Gas storage sealing structure physical model test system and construction method thereof

Abstract

The invention discloses a gas storage sealing structure physical model test system and a construction method thereof. The system comprises an external concrete test block, a middle deformation and support simulation layer and an internal gas storage chamber, the deformation and support simulation layer comprises one or more groups of sand bodies with different gradations and different porosities arranged around the gas storage chamber, rock bodies with faults, excavation disturbance and various surrounding rock grades are simulated through the sand bodies, a surrounding rock progressive support effect is conveniently applied, and the deformation and support simulation effect is achieved. A multi-point displacement meter and a strain block which are used for detecting stress deformation of the sand body are embedded in the sand body; the gas storage chamber is communicated with a gas inlet pipeline and a gas outlet pipeline; and an air inlet of the air inlet pipeline is connected with an air compressor. According to the method, the temperature, humidity, pressure and displacement change conditions of the underground gas storage in each stage of gas inflation, gas storage and gas deflation under the condition that the surrounding rock pressure load of the excavation disturbance surface is considered are reflected more truly and comprehensively.

Description

Technical Field

[0001] The present invention relates to the technical field of underground energy storage, and particularly to a physical model test system for a gas storage cavern sealing structure and a construction method thereof. Background Art

[0002] Compressed air energy storage has been demonstrated by domestic and foreign experts and is considered to be the most promising long-term and efficient energy storage method in the future. At present, for the compressed air energy storage power stations put into operation at home and abroad, the underground gas storage caverns are all salt caverns. However, there are certain limitations in the distribution of domestic salt mines, and a large number of power load center cities do not have the corresponding construction conditions. Therefore, it is an inevitable choice to use artificial chambers to replace salt caverns as gas storage caverns. Under this background, a large number of experts and scholars have studied artificial chambers.

[0003] The main focus of the existing indoor physical model tests of artificial chambers is on the selection of sealing materials and the construction of sealing structures, and certain achievements have been made in relevant tests. Many physical tests have studied the changes in the internal sealing layer and external surrounding rock of the gas storage cavern during different stages of gas charging, gas storage, and gas discharge by making a scaled-down gas storage cavern.

[0004] In the prior art, concrete test blocks are directly used as the surrounding rock in indoor physical model tests. However, in actual engineering, the stress balance of the original rock mass in this area is often broken during the excavation of the chamber. Near the excavation surface, the rock mass may undergo shear failure or plastic deformation. If concrete test blocks are directly used as the surrounding rock, then the consideration of the excavation disturbance surface and fault structural planes will be lacking, resulting in a large pressure exerted by the concrete test blocks directly on the experimental object, lacking the progressive support effect of the rock stratum on the gas storage cavern chamber, and there is a certain difference between the conclusions obtained and the actual situation. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a physical model test system for a gas storage cavern sealing structure and a construction method thereof, which can effectively simulate the physical model test system of a gas storage cavern sealing structure with different surrounding rock support effects, and more truly and comprehensively reflect the temperature, humidity, pressure, and displacement changes in each stage of gas charging, gas storage, and gas discharge of the underground gas storage cavern under the surrounding rock pressure load considering the excavation disturbance surface, so as to more accurately determine the sealing performance and stability of the gas storage cavern sealing layer.

[0006] To achieve the above object, a physical model test system for a gas storage cavern sealing structure designed by the present invention is used to conveniently apply the progressive support effect of the surrounding rock under different rock mass conditions, and can simulate different excavation damage zones and local weak zones between different faults. It includes an external concrete test block and an internal gas storage cavern chamber, and is particularly characterized in that: a deformation and support simulation layer is provided between the gas storage cavern chamber and the concrete test block;

[0007] The gas storage chamber comprises a sealing layer arranged inside the cavity, and a concrete lining layer is arranged on the periphery of the sealing layer; a longitudinal optical fiber sensor and a circumferential optical fiber sensor for detecting strain, displacement, temperature, and humidity changes at different positions are attached to the outside of the sealing layer; the longitudinal optical fiber sensor and the circumferential optical fiber sensor extension section are connected to a control system located outside the concrete test block;

[0008] The deformation and support simulation layer includes one or more groups of sand bodies with different gradations and porosities arranged around the gas storage chamber, and the sand bodies are used to simulate the presence or absence of faults, excavation disturbances and rock bodies of various surrounding rock grades, so as to conveniently exert the progressive support effect of the surrounding rock. Multi-point displacement meters and strain blocks for detecting the stress deformation of the sand bodies are buried in the sand bodies;

[0009] The top of the gas storage chamber is connected to an air inlet pipe extending to the outside of the concrete test block, and the bottom of the gas storage chamber is connected to an air outlet pipe extending to the outside of the concrete test block;

[0010] The air inlet of the air inlet pipeline is connected with an air compressor, and the air compressor, the multi-point displacement meter and the strain block are respectively connected with the control system.

[0011] Furthermore, a cylindrical steel bar mesh is pre-buried inside the concrete lining layer, and the steel bar mesh includes a plurality of longitudinal steel bars and annular steel bars formed by binding.

[0012] Furthermore, a cubic steel mesh for applying ground stress is pre-embedded inside the concrete test block, and the cubic steel mesh includes a plurality of transverse prestressed steel bars, longitudinal prestressed steel bars, and axial prestressed steel bars formed by binding, and both ends of each transverse prestressed steel bar, longitudinal prestressed steel bar, and axial prestressed steel bar extend to the outside of the concrete test block.

[0013] Furthermore, the gas storage chamber is placed inside the cubic steel mesh. The tensioning force of each steel bar is adjusted according to the actual ground stress conditions. The concrete test block is deformed by the steel bars, and the stress, strain and displacement are transmitted to the gas storage chamber, thereby simulating the ground stress acting on the gas storage chamber in different directions and at different depths.

[0014] Furthermore, the sand body gradation is set according to different excavation disturbance layers and surrounding rock fault conditions.

[0015] Furthermore, the sealing layer is in the shape of a cylinder which is connected and sealed at both ends.

[0016] Furthermore, the air inlet pipe and the air outlet pipe are composed of high-pressure steel pipes.

[0017] Furthermore, an air intake valve is provided at the inlet of the air intake pipe, and an air intake pressure gauge is provided between the air intake valve and the gas storage chamber; an air outlet valve is provided at the outlet of the air outlet pipe, and an air outlet pressure gauge is provided between the air outlet valve and the gas storage chamber.

[0018] The present invention also provides a method for constructing a physical model test system for a gas storage reservoir sealing structure, which is applicable to the above-mentioned physical model test system for a gas storage reservoir sealing structure, and is particularly characterized in that it comprises the following steps:

[0019] S1) preparing a gas storage chamber;

[0020] S2) Tie out the cubic steel mesh in the concrete test block;

[0021] S3) pouring a cubic steel mesh from bottom to top to the height of the top of the gas storage chamber, and retaining a vertical reserved cavity inside the cubic steel mesh for burying the gas storage chamber and the deformation and support simulation layer; fixing the cast body; then modulating the sand body according to the designed gradation, filling and vibrating and compacting it in the reserved space in layers, when the sand body material at the bottom is filled, placing the prepared gas storage chamber in the middle of the reserved space, continuing to fill and compact the sand body in layers, and burying a multi-point displacement meter and a strain block inside the sand body; after the sand body is filled, pouring the remaining part on the top of the cubic steel mesh, curing and demoulding, to form a complete concrete test block;

[0022] S4) connecting one end of the air inlet pipe to the top of the gas storage chamber, and the other end to the air compressor; connecting the longitudinal optical fiber sensor and the circumferential optical fiber sensor to the control system; connecting one end of the air outlet pipe to the bottom of the gas storage chamber;

[0023] S5) Apply prestress on the cubic steel mesh to simulate ground stress; turn on the air compressor, and inject compressed gas into the gas storage chamber through the air inlet pipe, control the inflation, deflation, and gas storage time of a single test, and record the stress, displacement, temperature, and humidity changes of the gas storage chamber at different stages and positions through the test, and then judge the overall stability of the gas storage structure and the stability of the sealing layer based on the corresponding data.

[0024] Furthermore, in S1), the specific steps of preparing the gas storage chamber are as follows:

[0025] Connect the sealing layer into a circular tube shape, and paste longitudinal fiber optic sensors and circumferential fiber optic sensors around the outer side and at both ends of the sealing layer; then place the sealing layer in a specific cylindrical mold, and place a fixing device inside the tubular sealing layer to prevent the structure from deforming; secondly, insert longitudinal steel bars into the gap between the specific cylindrical mold and the sealing layer and tie them with circumferential steel bars to form a steel bar network; finally, fill the gap between the specific cylindrical mold and the sealing layer with concrete. After curing and demolding, a concrete lining layer with a sealing layer on the inner wall is formed to constitute the gas storage cavern.

[0026] The advantages of the present invention are as follows:

[0027] 1. Compared with the existing physical model tests, on the basis of loading the external surrounding rock stress load into the gas storage system, the present invention safely, simply, effectively and economically takes into account the influence of the excavation disturbed surface, faults and surrounding rock grades on the sealing performance and stability of the gas storage, and can more truly reflect the overall structural stability of the gas storage under the coupling action of internal and external loads in the actual state, as well as the interference of the gas charging and discharging process of the gas storage on the external surrounding rock, and determines the sealing performance and stability of the sealing layer of the gas storage by collecting various sensor data;

[0028] 2. The present invention sets a deformation and support simulation layer composed of sand bodies with different gradations and porosities between the gas storage cavern and the concrete test block to simulate different rock deformation and support capabilities, the excavation disturbed surfaces of different underground surrounding rock faults, and the locally weak areas between different faults, and more truly and comprehensively studies the sealing performance and stability of the sealing structure of the gas storage under the support of deformed surrounding rock;

[0029] 3. Ideally, the sealing layer inside the gas storage is not stressed, but due to the different elastic moduli of the sealing layer and the concrete, it will bear a part of the force. There will be a contact layer at the connection of the sealing layer, and the force inside the gas storage is not necessarily uniform. The sealing layer structure in the present invention adopts the installation method of the actual sealing layer of the gas storage, and connects the sheet-shaped sealing layer to form a cylindrical shape with both ends sealed, which can more accurately reflect the stability of the sealing layer structure in the actual gas storage;

[0030] 4. The present invention can greatly reduce the cost compared with the actual cavern simulation and is not limited by hydrogeological conditions; compared with the existing physical test model system, it can more truly and accurately reflect the actual working conditions of the gas storage;

[0031] The physical model test system for the gas storage reservoir sealing structure of the present invention and its construction method use sand as the filling material for simulating the excavation disturbed surface, taking into account the effects of the excavation disturbed surface, faults, and surrounding rock grades on the sealing and stability of the gas storage reservoir, and more realistically and comprehensively reflecting the temperature, humidity, pressure, and displacement changes during the inflation, gas storage, and gas release stages of the underground gas storage reservoir under the surrounding rock pressure load considering the excavation disturbed surface, so as to more accurately determine the sealing and stability of the sealing layer of the gas storage reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of the physical model test system for the gas storage reservoir sealing structure in the present invention;

[0033] Figure 2 It is a schematic internal structure diagram of the gas storage reservoir chamber in the present invention;

[0034] Figure 3 It is the cubic steel bar mesh inside the concrete test block in the present invention;

[0035] Figure 4 It is a schematic sectional view of the overall test specimen in the present invention;

[0036] Figure 5 It is a schematic diagram of the cross section of the test specimen in the present invention;

[0037] Figure 6 It is a flow chart of the construction method of the physical model test system for the gas storage reservoir sealing structure in the present invention;

[0038] Figure 7 It is a schematic diagram of the filling, vibrating, and pouring sequence in the present invention;

[0039] Figure 8 It is a schematic diagram of filling the sand body and pouring the concrete test block in the present invention;

[0040] In the figure: air compressor 1, deformation and support simulation layer 2, gas storage reservoir chamber 3, concrete test block 4, control system 5, intake pipe 6, outlet pipe 7, fixed arm 8, vibrating table 9;

[0041] The deformation and support simulation layer 2 includes: multi-point displacement gauges and strain gauges 2-1;

[0042] The gas storage reservoir chamber 3 includes: sealing layer 3-1, concrete lining layer 3-2, longitudinal steel bars 3-3, circumferential steel bars 3-4, longitudinal fiber optic sensors 3-5, circumferential fiber optic sensors 3-6;

[0043] The concrete test block 4 includes: transverse prestressed steel bars 4-1, longitudinal prestressed steel bars 4-2, axial prestressed steel bars 4-3;

[0044] The intake pipeline 6 includes: an intake valve 6-1 and an intake manometer 6-2;

[0045] The outlet pipeline 7 includes: an outlet valve 7-1 and an outlet manometer 7-2. Specific implementation manners

[0046] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0047] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, 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 thus should not be construed as a limitation to the invention.

[0048] As Figures 1 to 5 shown, a physical model test system for a gas storage cavern sealing structure of the present invention is used to conveniently apply progressive support to the surrounding rock under different rock mass conditions, and can simulate different excavation damage zones and local weak zones between different faults. It includes an external concrete test block 4 and an internal gas storage cavern 3, and a deformation and support simulation layer 2 is provided between the gas storage cavern 3 and the concrete test block 4.

[0049] The gas storage cavern 3 includes a sealing layer 3-1 provided inside the cavity, and a concrete lining layer 3-2 is provided on the outer periphery of the sealing layer 3-1; longitudinal optical fiber sensors 3-5 and circumferential optical fiber sensors 3-6 for detecting changes in strain, displacement, temperature, and humidity at different positions are pasted on the outer side of the sealing layer 3-1; the extending sections of the longitudinal optical fiber sensors 3-5 and the circumferential optical fiber sensors 3-6 are connected to a control system 5 located outside the concrete test block 4.

[0050] Specifically, the pressure change range in the gas storage cavern 3 is 6-18 MPa, which is used to simulate an actual gas storage cavern.

[0051] Specifically, the sealing layer 3-1 is cylindrical and formed by connection with both ends sealed. In an ideal state, the sealing layer inside the gas storage is not stressed, but due to the different elastic moduli of the sealing layer and the concrete, the sealing layer in the actual gas storage may bear a part of the force, especially the force at the connection position of the sealing layer is not necessarily uniform. The gas storage cavern in the present invention adopts the installation method of the actual gas storage sealing layer, and connects the sheet-shaped sealing layer to form a cylindrical shape with both ends sealed, which can more accurately reflect the stability of the sealing layer structure in the actual gas storage.

[0052] Specifically, a cylindrical steel bar network is embedded inside the concrete lining layer 3-2. The steel bar network includes a plurality of longitudinal steel bars 3-3 and circumferential steel bars 3-4 formed by binding. The longitudinal steel bars 3-3 extend along the axis of the gas storage chamber 3 and are arranged at intervals around the circumference of the gas storage chamber 3. The circumferential steel bars 3-4 are arranged at intervals along the axis of the gas storage chamber 3.

[0053] The longitudinal fiber optic sensors 3-5 and the circumferential fiber optic sensors 3-6 include stress sensors, strain sensors, displacement sensors, and temperature sensors.

[0054] The deformation and support simulation layer 2 includes one or more groups of sand bodies with different gradations and porosities arranged around the gas storage chamber 3. The sand bodies are used to simulate rock masses with or without faults, excavation disturbances, and various surrounding rock grades, and the progressive support effect of the surrounding rock can be conveniently applied. Multi-point displacement gauges and strain gauges 2-1 for detecting the stress and deformation of the sand bodies are embedded in the sand bodies.

[0055] Specifically, the gradation of the sand bodies is set according to different excavation disturbance layers and surrounding rock fault conditions.

[0056] Specifically, a cubic steel bar network for applying in-situ stress is embedded inside the concrete test block 4. The cubic steel bar network includes a plurality of transverse prestressed steel bars 4-1, longitudinal prestressed steel bars 4-2, and axial prestressed steel bars 4-3 formed by binding. The two ends of each of the transverse prestressed steel bars 4-1, longitudinal prestressed steel bars 4-2, and axial prestressed steel bars 4-3 extend to the outside of the concrete test block 4.

[0057] Preferably, the transverse prestressed steel bars 4-1, longitudinal prestressed steel bars 4-2, and axial prestressed steel bars 4-3 are in three mutually perpendicular directions.

[0058] Specifically, the spacing between adjacent transverse prestressed steel bars 4-1, longitudinal prestressed steel bars 4-2, and axial prestressed steel bars 4-3 in the same direction is 20 - 40 cm.

[0059] The concrete in the concrete lining layer 3-2 is C40 high-strength concrete, and the concrete in the concrete test block 4 is C40 high-strength concrete.

[0060] Specifically, the gas storage chamber 3 is placed inside the cubic steel bar network. The tensile force of each steel bar is adjusted according to the actual in-situ stress situation. The concrete test block 4 is deformed by the steel bars, and the stress, strain, and displacement are transmitted to the gas storage chamber 3, so as to simulate the in-situ stress acting on the gas storage chamber 3 in different directions and at different depths.

[0061] The top end of the gas storage chamber 3 is connected to an intake pipe 6 that extends outside the concrete test block 4, and the bottom end of the gas storage chamber 3 is connected to an outlet pipe 7 that extends outside the concrete test block 4.

[0062] Specifically, the intake pipe 6 and the outlet pipe 7 are composed of high-pressure steel pipes.

[0063] Specifically, an intake valve 6-1 is provided at the inlet of the intake pipe 6, and an intake pressure gauge 6-2 is provided between the intake valve 6-1 and the gas storage chamber 3; an outlet valve 7-1 is provided at the outlet of the outlet pipe 7, and an outlet pressure gauge 7-2 is provided between the outlet valve 7-1 and the gas storage chamber 3.

[0064] The air inlet of the intake pipe 6 is connected to an air compressor 1, and the air compressor 1, the multi-point displacement gauge, and the strain gauge 2-1 are respectively connected to the control system 5.

[0065] Compared with the existing physical model tests, on the basis of loading the external surrounding rock stress load onto the gas storage system, the present invention safely, simply, effectively, and economically takes into account the effects of the excavation disturbance surface, faults, and surrounding rock grades on the gas storage tightness and stability, and can more realistically reflect the overall structural stability of the gas storage under the coupling action of internal and external loads in the actual state, as well as the interference of the gas storage charging and discharging processes on the external surrounding rock. By collecting various sensor data, the tightness and stability of the gas storage sealing layer are determined. Specifically, the present invention simulates different rock deformation and support capabilities, the excavation disturbance surfaces of different underground surrounding rock faults, and the locally weak areas between different faults by arranging a deformation and support simulation layer composed of sand bodies with different gradations and porosities between the gas storage chamber and the concrete test block, and more realistically and comprehensively studies the tightness and stability of the gas storage sealing structure under the support of the deformed surrounding rock.

[0066] In the system of the present invention, the air compressor 1 presses high-pressure air into the gas storage chamber 3 through the intake pipeline 6 and the outlet pipeline 7. The gas storage system consists of three parts: the external part is composed of high-strength prestressed concrete test blocks 4 formed by pouring prestressed steel bars arranged in the longitudinal, transverse, and axial directions. The tensile force of each steel bar is adjusted according to the actual in-situ stress conditions, and the concrete is deformed by the steel bars to transmit the force to the test specimen, thereby simulating the in-situ stresses acting on the gas storage chamber 3 in different directions and at different depths; the middle part is the deformation and support simulation layer 2, which can be filled with one or more groups of sand bodies with different gradations according to different surrounding rock excavation and fault conditions. Multi-point displacement gauges and strain gauges 2-1 are buried in the sand bodies; the internal part is composed of the gas storage chamber 3, which includes a sealing layer 3-1 and a concrete lining layer 3-2. The concrete lining layer 3-2 is a hollow cylindrical structure, and the lining contains axial steel bars and circumferential stirrups. The internal pressure of the gas storage chamber 3 will be transmitted to the deformation and support simulation layer 2 through the concrete lining layer 3-2, and then transmitted to the external concrete test block 4 by the deformation and support simulation layer 2. The temperature, humidity, pressure, and displacement changes at both ends and all positions around the sealing layer 3-1 during the inflation, gas storage, and deflation stages are transmitted to the computer for recording through corresponding sensors.

[0067] Compared with the actual cavern simulation, the present invention can greatly reduce costs and is not restricted by hydrogeological conditions; compared with the existing physical test model system, it can more truly reflect the actual working conditions of the gas storage.

[0068] Before the test, it is necessary to complete the production of the gas storage system simulation device. The present invention also designs a construction method for the physical model test system of the gas storage sealing structure, which is applicable to the above-mentioned physical model test system of the gas storage sealing structure, such as Figure 6 shown, including the following steps:

[0069] S1) Prepare the gas storage chamber 3. Specifically, the specific steps for preparing the gas storage chamber 3 are as follows:

[0070] Connect the sealing layer 3-1 into a circular tubular shape, and paste longitudinal optical fiber sensors 3-5 and circumferential optical fiber sensors 3-6 around the outside and at both ends of the sealing layer 3-1; then place the sealing layer 3-1 in a specific cylindrical mold, and place a fixing device inside the tubular sealing layer 3-1 to prevent the structure from deforming; secondly, insert longitudinal steel bars 3-3 into the gap between the specific cylindrical mold and the sealing layer 3-1 and tie them with circumferential steel bars 3-4 to form a steel bar network; finally, fill the gap between the specific cylindrical mold and the sealing layer 3-1 with concrete. After curing and demolding, a concrete lining layer 3-2 with the sealing layer 3-1 on the inner wall is formed, constituting the gas storage chamber 3.

[0071] S2) Bind the cubic steel bar network in the concrete test block 4.

[0072] High-strength and high-toughness steel bars are used and arranged at equal intervals in the transverse, longitudinal, and axial directions to form a cubic steel bar mesh by binding. The distance between adjacent steel bars in the same direction is 20 cm to 40 cm, and sufficient lengths are reserved at both ends of the steel bars.

[0073] S3) Pour the cubic steel bar mesh from the bottom upwards until reaching the height at the top of the gas storage chamber 3, and reserve a vertical reserved cavity inside the cubic steel bar mesh for embedding the gas storage chamber 3 and the deformation and support simulation layer 2; fix the poured body; then modulate the sand body according to the designed grading, and fill and vibrate and compact it in layers in the reserved space. After the sand body material at the bottom is filled, place the prepared gas storage chamber 3 in the middle of the reserved space, continue to fill and compact the sand body in layers, and embed multi-point displacement gauges and strain gauges 2-1 inside the sand body; after the sand body filling is completed, pour the remaining part on top of the cubic steel bar mesh, cure and demold to form a complete concrete test block 4.

[0074] As Figure 7 shown, in this embodiment, the concrete block 4 is fixed by the fixed arm 8, as in sequence a; fill the first group of sand in layers and complete compaction and uniform sand body under the vibration of the vibrating table 9, as in sequence b; repeat the steps to complete the filling of the deformation and support simulation layer 2, as in sequence c; finally complete the filling of the remaining part of the concrete block 4.

[0075] Specifically, as Figure 8 shown, the deformation and support simulation layer 2 evenly grades the filling material and then lays, compacts, and vibrates it in layers, as in sequences a to c; the concrete test block 4 is poured in batches, reserving a certain space inside the outermost layer of the reserved excavation disturbance surface. After the filling material is filled, pour the unfinished part at the top, as in sequences d to e.

[0076] S4) Connect one end of the intake pipe 6 to the top of the gas storage chamber 3 and the other end to the air compressor 1; connect the longitudinal fiber optic sensor 3-5 and the circumferential fiber optic sensor 3-6 to the control system 5; connect one end of the outlet pipe 7 to the bottom of the gas storage chamber 3.

[0077] S5) Apply prestress on the cubic steel bar mesh to simulate the in-situ stress; turn on the air compressor 1, and inject compressed gas into the gas storage chamber 3 through the intake pipe 6. Control the inflation, deflation, and gas storage time for each test, record the stress, displacement, temperature, and humidity changes of the gas storage chamber 3 at different stages and different positions through the test, and then judge the overall stability of the gas storage structure and the stability of the sealing layer based on the corresponding data.

[0078] Specifically, apply prestress on the transverse, axial, and longitudinal steel bars to simulate the in-situ stress.

[0079] The physical model test system for the gas storage reservoir sealing structure of the present invention and its construction method use sand as the filling material for simulating the excavated disturbed surface, taking into account the influences of the excavated disturbed surface, faults and surrounding rock grades on the sealing performance and stability of the gas storage reservoir, and more truly and comprehensively reflecting the temperature, humidity, pressure and displacement changes in each stage of gas filling, gas storage and gas release of the underground gas storage reservoir under the surrounding rock pressure load considering the excavated disturbed surface, so as to more accurately determine the sealing performance and stability of the sealing layer of the gas storage reservoir.

[0080] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A physical model test system for a gas storage reservoir sealing structure, used to simulate the gradual support effect of surrounding rocks under different rock mass conditions, and capable of simulating different excavation damage zones and local weak zones between different faults, comprising an external concrete test block (4) and an internal gas storage reservoir chamber (3), characterized in that: A deformation and support simulation layer (2) is provided between the gas storage chamber (3) and the concrete test block (4); The gas storage chamber (3) comprises a sealing layer (3-1) arranged inside the cavity, and a concrete lining layer (3-2) is arranged on the periphery of the sealing layer (3-1); longitudinal optical fiber sensors (3-5) and circumferential optical fiber sensors (3-6) for detecting strain, displacement, temperature, and humidity changes at different positions are attached to the outside of the sealing layer (3-1); the extension sections of the longitudinal optical fiber sensors (3-5) and circumferential optical fiber sensors (3-6) are connected to a control system (5) located outside the concrete test block (4); The deformation and support simulation layer (2) comprises one or more groups of sand bodies with different gradations and porosities arranged around the gas storage chamber (3), and the sand bodies are used to simulate the presence or absence of faults, excavation disturbances and rock bodies of various surrounding rock grades, so as to conveniently exert the surrounding rock progressive support effect. A multi-point displacement meter and a strain block (2-1) for detecting the stress deformation of the sand bodies are buried in the sand bodies; The top end of the gas storage chamber (3) is connected to an air inlet pipe (6) extending to the outside of the concrete test block (4), and the bottom end of the gas storage chamber (3) is connected to an air outlet pipe (7) extending to the outside of the concrete test block (4); The air inlet of the air inlet pipeline (6) is connected to an air compressor (1), and the air compressor (1), the multi-point displacement meter and the strain block (2-1) are respectively connected to the control system (5).

2. The physical model test system for the gas storage sealing structure according to claim 1 is characterized by: A cylindrical steel bar network is pre-buried inside the concrete lining layer (3-2), and the steel bar network includes a plurality of longitudinal steel bars (3-3) and annular steel bars (3-4) formed by binding.

3. The physical model test system for the gas storage sealing structure according to claim 2 is characterized by: A cubic steel mesh for applying ground stress is pre-buried inside the concrete test block (4), the cubic steel mesh comprising a plurality of transverse prestressed steel bars (4-1), longitudinal prestressed steel bars (4-2), and axial prestressed steel bars (4-3) formed by binding, and both ends of each transverse prestressed steel bar (4-1), longitudinal prestressed steel bar (4-2), and axial prestressed steel bar (4-3) extend to the outside of the concrete test block (4).

4. The physical model test system for the gas storage sealing structure according to claim 3 is characterized by: The gas storage chamber (3) is placed inside a cubic steel mesh, and the tension of each steel bar is adjusted according to the actual ground stress. The concrete test block (4) is deformed by the steel bars, and the stress, strain and displacement are transmitted to the gas storage chamber (3), thereby simulating the ground stress acting on the gas storage chamber (3) in different directions and at different depths.

5. The physical model test system for the gas storage sealing structure according to claim 4 is characterized in that: The sand body gradation is set according to different excavation disturbance layers and surrounding rock fault conditions.

6. The physical model test system for the gas storage sealing structure according to claim 1 is characterized by: The sealing layer (3-1) is in the shape of a cylinder which is connected and sealed at both ends.

7. The physical model test system for the gas storage sealing structure according to claim 6 is characterized by: The air inlet pipe (6) and the air outlet pipe (7) are composed of high-pressure steel pipes.

8. The physical model test system for the gas storage sealing structure according to claim 1 is characterized by: The inlet of the air inlet pipeline (6) is provided with an air inlet valve (6-1), and an air inlet pressure gauge (6-2) is provided between the air inlet valve (6-1) and the gas storage chamber (3); the outlet of the air outlet pipeline (7) is provided with an air outlet valve (7-1), and an air outlet pressure gauge (7-2) is provided between the air outlet valve (7-1) and the gas storage chamber (3).

9. A method for constructing a physical model test system for a gas storage reservoir sealing structure, applicable to the physical model test system for a gas storage reservoir sealing structure as claimed in claims 1 to 8, characterized in that: The steps include: S1) preparing a gas storage chamber (3); S2) tying the cubic steel mesh in the concrete test block (4); S3) pouring a cubic steel mesh from bottom to top to the height of the top of the gas storage chamber (3), and retaining a vertical reserved cavity inside the cubic steel mesh for burying the gas storage chamber (3) and the deformation and support simulation layer (2); fixing the cast body; then modulating the sand body according to the designed gradation, filling and vibrating and compacting it in the reserved space in layers, and when the sand body material at the bottom is filled, placing the prepared gas storage chamber (3) in the middle of the reserved space, continuing to fill and compact the sand body in layers, and burying a multi-point displacement meter and a strain block (2-1) inside the sand body; after the sand body is filled, pouring the remaining part on the top of the cubic steel mesh, curing and demoulding, to form a complete concrete test block (4); S4) connecting one end of the air inlet pipe (6) to the top of the gas storage chamber (3), and the other end to the air compressor (1); connecting the longitudinal optical fiber sensor (3-5) and the circumferential optical fiber sensor (3-6) to the control system (5); connecting one end of the air outlet pipe (7) to the bottom of the gas storage chamber (3); S5) applying prestress on the cubic steel mesh to simulate ground stress; turning on the air compressor (1), injecting compressed gas into the gas storage chamber (3) through the air inlet pipe (6), controlling the inflation, deflation and gas storage time of a single test, recording the stress, displacement, temperature and humidity changes of the gas storage chamber (3) at different stages and positions through the test, and then judging the overall stability of the gas storage structure and the stability of the sealing layer based on the corresponding data.

10. The method for constructing a physical model test system for a gas storage sealing structure according to claim 9, characterized in that: In S1), the specific steps of preparing the gas storage chamber (3) are as follows: The sealing layer (3-1) is connected into a circular tube, and longitudinal optical fiber sensors (3-5) and circumferential optical fiber sensors (3-6) are attached around the outside and at both ends of the sealing layer (3-1); then the sealing layer (3-1) is placed in a specific cylindrical mold, and a fixing device is placed inside the tubular sealing layer (3-1) to prevent the structure from deforming; secondly, longitudinal steel bars (3-3) are inserted into the gap between the specific cylindrical mold and the sealing layer (3-1) and are tied with circumferential steel bars (3-4) to form a steel pipe network; finally, concrete is filled in the gap between the specific cylindrical mold and the sealing layer (3-1), and after curing and demoulding, a concrete lining layer (3-2) with the sealing layer (3-1) on the inner wall is formed to constitute a gas storage chamber (3).

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