Sealing plug, underground gas storage and construction method of underground gas storage

Abstract

The invention provides a sealing plug, an underground gas storage and a construction method of the underground gas storage. The sealing plug comprises a body, a force bearing structure arranged outside the body in a sleeving mode and a retaining wall arranged on one axial end side of the body and the force bearing structure, the body is a cone frustum, the force bearing structure is provided with a first layer and a second layer from inside to outside, the first layer is attached to the outer surface of the body, and the second layer is attached to the outer surface of the body. A first contact surface and a second contact surface are arranged on the outer surface of the second layer, and an included angle is formed between the first contact surface and the second contact surface in the axial direction of the body. The sealing plug is designed to be of a variable cross-section structure, so that the sealing plug meets the requirements of high pressure, cyclic load and cyclic impact under the operation condition of the gas storage, the risk of structural instability is reduced, and the sealing plug is simple in structure, convenient to construct and higher in reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed air energy storage, and in particular to a sealing plug, an underground gas storage and a construction method thereof. Background Art

[0002] Compressed air energy storage is a technology that uses compressed air as a medium to store energy and generate electricity. Currently, underground caverns such as salt caverns and artificially excavated caverns are commonly used as gas storage containers. Among them, rock-lined caverns can be built in widely distributed hard rock formations, with more freedom in site selection, and are suitable for large-scale promotion.

[0003] With the increase in current installed capacity and operating efficiency requirements, the design pressure of gas storage is as high as 10-20MPa, and the filling and discharging process will generate cyclic pressure and temperature loads. As a key component of the gas storage, the sealing plug is a direct plugging and bearing structure for the high-pressure gas in the artificial underground gas storage, and as a connecting part for important pipelines and channels, it is a key structure that affects the safety and efficiency of the gas storage operation.

[0004] Existing sealing plug structures, such as the underground gas storage overpressure relief and alarm system for compressed air energy storage disclosed in Patent Publication No. CN117537265A, have sealing plugs at the opening of the gas storage, and the sealing plugs are of equal cross-section structure. At present, the air pressure inside the artificial underground gas storage chamber is much higher than the head pressure of the hydraulic tunnel, and the layout of the inspection channel and the compressed air duct needs to be considered. The design idea of ​​the gas storage sealing plug structure is to combine the inspection channel and the compressed air pipeline into the same channel. Therefore, at the sealing plug part, the cross-section of the channel for gas circulation during the filling and deflation process undergoes two changes: gas storage cavern-inspection channel, inspection channel-filling and deflation pipeline. The change in channel cross-section will cause a sudden change in the air flow rate. The use of the above-mentioned existing sealing plugs will cause the sealing plug part to frequently bear large impact loads, posing a greater threat to the structural stability and service life of the sealing plug. Summary of the invention

[0005] The object of the present invention is to provide a sealing plug, an underground gas storage and a construction method thereof, to optimize the sealing plug structure, to meet the requirements of high pressure, cyclic load and cyclic impact under the operating conditions of the gas storage, and to reduce the risk of structural instability.

[0006] The technical solution of the present invention is: a sealing plug, comprising a main body, a load-bearing structure mounted on the outside of the main body, and a retaining wall arranged on one axial end side of the main body and the load-bearing structure, the main body is a frustum, the load-bearing structure is provided with a first layer and a second layer from the inside to the outside, the first layer is attached to the outer surface of the main body, the outer surface of the second layer is provided with a first contact surface and a second contact surface, the first contact surface and the second contact surface have an angle in the axial direction of the main body.

[0007] In the above scheme, the sealing plug is designed to have a main body with a truncated cone and a load-bearing structure with a first contact surface and a second contact surface, and the first contact surface and the second contact surface have an angle in the axial direction of the main body. Therefore, the sealing plug is designed to have a variable cross-section structure, and the load-bearing structure of a negative Poisson's ratio material is used to achieve a negative Poisson's ratio effect, so that the sealing plug not only meets the high pressure, cyclic load, and cyclic impact requirements under the operating conditions of the gas storage reservoir, and reduces the risk of structural instability, but also has a simple structure, convenient construction, and higher reliability.

[0008] The negative Poisson's ratio effect means that when stretched, the material expands laterally within the elastic range; when compressed, the material contracts laterally. Negative Poisson's ratio materials have excellent elastic modulus, shear modulus, energy absorption and resilience due to their negative Poisson's ratio effect. The elastic modulus E and shear modulus G of the material are closely related to the Poisson's ratio v. There is a relationship between the shear modulus G and the elastic modulus E and the Poisson's ratio μ: G=E / (2(1+μ)). When the Poisson's ratio changes from positive to negative, the shear resistance is significantly improved. As a result, the sealing plug has the characteristics of expanding laterally within the elastic range when stretched, and contracting laterally when compressed.

[0009] Preferably, the first layer is provided with endpoints A and B at both ends of the axial direction, and the body is provided with endpoints C and D at both ends, the vertical distance between endpoints A and C is d1, the vertical distance between endpoints B and D is d2, and d2≥d1. This structural design can ensure that the body transfers most of the pressure load to the load-bearing structure, and the maximum shear stress area of ​​the sealing plug is located inside the load-bearing structure as much as possible, so that the load-bearing structure bears the main shear stress of the body.

[0010] Preferably, the end point A is formed with a diameter L1, the retaining wall has a diameter L2, L1≥L2, and the sealing plug has an axial length L3, and the length L3 satisfies the following relationship:

[0011]

[0012] Right now

[0013]

[0014] There is a length L7 between endpoint A and endpoint B, and the length L7 satisfies the following relationship:

[0015] L7=L3sinα (3)

[0016] The first contact surface has a length L5, the second contact surface has a length L6, and the lengths L5, L6 and L7 satisfy the following relationship:

[0017]

[0018] In order to better realize the negative Poisson's ratio effect, the area of ​​the first contact surface is smaller than the area of ​​the second contact surface, so that the load-bearing structure can expand laterally within the elastic range when stretched, and the material can shrink laterally when compressed.

[0019] The present invention also provides an underground gas storage, comprising a gas storage cavern arranged in the surrounding rock, a first pipeline connected to the gas storage cavern and the above-mentioned sealing plug, wherein the sealing plug is arranged close to the gas storage cavern on a side away from the retaining wall, and the first pipeline passes through the sealing plug.

[0020] The above-mentioned underground gas storage using a sealing plug makes full use of the tensile expansion characteristics of the load-bearing structure and the compressive expansion characteristics of the body (concrete), so that the radial expansion of the sealing plug under the action of horizontal thrust is more significant, which can make the sealing plug closer to the surrounding rock wall and significantly improve the anti-slip stability of the sealing plug.

[0021] Preferably, anchor rods are provided in the surrounding rock, the anchor rods are provided close to the retaining wall, radially extending steel bars are provided on the retaining wall, and the steel bars are connected to the anchor rods. Steel bars only need to be provided on the retaining wall, and no steel bars are required at other locations, thereby reducing the amount of steel bars used and ensuring the stability of the retaining wall connection structure.

[0022] Preferably, the steel bars are evenly distributed in plurality along the circumference of the sealing plug.

[0023] Preferably, backfill concrete is provided between the sealing plug and the gas storage cavern.

[0024] Preferably, a lane is provided on one side of the retaining wall of the sealing plug, the lane is provided with a second pipeline, and the first pipeline extends into the lane and is connected with the second pipeline.

[0025] The present invention also provides a method for constructing the above-mentioned underground gas storage, comprising: designing the size of the sealing plug according to the surrounding rock environment, and prefabricating the load-bearing structure; successively excavating the tunnel, the gas storage cavern and the installation space of the sealing plug in the surrounding rock; installing a first pipeline to connect the gas storage cavern, and backfilling concrete on one side of the gas storage cavern; installing the load-bearing structure; pre-burying backfill grouting pipes on the first contact surface and the second contact surface where the surrounding rock contacts the load-bearing structure; casting the main body and filling the retaining wall through the backfill grouting pipes; and completing the construction.

[0026] Compared with the related art, the present invention has the following beneficial effects:

[0027] 1. The present invention designs the sealing plug to have a main body with a truncated cone and a load-bearing structure with a first contact surface and a second contact surface, and the first contact surface and the second contact surface have an angle in the axial direction of the main body, thereby forming a variable cross-section structure of the sealing plug, so that the sealing plug not only meets the high pressure, cyclic load and cyclic impact requirements under the operating conditions of the gas storage reservoir, reduces the risk of structural instability, but also has a simple structure, convenient construction and higher reliability;

[0028] Second, the present invention designs the load-bearing structure into two layers, wherein the first layer is connected to the main body of the truncated cone, and the first contact surface and the second contact surface designed with an angle fit the surrounding rock, so that the maximum shear stress area borne by the sealing plug is concentrated as much as possible inside the load-bearing structure, which can significantly improve the shear resistance of the sealing plug;

[0029] 3. The present invention optimizes the structure of the sealing plug, so that its radial expansion characteristics are more significant under the action of horizontal thrust, so that the sealing plug is more closely attached to the surrounding rock wall, and the anti-slip stability of the sealing plug is significantly improved;

[0030] Fourth, the present invention optimizes the structure of the sealing plug, so that it has a better energy absorption function, can effectively improve its impact resistance, and at the same time reduce the shear damage of the sealing plug to the surrounding rock, thereby improving the structural reliability and service life of the sealing plug;

[0031] 5. The sealing plug is mainly formed by plain concrete, which reduces the amount of steel used and is easy to install, which can reduce the construction period of the sealing plug; it can be suitable for the design and construction of sealing plugs for high-pressure caverns such as hydraulic tunnels, oil caverns, and gas storages. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure of the underground gas storage provided by the present invention;

[0033] Figure 2 For along Figure 1 A cross-sectional schematic diagram of the FF in FIG.

[0034] Figure 3 For along Figure 1 A cross-sectional schematic diagram of GG in FIG.

[0035] Figure 4 A schematic diagram of the structure of the sealing plug provided by the present invention;

[0036] Figure 5 for Figure 4 The enlarged force analysis diagram at E in the figure;

[0037] Figure 6 A schematic diagram of the force analysis of the sealing plug provided by the present invention. DETAILED DESCRIPTION

[0038] The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear in the following, they only indicate that the upper, lower, left and right directions are consistent with the drawings themselves, and do not limit the structure.

[0039] like Figure 1 As shown, an underground gas storage provided in this embodiment includes a gas storage cavern 1 disposed in a surrounding rock 11, a first pipeline 7 connected to the gas storage cavern 1, a sealing plug 12 disposed beside the gas storage cavern 1, a tunnel 6 for excavating a space for installing the gas storage cavern 1 and the sealing plug 12, and a second pipeline 8 connected to the first pipeline 7. The first pipeline 7 is a maintenance pipeline, one end of which is connected to the gas storage cavern 1, and the other end of which passes through the sealing plug 12 and extends into the tunnel 6 (as shown in FIG. Figure 2 The second pipeline 8 is a gas charging and discharging pipeline.

[0040] like Figure 4 As shown, the sealing plug 12 includes a body 2, a bearing structure 3 mounted on the outside of the body 2, and a retaining wall 4 arranged on one end of the body 2 and the bearing structure 3. The body 2 is a truncated cone made of concrete, which mainly bears the pressure of the gas storage chamber 1, and is subjected to very little tensile stress, and transmits the pressure to the bearing structure 3 and the retaining wall 4, making full use of the characteristics of the body 2 concrete having strong compressive resistance and weak tensile resistance.

[0041] The load-bearing structure 3 is made of a negative Poisson's ratio material, and is provided with a first layer 31 and a second layer 32 from the inside to the outside. The first layer 31 is attached to the outer surface of the body 2, and the second layer 32 is provided with a first contact surface 321 and a second contact surface 322 on the outer periphery, and the first contact surface 321 and the second contact surface 322 have an angle in the axial direction of the body 2. And the area of ​​the first contact surface 321 is smaller than the area of ​​the second contact surface 322.

[0042] The retaining wall 4 includes a skeleton and backfill concrete, and its main function is to control the coordinated deformation of the main body 2 and the load-bearing structure 3 in the horizontal direction, prevent the main body 2 and the load-bearing structure 3 from having a large slip, provide horizontal deformation constraints for the main body 2, and also provide a certain horizontal reverse thrust.

[0043] like Figure 6 As shown in the figure, under the action of pressure load p, the body 2 transmits the normal pressure σ to the load-bearing structure 3. Due to the negative Poisson's ratio effect of the load-bearing structure 3, under the action of the normal pressure σ, the load-bearing structure 3 mainly contracts and deforms along the direction approximately along the x-axis. According to the elastic-plastic mechanics analysis, the surface where the maximum shear stress is located is at an angle of 45° to the main plane. Under the action of the main tensile stress, the load-bearing structure 3 will expand and deform along the direction approximately along the y-axis. Therefore, the main deformation direction of the load-bearing structure 3 is as follows Figure 6 It can be seen that under the action of the pressure load p, the load-bearing structure 3 will deform in the direction of being close to the rock wall, which further strengthens the contact between the load-bearing structure 3 and the rock wall of the surrounding rock 11 and increases the reverse thrust provided by the surrounding rock 11.

[0044] like Figure 4 , Figure 5As shown, the first layer 31 has endpoints A and B at both ends, and the body 2 has endpoints C and D at both ends. The vertical distance between endpoints A and C is d1, and the vertical distance between endpoints B and D is d2. The endpoint A has a diameter L1, the retaining wall 4 has a diameter L2, L1≥L2, and the sealing plug has an axial length L3, and the length L3 satisfies the following relationship:

[0045]

[0046] Right now

[0047]

[0048] To ensure that concrete and load-bearing structures can effectively bear and transfer forces, the following conditions must be met:

[0049]

[0050] and

[0051] d2≥d1 (4)

[0052] There is a length L7 between the end point A and the end point B, that is, L7 is the maximum shear stress surface length of the load-bearing structure 3, which satisfies:

[0053] L7=L3sinα (5)

[0054] The first contact surface 321 has a length L5, and the second contact surface 322 has a length L6. The lengths L5, L6, and L7 satisfy the following relationship:

[0055]

[0056] according to Figure 5 From the stress and deformation analysis of the microelement on the maximum shear stress surface, it can be seen that the maximum tensile stress direction and the main deformation direction of the microelement are both at a 45° angle to the maximum shear stress surface, and the main deformation direction of the microelement is In order to enable the L6 contact surface to bear more load, it should be ensured that the main deformation direction of the load-bearing structure is close to perpendicular to the L6 contact surface. Therefore, it is necessary to meet the following conditions:

[0057] α+45°-θ=90°

[0058] Right now

[0059] α-θ=45°

[0060] Considering the influence of the excavation range of the sealing plug size in different projects, the main deformation direction of the load-bearing structure 3 and the contact surface of L6 should be kept at a large angle as much as possible, that is, to meet the following requirements:

[0061] α+45°-θ>60°

[0062] Right now

[0063] α-θ>15°

[0064] like Figure 3 As shown, an anchor rod 5 is provided in the surrounding rock 11, and the anchor rod 5 is arranged close to the retaining wall 4. The retaining wall 4 is provided with radially extending steel bars 10, and the steel bars 10 are connected to the anchor rod 5. A plurality of the steel bars 10 are evenly distributed along the circumference of the sealing plug.

[0065] like Figure 1 As shown, backfill concrete 9 is provided between the sealing plug 12 and the gas storage cavern 1 .

[0066] The present invention also provides a method for constructing the lower gas storage reservoir, comprising the following steps:

[0067] S1, design the sealing plug size according to the surrounding rock environment;

[0068] S2, successively excavating the tunnel 6, the gas storage cavern 1 and the installation space of the sealing plug 12 in the surrounding rock 11;

[0069] S3, installing the first pipe 7 to connect the gas storage cavern 1, and backfilling concrete on one side of the gas storage cavern 1; and then roughening the surface of the backfilled concrete 9;

[0070] S4, installing the load-bearing structure 3, and pre-burying the backfill grouting pipe on the first contact surface 321 and the second contact surface 322 where the surrounding rock contacts the load-bearing structure 3;

[0071] S5, pre-buried contact grouting pipe outside the first pipeline 7;

[0072] S6, tying the steel bars 10 on the retaining wall 4 to the anchor rods 5;

[0073] S7, casting the forming body 2 and the filling retaining wall 4 through the backfill grouting pipe, and successively performing backfill grouting and contact grouting; and completing the construction.

[0074] Example

[0075] The main body 1 is designed as a truncated cone wedge, with a circular section diameter of L1 = 6m on the compression side and a circular section diameter of L2 = 6m on the retaining wall 4 side. Considering θ = 70° and α = 85°, the sealing plug length L3 is 11.40m, and d1 = d2 = 1.5m is set. The internal pressure of the gas storage cavern 1 is transmitted to the sealing plug 12 through backfill concrete with an approximately horizontal pressure load p, which can make the maximum shear stress of the sealing plug 12 mainly concentrated in the load-bearing structure 3, making full use of the excellent shear resistance of the negative Poisson's ratio structure.

[0076] The present invention utilizes the difference between the negative Poisson's ratio structure and the Poisson's ratio structure (conventional concrete) in deformation and force to design the structural form of the sealing plug, and gives full play to the special performance of the negative Poisson's ratio structure in force, energy absorption and deformation, and increases the friction and positive pressure between the sealing plug and the surrounding rock to bear the pressure load transmitted by the gas storage cavern. The present invention aims to design a sealing plug with strong bearing capacity, good impact resistance, convenient construction and long service life by combining the negative Poisson's ratio structure with concrete.

[0077] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A sealing plug, characterized in that: The invention comprises a body (2), a load-bearing structure (3) made of a negative Poisson's ratio material and mounted on the outside of the body (2), and a retaining wall (4) arranged on one axial end side of the body (2) and the load-bearing structure (3); the body (2) is a truncated cone; the load-bearing structure (3) is provided with a first layer (31) and a second layer (32) from the inside to the outside; the first layer (31) is attached to the outer surface of the body (2); the outer surface of the second layer (32) is provided with a first contact surface (321) and a second contact surface (322); the first contact surface (321) and the second contact surface (322) have an angle in the axial direction of the body (2).

2. The sealing plug according to claim 1, characterized in that: The first layer (31) is provided with an endpoint A and an endpoint B at both ends of the axial direction, and the body (2) is provided with an endpoint C and an endpoint D at both ends, the vertical distance between endpoint A and endpoint C is d1, the vertical distance between endpoint B and endpoint D is d2, and d2≥d1.

3. The sealing plug according to claim 2, characterized in that: The end point A is formed with a diameter L1, the retaining wall (4) has a diameter L2, L1≥L2, and the sealing plug has an axial length L3, and the length L3 satisfies the following relationship: Right now There is a length L7 between endpoint A and endpoint B, and the length L7 satisfies the following relationship: L7=L3sinα (3) The first contact surface (321) has a length L5, and the second contact surface (322) has a length L6. The lengths L5, L6, and L7 satisfy the following relationship:

4. The sealing plug according to claim 1, characterized in that: The area of ​​the first contact surface (321) is smaller than the area of ​​the second contact surface (322).

5. An underground gas storage, comprising a gas storage cavern (1) disposed in a surrounding rock (11) and a first pipeline (7) communicating with the gas storage cavern (1), characterized in that: It also comprises a sealing plug as claimed in any one of claims 1 to 4, wherein the sealing plug is arranged close to the gas storage cavern (1) on a side away from the retaining wall (4), and the first pipe (7) passes through the sealing plug.

6. The underground gas storage according to claim 5, characterized in that: An anchor rod (5) is provided in the surrounding rock (11), and the anchor rod (5) is arranged close to the retaining wall (4). The retaining wall (4) is provided with radially extending steel bars (10), and the steel bars (10) are connected to the anchor rod (5).

7. The underground gas storage according to claim 6, characterized in that: A plurality of the steel bars (10) are evenly distributed along the circumference of the sealing plug.

8. The underground gas storage according to claim 5, characterized in that: Backfill concrete (9) is provided between the sealing plug and the gas storage cavern (1).

9. The underground gas storage according to claim 5, characterized in that: A tunnel (6) is provided on one side of the retaining wall (4) of the sealing plug, the tunnel (6) is provided with a second pipeline (8), and the first pipeline (7) extends into the tunnel (6) and is connected to the second pipeline (8).

10. A method for constructing an underground gas storage according to any one of claims 5 to 9, characterized in that: include: According to the surrounding rock environment, the size of the sealing plug is designed, and the load-bearing structure (3) is prefabricated and processed; the tunnel (6), the gas storage cavern (1) and the installation space of the sealing plug are excavated in the surrounding rock (11) in sequence; the first pipeline (7) is installed to connect the gas storage cavern (1), and concrete is backfilled on one side of the gas storage cavern (1); the load-bearing structure (3) is installed; the backfill grouting pipe is pre-buried on the first contact surface (321) and the second contact surface (322) where the surrounding rock and the load-bearing structure (3) contact; the main body (2) and the filling retaining wall (4) are cast through the backfill grouting pipe; and the construction is completed.

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