that the fracture template is made of existing water-soluble support material. Specifically, it is made of water-soluble 3D printing consumable PVA. The fracture template is made into a three-dimensional curved surface shape, and the fracture thickness, fracture width, and fracture extensibility are all non-linear changes.

[0100] Remove the side box wall thickness perpendicular to the axis of the lining structure model, drill a hole on one side of the crack template and inject water to gradually melt the crack template, and spray crack-like material into the crack from the same side using a sandblasting machine.

[0101] The other methods and steps are the same as in Example 2, and will not be described in detail here.

[0102] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A test method for compressed air storage tanks in coal roadways, characterized in that, Includes the following steps: A lining structure model with detection elements on its inner surface is placed on the stratum model, and both ends of the lining structure model are sealed using a sealing component. A surrounding rock damage zone is filled around the outer periphery of the lining structure model. The surrounding rock damage zone includes multiple surrounding rock blocks filled with similar surrounding rock materials. The gaps between adjacent surrounding rock blocks are filled with a fracture layer. Detection elements are embedded during the filling process of the surrounding rock blocks. Fill the overlying surrounding rock zone outside the damaged surrounding rock zone; Infiltrate water into the top of the overlying rock area, and inflate and deflate the gas storage tank inside the lining structure model, recording the parameters obtained by the detection elements. The inner surface of the lining structure model is provided with a sealing layer, and the inner surface of the sealing layer is provided with distributed optical fibers and stress gauges as detection elements of the inner surface of the lining structure model. The sealing component is a concrete air plug cast at the end of the lining structure model, with one end of the concrete air plug having an air inlet and an air outlet. A water tank is placed on top of the overlying rock area. The tank contains water and has a water inlet on the bottom wall to allow water to flow into the overlying rock area.

2. The test method for a compressed air storage tank in a coal roadway as described in claim 1, characterized in that, The sealing layer includes a first sealing layer located on the inner surface of the lining structure model and a second sealing layer located on the surface of the first sealing layer. The first sealing layer is made of phenolic foam material, B1 grade polyurethane spray insulation material, or foamed cement, and the second sealing layer is made of steel plate, butyl rubber, EPDM rubber, natural rubber, or fiberglass.

3. The test method for a compressed air storage tank in a coal roadway as described in claim 1, characterized in that, For horizontal or at a set acute angle to the horizontal fracture layer, first fill the surrounding rock block below it, then place the fracture template on top of the filled surrounding rock block and compact it to form a surface along the shape of the fracture, then remove the fracture template, lay a fracture-like material to form a fracture layer, and then fill the surrounding rock block above the fracture layer. For vertical fracture layers, first place a fracture template, then fill the surrounding rock blocks on both sides of the fracture template, remove the fracture template, and blow in fracture-like materials to form a fracture layer.

4. The test method for a compressed air storage tank in a coal roadway as described in claim 1, characterized in that, When filling the surrounding rock damage zone, all surrounding rock blocks are filled, and crack templates are set between adjacent surrounding rock blocks. Then, along the longitudinal direction of the lining structure model, the crack templates are pulled out from one side while crack-like materials are blown in from the other side.

5. The test method for a compressed air storage tank in a coal roadway as described in claim 1, characterized in that, During the filling of the surrounding rock damage zone, all surrounding rock blocks are filled, and crack templates are set between adjacent surrounding rock blocks. The crack templates are made of water-soluble support material. Holes are drilled into the crack templates and water is injected, causing the crack templates to gradually dissolve. At the same time, crack-like materials are blown in.

6. The test method for a compressed air storage tank in a coal roadway as described in claim 1, characterized in that, An expansion membrane bag is installed between the concrete air plug and the inner side of the end of the lining structure model. After the concrete air plug is poured, cement-water glass quick-setting grout is injected into the expansion membrane bag. After the expansion membrane bag expands, it seals the concrete air plug and the inner side of the lining structure model.

7. The test method for a compressed air storage tank in a coal roadway as described in claim 1, characterized in that, The air is circulated into the lining structure model through an air inflation / deflation mechanism. The air inflation / deflation mechanism includes a compressed air supply element, which is connected to one end of an air inlet pipe. The other end of the air inlet pipe extends into the interior space of the lining structure model through an air inlet hole. An air outlet pipe is fixed at the air outlet hole, which connects the interior space of the lining structure model with the exterior space. Both the air inlet pipe and the air outlet pipe are equipped with valves.

8. The test method for a compressed air storage tank in a coal roadway as described in claim 1, characterized in that, The detection elements inside the surrounding rock block are multiple piezometers and stress gauges.

9. The test method for a compressed air storage tank in a coal roadway as described in claim 1, characterized in that, The water tank is equipped with a heating element.

Images