Underground high-pressure gas storage unfavorable geological section treatment structure and design method thereof

Abstract

The invention provides an unfavorable geological section treatment structure of an underground high-pressure gas storage and a design method of the unfavorable geological section treatment structure. The treatment structure comprises replacement concrete arranged between a weak structural layer and backfill concrete. The section of the replacement concrete in the radial direction of the gas storage is an isosceles trapezoid, the upper bottom edge of the isosceles trapezoid is connected with the weak structure layer, the lower bottom edge of the isosceles trapezoid is connected with the backfill concrete, the two waist edges of the isosceles trapezoid are connected with the surrounding rocks on the two sides of the replacement concrete respectively, and the length L3 of the upper bottom edge is smaller than the length L1 of the lower bottom edge. The treatment structure can prevent the safety problem of the gas storage caused by the characteristics of low strength, easy deformation and the like of the weak structural layer.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed air energy storage, and in particular to a structure for processing poor geological sections of underground high-pressure gas storage and a design 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] Due to the uncertainty of geological conditions and the limitations of many factors such as the scope of the project site, the level of geological survey, and the scale of the project, it is usually difficult for gas storage caverns to avoid crossing or intersecting weak structural layers such as weak interlayers and faults. Since the weak structural layers have low strength and are easy to deform, they pose a great threat to the stability of the cavern surrounding rock and the safety of the sealing structure. At the same time, the exposed thickness of the weak structural layers in different cave sections is not the same, and the degree of influence of weak structural layers of different thicknesses on the stability of the cavern structure is also different. Therefore, reasonable structural treatment and design for weak structural layers of different thicknesses is crucial to ensure the safety and stability of the gas storage during the operation period.

[0004] In summary, there is an urgent need for an underground high-pressure gas storage reservoir with poor geological sections and a design method thereof to solve the problems existing in the prior art. Summary of the invention

[0005] The purpose of the present invention is to provide a structure for treating bad geological sections of underground high-pressure gas storage, aiming to solve the problem that the weak structural layer, due to its low strength and easy deformation, poses a great threat to the stability of the surrounding rock of the cavern and the safety of the sealing structure. The specific technical scheme is as follows:

[0006] A treatment structure for poor geological sections of an underground high-pressure gas storage reservoir, the gas storage reservoir comprising a sealing steel plate, backfill concrete and surrounding rock, wherein the backfill concrete is arranged between the sealing steel plate and the surrounding rock, and the treatment structure comprises replacement concrete arranged between a weak structural layer and the backfill concrete; the cross-section of the replacement concrete in the radial direction of the gas storage reservoir is an isosceles trapezoid, the upper base of the isosceles trapezoid is connected to the weak structural layer, the lower base is connected to the backfill concrete, and the two waists are respectively connected to the surrounding rock on both sides of the replacement concrete, and the length L3 of the upper base is less than the length L1 of the lower base.

[0007] Preferably in the above technical solution, the length L3 of the upper bottom edge is equal to the maximum thickness of the weak structural layer, and the two end points of the upper bottom edge are respectively connected to the surrounding rocks on both sides of the weak structural layer.

[0008] Preferably in the above technical solution, the distance L2 between the upper base and the lower base and the length L3 of the upper base satisfy: L2=N·L3, wherein N is 1.5-2.0.

[0009] Preferably in the above technical solution, the angle θ between the waist of the isosceles trapezoid and the horizontal plane is 30°-60°.

[0010] The present invention also provides a design method for the treatment structure of the bad geological section of the underground high-pressure gas storage reservoir, the design method includes verifying whether the structural stability safety factor of the current treatment structure is qualified, and the specific steps are as follows:

[0011] S1. Determine the structural dimensions of the gas storage and the proposed dimensions of the processing structure;

[0012] S2. Calculate the thrust force F on the replacement concrete d The thrust F generated by the internal pressure of the gas storage tank on the replacement concrete u ;

[0013] S3. According to F d and F u Calculate the structural stability safety factor K of the processed structure s ;

[0014] S4. The structural stability safety factor K s Compared with the specified structural stability safety factor K′ s For comparison, if K s ≥K′ s The verification is then ended, otherwise the proposed size of the processing structure and / or the structural size of the gas storage reservoir is adjusted and the process returns to step S1.

[0015] In the above technical solution, the thrust force F exerted on the replacement concrete is calculated according to formula (9): d :

[0016] F d =F s cosθ+F n sinθ (9),

[0017] According to formula (10), the thrust F generated by the internal pressure of the gas storage tank on the replacement concrete is calculated as u :

[0018]

[0019] Among them, F n is the normal pressure on the replacement surface of the replacement concrete, F s is the shear force on the displacement surface of the replacement concrete, θ is the angle between the displacement surface and the horizontal, p is the internal pressure of the gas storage, p2 is the internal pressure borne by the surrounding rock, σR is the resistance limit of the sealing steel plate, t is the thickness of the sealing steel plate, r is the radius of the sealing steel plate, and L1 is the length of the lower bottom side of the replacement concrete section in the radial direction of the gas storage reservoir.

[0020] In the above technical solution, the positive pressure F on the replacement surface of the replacement concrete is calculated according to formula (6): n :

[0021]

[0022] According to formula (7), the shear force F on the replacement surface of the replacement concrete is calculated as s :

[0023]

[0024] Where, dl is the differential unit; L2 is the distance between the upper and lower bases of the replacement concrete; σ n represents the normal stress acting on the displacement surface; τ n represents the shear stress acting on the displacement surface; θ is the angle between the displacement surface and the horizontal direction; f R is the friction coefficient between replacement concrete and surrounding rock.

[0025] In the above technical solution, the normal stress σ acting on the displacement surface is calculated according to formula (4): n :

[0026]

[0027] The shear stress τ acting on the displacement surface is calculated according to formula (5): n :

[0028] τ n =σ n f R +C R (5)

[0029] Among them, σ x is the horizontal geostress of the gas storage reservoir; y is the vertical geostress of the gas storage reservoir; θ is the angle between the displacement surface and the horizontal direction; f R is the friction coefficient between replacement concrete and surrounding rock; C R is the cohesion between replacement concrete and surrounding rock; π is the pi.

[0030] The preferred technical solution is to calculate the structural stability safety factor K of the current processing structure according to formula (11): s :

[0031]

[0032] The present invention also provides another design method for the treatment structure of the bad geological section of the underground high-pressure gas storage reservoir, the design method includes determining the most economical thickness of the sealing steel plate, and the specific steps are as follows:

[0033] A1. Determine the hole diameter and safety level of the gas storage reservoir, and determine the proposed size of the treatment structure;

[0034] A2. Determine the structural stability safety factor K′ specified for replacement concrete according to the hole diameter and safety level of the gas storage reservoir s At the same time, calculate the thrust force F on the replacement concrete d ;

[0035] A3. Calculate the most economical thickness t′ of the sealing steel plate;

[0036]

[0037] Where p is the internal pressure of the gas storage; σ R is the resistance limit of the sealing steel plate; r is the radius of the sealing steel plate; L1 is the length of the lower bottom side of the replacement concrete in the radial direction of the gas storage reservoir.

[0038] The application of the technical solution of the present invention has the following beneficial effects:

[0039] The cross-section of the replacement concrete in the radial direction of the gas storage reservoir is an isosceles trapezoid, and the lower base is a long side with a larger contact area with the backfill concrete, thereby reducing the pressure on the replacement concrete and preventing the replacement concrete from being damaged; at the same time, through the two waist edges connected to the surrounding rock, the internal pressure on the replacement concrete can be evenly distributed to the surrounding rocks on both sides, reducing the stress on the weak structural layer, and preventing the weak structural layer from causing safety problems to the gas storage reservoir due to its low strength, easy deformation and other characteristics.

[0040] The design method of the present invention can verify whether the structural stability safety factor of the current processing structure is qualified, discover design deficiencies in a timely manner, and help designers adjust relevant structural dimensions in a timely manner; at the same time, by performing structural stability safety factor verification, it can help designers understand the key factors affecting the structural stability safety factor and provide direction for adjusting the structural stability safety factor.

[0041] The design method of the present invention can help designers quickly determine the most economical thickness of the sealing steel plate, while ensuring the structural stability of the gas storage reservoir in the weak structural layer section, and at the same time, reduce the thickness of the sealing steel plate as much as possible to save engineering investment.

[0042] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0044] Figure 1 is a schematic cross-sectional view of a gas storage reservoir after adopting the processing structure of the present invention;

[0045] Figure 2 yes Figure 1 Schematic diagram of the local structure at A in the middle;

[0046] Figure 3 It is a flow chart for verifying the structural stability safety factor of the current processing structure;

[0047] Figure 4 It is a flow chart for determining the most economical thickness of the sealing steel plate;

[0048] Figure 5 It is a construction flow chart for processing structures;

[0049] Among them, 1-weak structural layer; 2-surrounding rock; 3-replacement concrete; 4-replacement surface; 5-sealing steel plate; 6-backfill concrete; 7-gas storage. DETAILED DESCRIPTION

[0050] In order to facilitate the understanding of the present invention, the present invention will be described more fully below, and preferred embodiments of the present invention are provided. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0052] Embodiment 1:

[0053] The existing underground high-pressure gas storage reservoir 7 is generally a joint load-bearing structure composed of a sealing steel plate 5, backfill concrete 6, and surrounding rock 2; the backfill concrete 6 is arranged between the sealing steel plate 5 and the surrounding rock 2, and the function of the sealing steel plate 5 is to prevent leakage of high-pressure gas and bear part of the internal pressure; the backfill concrete 6 is a force transmission structure, which is responsible for evenly transmitting the pressure to the surrounding rock 2, and the internal pressure it bears can be ignored as a safety reserve; the surrounding rock 2 bears most of the pressure load inside the gas storage reservoir 7.

[0054] Due to the uncertainty of geological conditions and the limitations of many factors such as the scope of the project site, the level of geological survey, and the scale of the project, the gas storage reservoir 7 is usually difficult to avoid crossing or intersecting the weak structural layer 1 (i.e., the unfavorable geological section, such as weak interlayers, faults, etc.). The weak structural layer 1 has problems such as low strength and easy deformation, which poses a great threat to the stability of the surrounding rock and the safety of the sealing structure of the gas storage reservoir 7. In this regard, this embodiment provides a structure for processing unfavorable geological sections of underground high-pressure gas storage reservoirs, such as Figure 1-Figure 2 As shown, the treatment structure includes replacement concrete 3 arranged between the weak structural layer 1 and the backfill concrete 6; the cross-section of the replacement concrete 3 in the radial direction of the gas storage reservoir 7 is an isosceles trapezoid, the upper base of the isosceles trapezoid is connected to the weak structural layer 1, the lower base is connected to the backfill concrete 6, and the two waists are respectively connected to the surrounding rocks 2 on both sides of the replacement concrete 3, and the length L3 of the upper base is less than the length L1 of the lower base.

[0055] In this embodiment, the cross section of the replacement concrete in the radial direction of the gas storage reservoir is an isosceles trapezoid, and the lower bottom side is the long side and has a large contact area with the backfill concrete 6, which reduces the pressure on the replacement concrete and prevents the replacement concrete from being damaged; at the same time, through the two waist sides connected to the surrounding rock, the internal pressure on the replacement concrete can be evenly distributed to the surrounding rock on both sides, reducing the stress on the weak structural layer, and preventing the weak structural layer from causing safety problems to the gas storage reservoir due to its low strength and easy deformation. Among them, when the replacement concrete 3 is constructed, a groove is first excavated at the position of the weak structural layer 1 and the groove excavation section is measured. When the design requirements are met, the base surface is cleaned; after the groove excavation is completed, the replacement concrete 3 is poured at the groove excavation position.

[0056] Furthermore, the length L3 of the upper bottom edge is equal to the maximum thickness of the weak structural layer 1, such as Figure 2 As shown, the two end points of the upper base are respectively connected to the surrounding rocks 2 on both sides of the weak structural layer 1; the height L2 of the isosceles trapezoid (i.e., the distance between the upper base and the lower base) and the length L3 of the upper base satisfy: L2=N·L3, where N is 1.5-2.0, to ensure the structural strength of the replacement concrete 3.

[0057] The waist of the isosceles trapezoid represents the replacement surface 4 where the replacement concrete 3 and the surrounding rock 2 meet. The angle between the waist of the isosceles trapezoid and the horizontal plane is θ. Although increasing the angle θ can increase the positive pressure F on the replacement surface 4 to a certain extent, n and shear force F s However, considering the construction difficulty of on-site groove excavation and replacement concrete pouring, as well as the structural strength and stress characteristics of the replacement concrete itself, the angle θ between the waist side of the isosceles trapezoid and the horizontal plane is set to 30°-60° in this embodiment.

[0058] Since the cross section of the replacement concrete 3 in the radial direction of the gas storage reservoir 7 is an isosceles trapezoid, the relationship between L1, L2, and L3 satisfies:

[0059] L1=2L2tanθ+L3 (1),

[0060] Preferably, in order to ensure that the structural strength of the replacement concrete 3 itself meets the force requirements, the strength grade of the replacement concrete in this embodiment is not less than C30.

[0061] In order to ensure the safety of the processing structure in this embodiment and the economy of the gas storage design, this embodiment also provides a design method for the above-mentioned processing structure, which provides detailed processing steps for verifying whether the structural stability safety factor of the current processing structure is qualified and for guiding the rapid determination of the most economical thickness of the sealing steel plate.

[0062] See also Figure 3 , the steps to verify whether the structural stability safety factor of the current processing structure is qualified are as follows:

[0063] S1. Determine the structural dimensions of the gas storage and the proposed dimensions of the processing structure;

[0064] Specifically, the proposed dimensions of the treatment structure include the proposed structural dimensions of the replacement concrete. The proposed dimensions of the treatment structure are determined according to the dimensions of the weak structural layer. Since the cross-section of the replacement concrete in the treatment structure in the radial direction of the gas storage reservoir is an isosceles trapezoid, the structural dimensions of the replacement concrete should meet the requirements of formula (1).

[0065] S2. Calculate the thrust force F on the replacement concrete d The thrust F generated by the internal pressure of the gas storage tank on the replacement concrete u ;

[0066] See also Figure 2 , the internal pressure sharing of the gas storage meets the formula (2):

[0067] p=p1+p2 (2), where the internal pressure p1 borne by the sealing steel plate can be expressed as:

[0068]

[0069] Where: p is the internal pressure of the gas storage reservoir; p1 is the internal pressure borne by the sealing steel plate (this part of the internal pressure is offset by the deformation of the sealing steel plate); p2 is the internal pressure borne by the surrounding rock; σ R is the resistance limit of the sealing steel plate, in MPa; t is the thickness of the sealing steel plate, in m; r is the radius of the sealing steel plate, in m.

[0070] The normal stress and shear stress on the displacement surface under the limit state are:

[0071]

[0072] τ n =σ n f R +C R (5)

[0073] Among them, σ x is the horizontal geostress of the gas storage reservoir, in MPa; σ y is the vertical geostress of the gas storage reservoir, in MPa; θ is the angle between the displacement surface and the horizontal direction, in degrees; f R is the friction coefficient between replacement concrete and surrounding rock; C R is the cohesion between replacement concrete and surrounding rock, in MPa; σ n represents the normal stress acting on the displacement surface; τ n represents the shear stress acting on the displacement surface; π is the circumference of a circle.

[0074] Get the positive pressure F on the displacement surface n and shear force F s for:

[0075]

[0076] Among them, dl is the differential unit; L2 is the distance between the upper base and the lower base of the replacement concrete (i.e., the height of the isosceles trapezoid), and the unit is m.

[0077] Substituting formula (5) into formula (7) yields:

[0078]

[0079] Calculate the thrust force F on the replacement concrete d for:

[0080] F d =F s cosθ+F n sinθ (9),

[0081] The thrust F generated by the internal pressure of the gas storage (the internal pressure here is the internal pressure p2 borne by the surrounding rock) on the replacement concrete u for:

[0082]

[0083] Among them, L1 is the length of the lower base of the replacement concrete in the radial section of the gas storage reservoir.

[0084] S3. Calculate the structural stability safety factor K of the processing structure s ;

[0085] The thrust force F on the replacement concrete is obtained. d The thrust F generated by the internal pressure of the gas storage tank on the replacement concrete u After that, the structural stability safety factor K of the current processing structure can be calculated according to formula (11): s :

[0086]

[0087] S4. The structural stability safety factor K s Compared with the specified structural stability safety factor K′ s For comparison, if K s ≥K′ s The verification is then ended, otherwise the proposed size of the processing structure and / or the structural size of the gas storage reservoir is adjusted and the process returns to step S1.

[0088] Specifically, according to the safety level and hole diameter D of the gas storage, the structural stability safety factor K′ specified under the current structural size of the gas storage is obtained by looking up the table s ; This embodiment provides the structural stability safety factor K′ under different safety levels of gas storage and different hole diameter D specifications s The value table of is shown in Table 1:

[0089] Table 1: Stability safety factor K′ of replacement concrete structure s Value table

[0090]

[0091] When K s ≥K′ s This indicates that the structural stability safety factor of the treatment structure under the current proposed size is qualified. s <K′ s This indicates that the structural stability safety factor of the processing structure under the current proposed size is unqualified, and it is necessary to adjust the proposed size of the processing structure and / or the structural size of the gas storage reservoir (the structural size of the gas storage reservoir here refers to the thickness of the sealing steel plate. When the structural size of the gas storage reservoir is not determined, the structural stability safety factor can be adjusted by adjusting the structural size of the gas storage reservoir) to ensure the safety of the gas storage reservoir. Steps S1-S4 can be used to verify whether the current structural size of the gas storage reservoir and the current proposed structural size of the processing structure meet the safety requirements, helping designers to adjust the relevant structural sizes in a timely manner.

[0092] For further information, see Figure 4 The specific steps to guide the quick determination of the most economical thickness of the sealing steel plate are as follows:

[0093] A1. Determine the hole diameter and safety level of the gas storage reservoir, and determine the proposed size of the treatment structure;

[0094] Specifically, the hole diameter and safety level of the gas storage reservoir are confirmed according to the design requirements of the gas storage reservoir, and the proposed size of the processing structure is determined to be the same as step S1, so it will not be described in detail.

[0095] A2. Determine the structural stability safety factor K′ specified for replacement concrete according to the hole diameter and safety level of the gas storage reservoir s At the same time, calculate the thrust force F on the replacement concrete d ;

[0096] Specifically, according to the hole diameter and safety level of the gas storage, the structural stability safety factor K′ specified for replacement concrete is obtained by looking up the table (i.e., looking up Table 1): s Then, according to formula (9), the thrust force F exerted on the replacement concrete is calculated. d .

[0097] A3. Calculate the most economical thickness t′ of the sealing steel plate;

[0098]

[0099] Where p is the internal pressure of the gas storage; σ R is the resistance limit of the sealing steel plate; r is the radius of the sealing steel plate; L1 is the length of the lower bottom side of the replacement concrete in the radial direction of the gas storage reservoir.

[0100] According to steps A1-A3, after confirming the proposed size of the processing structure, the most economical thickness of the sealing steel plate in the gas storage reservoir can be quickly confirmed, guiding the selection of the thickness of the sealing steel plate, thereby saving engineering investment.

[0101] See also Figure 5 The brief construction steps of the treatment structure of the bad geological section of the underground high-pressure gas storage in this embodiment are as follows:

[0102] B1. Design the thickness of the sealing steel plate and the structural dimensions of the replacement concrete according to the weak structural layer, and determine the final design after verification;

[0103] B2. Carve grooves and excavate the weak structural layer according to the design plan, measure the excavation section, and clean the base surface after it meets the design requirements;

[0104] B3. Embed sensors, grouting pipes and other embedded parts;

[0105] B4. Set up formwork and pour replacement concrete;

[0106] B5. After the strength of the replacement concrete meets the requirements, the formwork is removed and backfilling and grouting are carried out;

[0107] B6. After passing the quality inspection, pour the replacement soil of the next section.

[0108] Embodiment 2:

[0109] The net cross-sectional diameter of a compressed air energy storage cavern is 8m, the designed maximum operating pressure is 8MPa, the safety level of the gas storage is level 1, the sealing steel plate is made of Q490R steel, and the designed thickness of the steel plate is 30mm; the measured ground stress σ x =9MPa,σ y =7MPa; a weak interlayer with a maximum thickness of 0.8m is exposed at the waist of some sections of the cave.

[0110] The design adopts C30 replacement concrete, and the structural dimensions of the replacement concrete are L1=4.0m; L2=1.6m; L3=0.8m; θ=45°; f R The value is 0.8, C R The value is 0.8MPa. The structural stability safety factor of the replacement concrete is calculated to be K s =1.12, which is greater than the specified 1.10. The replacement concrete structure in this embodiment meets the requirement.

[0111] Embodiment 3:

[0112] The net cross-sectional diameter of a compressed air energy storage cavern is 8m, the designed maximum operating pressure is 8MPa, the safety level of the gas storage is level 1, the sealing steel plate is made of Q490R steel, and the measured ground stress σ x =9MPa,σ y =7MPa, and a weak interlayer with a maximum thickness of 1.0m is exposed at the waist of some sections of the cave.

[0113] The design adopts C30 replacement concrete, and the structural dimensions of the replacement concrete are L1=5.0m; L2=2m; L3=1.0m; θ=45°; f R The value is 0.8, C R The value is 0.8MPa. Under the premise of satisfying the structural stability safety factor of not less than 1.10, the most economical sealing steel plate thickness t′=27mm is calculated.

[0114] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A structure for treating a bad geological section of an underground high-pressure gas storage reservoir, wherein the gas storage reservoir (7) comprises a sealing steel plate (5), backfill concrete (6) and surrounding rock (2), wherein the backfill concrete (6) is arranged between the sealing steel plate (5) and the surrounding rock (2), and characterized in that: The treatment structure comprises replacement concrete (3) arranged between the weak structural layer (1) and the backfill concrete (6); the cross section of the replacement concrete (3) in the radial direction of the gas storage reservoir (7) is an isosceles trapezoid, the upper base of the isosceles trapezoid is connected to the weak structural layer (1), the lower base is connected to the backfill concrete (6), and the two waists are respectively connected to the surrounding rocks (2) on both sides of the replacement concrete (3), and the length L3 of the upper base is less than the length L1 of the lower base.

2. The structure for treating bad geological sections of underground high-pressure gas storage according to claim 1 is characterized in that: The length L3 of the upper bottom edge is equal to the maximum thickness of the weak structural layer (1), and the two end points of the upper bottom edge are respectively connected to the surrounding rocks (2) on both sides of the weak structural layer (1).

3. The structure for treating bad geological sections of underground high-pressure gas storage according to claim 1 is characterized in that: The distance L2 between the upper base and the lower base and the length L3 of the upper base satisfy the following condition: L2=N·L3, wherein N is 1.5-2.

0.

4. The structure for processing bad geological sections of underground high-pressure gas storage according to claim 1 is characterized in that: The angle θ between the waist of the isosceles trapezoid and the horizontal plane is 30°-60°.

5. A method for designing a structure for treating a bad geological section of an underground high-pressure gas storage according to any one of claims 1 to 4, characterized in that: The design method includes verifying whether the structural stability safety factor of the current treatment structure is qualified, and the specific steps are as follows: S1. Determine the structural dimensions of the gas storage and the proposed dimensions of the processing structure; S2. Calculate the thrust force F on the replacement concrete d The thrust F generated by the internal pressure of the gas storage tank on the replacement concrete u ; S3. According to F d and F u Calculate the structural stability safety factor K of the processed structure s ; S4. The structural stability safety factor K s Compared with the specified structural stability safety factor K′ s For comparison, if K s ≥K′ s The verification is then ended, otherwise the proposed size of the processing structure and / or the structural size of the gas storage reservoir is adjusted and the process returns to step S1.

6. The design method according to claim 5, characterized in that: According to formula (9), the thrust force F exerted on the replacement concrete is calculated: d : F d =F s cosθ+F n sinθ (9), According to formula (10), the thrust F generated by the internal pressure of the gas storage tank on the replacement concrete is calculated as u : Among them, F n is the normal pressure on the replacement surface of the replacement concrete, F s is the shear force on the displacement surface of the replacement concrete, θ is the angle between the displacement surface and the horizontal, p is the internal pressure of the gas storage, p2 is the internal pressure borne by the surrounding rock, σ R is the resistance limit of the sealing steel plate, t is the thickness of the sealing steel plate, r is the radius of the sealing steel plate, and L1 is the length of the lower bottom side of the replacement concrete section in the radial direction of the gas storage reservoir.

7. The design method according to claim 6, characterized in that: According to formula (6), the positive pressure F on the replacement surface of the replacement concrete is calculated as n : According to formula (7), the shear force F on the replacement surface of the replacement concrete is calculated as s : Where, dl is the differential unit; L2 is the distance between the upper and lower bases of the replacement concrete; σ n represents the normal stress acting on the displacement surface; τ n represents the shear stress acting on the displacement surface; θ is the angle between the displacement surface and the horizontal direction; f R is the friction coefficient between replacement concrete and surrounding rock.

8. The design method according to claim 7, characterized in that: According to formula (4), the normal stress σ acting on the displacement surface is calculated as n : The shear stress τ acting on the displacement surface is calculated according to formula (5): n : t n =s n f R +C R (5), Among them, σ x is the horizontal geostress of the gas storage reservoir; y is the vertical geostress of the gas storage reservoir; θ is the angle between the displacement surface and the horizontal direction; f R is the friction coefficient between replacement concrete and surrounding rock; C R is the cohesion between replacement concrete and surrounding rock; π is the pi.

9. The design method according to claim 5, characterized in that: According to formula (11), the structural stability safety factor K of the current treatment structure is calculated s :

10. A method for designing a structure for treating a bad geological section of an underground high-pressure gas storage according to any one of claims 1 to 4, characterized in that: The design method includes determining the most economical thickness of the sealing steel plate, and the specific steps are as follows: A1. Determine the hole diameter and safety level of the gas storage reservoir, and determine the proposed size of the treatment structure; A2. Determine the structural stability safety factor K′ specified for replacement concrete according to the hole diameter and safety level of the gas storage reservoir s At the same time, calculate the thrust force F on the replacement concrete d ; A3. Calculate the most economical thickness t' of the sealing steel plate; Where p is the internal pressure of the gas storage; σ R is the resistance limit of the sealing steel plate; r is the radius of the sealing steel plate; L1 is the length of the lower bottom side of the replacement concrete in the radial direction of the gas storage reservoir.

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