Design method for thickness of sealing steel plate of underground gas storage

Abstract

The present application relates to a kind of underground gas storage sealing steel plate thickness design method, comprising the following steps: determining the yield strain value of the steel material of selected sealing steel plate;Under the condition that there is surrounding rock crack outside sealing steel plate, the limit strain value of sealing steel plate in operating period is obtained;The size of yield strain value and limit strain value is compared, when limit strain value is less than the yield strain value of steel material, the fatigue endurance of sealing steel plate is calculated;According to fatigue endurance, the thickness of required sealing steel plate is determined.A kind of underground gas storage is also provided, and the steel plate obtained by the above underground gas storage sealing steel plate thickness design method is used.The actual thickness of sealing steel plate is determined by cross-seam condition and fatigue endurance condition in the present application, compared with the existing steel plate fire toxicity selection method, the reliability of sealing steel plate is quantitatively analyzed, and suitable steel plate thickness can be obtained quickly and accurately, and reliable solution can be provided for steel plate sealing gas storage design.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed air energy storage, and in particular to a method for designing the thickness of a sealing steel plate of an underground gas storage reservoir. Background Art

[0002] Compressed air energy storage (CAES) technology, as an emerging energy storage method, has attracted widespread attention worldwide in recent years. Its basic principle is to compress and store air during periods of low electricity demand, and then release the compressed air to drive generators during peak periods, thereby storing and releasing electricity. This technology is not only environmentally friendly and efficient, but also offers the potential for long-term energy storage, making it of great significance for improving energy efficiency and promoting the development of renewable energy. With the rapid development and widespread application of CAES technology, demand for underground gas storage, a key infrastructure in this field, is growing steadily.

[0003] How to ensure that there is no air leakage in underground gas storage caverns or to control air leakage within the allowable value is one of the key issues in compressed gas energy storage technology.

[0004] Underground gas storage caverns are a crucial component of compressed gas energy storage power plants. They typically consist of a sealing layer, backfill concrete, and surrounding rock. The sealing layer serves only as a seal and does not bear pressure. Thin steel plates or polymer materials can be used for the sealing layer. Thin steel plates offer excellent compression resilience, resistance to softening at high temperatures, and resistance to brittle cracking at low temperatures. These thin steel plates are currently a popular choice among designers when comparing underground gas storage cavern project proposals in China.

[0005] The primary function of the compressed gas energy storage cavern sealing structure (layer) is to prevent high-pressure air leakage within the cavern and ensure the chamber's tightness. Therefore, tightness is the most important performance characteristic of the compressed gas energy storage cavern sealing layer. Although the surrounding rock bears the primary load of the compressed gas energy storage liner cavern, the sealing layer also needs to transfer the high internal pressure to the surrounding rock, deforming in coordination with the surrounding rock and experiencing certain stresses and strains in the process. Therefore, the sealing layer must also meet its own mechanical strength requirements.

[0006] In summary, the sealing steel plate, serving as the sealing layer, should remain intact under various complex inflation and deflation conditions, ensuring both sealing and durability. Specifically, it should possess a certain degree of ductility and cross-fracture stiffness to ensure that the surrounding rock and structure behind the wall remain elastic even when cracked. The sealing and durability of the sealing layer are closely related to its thickness, but a definitive method for calculating sealing layer reliability is currently lacking. Selection is typically based on empirical analogy, which is inefficient and hinders the ability to determine a more appropriate sealing steel plate thickness. Summary of the Invention

[0007] The object of the present invention is to provide a method for designing the thickness of a sealing steel plate of an underground gas storage reservoir, which can at least solve some of the defects in the prior art.

[0008] To achieve the above-mentioned purpose, the embodiment of the present invention provides the following technical solution: a method for designing the thickness of a sealing steel plate of an underground gas storage, comprising the following steps:

[0009] Determine the steel yield strain value of the selected sealing steel plate;

[0010] Under the condition that surrounding rock cracks exist outside the sealing steel plate, obtaining the ultimate strain value of the sealing steel plate during the operation period;

[0011] comparing the yield strain value of the steel material with the ultimate strain value, and when the ultimate strain value is less than the yield strain value of the steel material, calculating the fatigue durability of the sealing steel plate;

[0012] The required thickness of the sealing steel plate is determined according to the fatigue durability.

[0013] Furthermore, the method for obtaining the limit strain value is specifically as follows:

[0014] First, a calculation model for the sealing steel plate cross crack is established according to the crack width, the thickness of the sealing steel plate and the pressure in the gas storage reservoir;

[0015] Then, the ultimate strain value of the sealing steel plate during the operation period is calculated based on the model.

[0016] Furthermore, the ultimate strain value includes an ultimate strain value under short-term operating conditions and an ultimate strain value under long-term operating conditions. When taking the value, the larger ultimate strain value under the two conditions is selected.

[0017] Furthermore, during long-term operation, the sealing steel plate will be corroded. The maximum corrosion amount of the sealing steel plate during the operation cycle is determined based on the environmental conditions, corrosion type, corrosion rate and corrosion environment of the gas storage reservoir. When calculating the ultimate strain value under long-term operation conditions, the thickness of the sealing steel plate after subtracting the maximum corrosion amount is used.

[0018] Furthermore, when the ultimate strain value is greater than or equal to the yield strain value of the steel, the thickness of the sealing steel plate is changed and the ultimate strain value is re-obtained until the newly obtained ultimate strain value is less than the yield strain value of the steel, and then the fatigue durability of the sealing steel plate is calculated.

[0019] Furthermore, the fatigue durability formula of the sealing steel plate is as follows:

[0020] Δδ≤γ t [Δσ]

[0021] Where Δδ is fatigue durability, γ tis the thickness or diameter correction factor of the sealing steel plate, Δσ=σ max -σ min ,σ max and σ min are the maximum stress and minimum stress in the stress cycle of the calculated part of the sealing steel plate;

[0022] If Δδ is less than or equal to γ t [Δσ], then determine the required thickness of the sealing steel plate. If Δδ is greater than or equal to γ t [Δσ], then change the thickness of the sealing steel plate and re-establish the calculation model of the sealing steel plate span.

[0023] Furthermore, the calculation formula of Δσ is as follows:

[0024]

[0025] where p max and p min are the maximum and minimum gas pressure design values ​​during the operation of the gas storage, r is the inner radius of the sealing steel plate, K0 is the unit elastic resistance coefficient of the surrounding rock, and v s is the Poisson's ratio of the sealing steel plate, E s is the elastic modulus of the steel plate, and t is the thickness of the sealing steel plate.

[0026] Furthermore, [Δσ] is the allowable stress amplitude of constant amplitude fatigue, and the calculation formula is as follows:

[0027] When n<5×10 6 hour,

[0028]

[0029] When 5×10 6 <n≤1×10 8 hour,

[0030]

[0031] When n≥1×10 8 hour,

[0032] [Δσ]=[Δσ L ] 1×108

[0033] Where n is the number of stress cycles, C and β are the parameters of the component and connection, Δσ L is the allowable stress.

[0034] Furthermore, the width of the surrounding rock crack outside the sealing steel plate is obtained in the following manner:

[0035] Determine the cross-sectional dimensions and burial depth of the caverns according to the scale, capacity, and internal pressure of the gas storage facility;

[0036] Determine the crack width of the surrounding rock cracks under the most unfavorable working conditions based on the conditions of the cavern.

[0037] An embodiment of the present invention provides another technical solution: an underground gas storage, using a steel plate obtained by the above-mentioned method for designing the thickness of a sealing steel plate for an underground gas storage.

[0038] Compared with the existing technology, the beneficial effects of the present invention are: the actual thickness of the sealing steel plate is determined comprehensively through the cross-seam conditions and fatigue durability conditions. Compared with the existing steel plate fire poison selection method, it realizes the quantitative analysis of the reliability of the sealing steel plate, can obtain the appropriate steel plate thickness quickly and accurately, and can provide a reliable solution for the design of steel plate sealed gas storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of a steel plate, surrounding rock, and a cross-fracture area in a method for designing the thickness of a sealing steel plate for an underground gas storage provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of a sealing steel plate span calculation model for a sealing steel plate thickness design method for an underground gas storage provided by an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of maximum principal strain calculation across a steel plate seam for a method for designing the thickness of a sealing steel plate for an underground gas storage provided by an embodiment of the present invention (short-term operation);

[0042] Figure 4 Schematic diagram of maximum principal strain calculation across steel plate seams for a method for designing the thickness of sealing steel plates for an underground gas storage facility provided by an embodiment of the present invention (long-term operation)

[0043] Figure 5 A schematic diagram of the expansion joint, sliding layer, and concrete coordination of a sealing steel plate for an underground gas storage provided by an embodiment of the present invention;

[0044] Figure 6 A schematic diagram of the cooperation between an expansion joint and a sealing steel plate of an underground gas storage sealing steel plate provided by an embodiment of the present invention;

[0045] Figure 7 A schematic diagram of a longitudinal expansion joint of a sealing steel plate of an underground gas storage provided by an embodiment of the present invention;

[0046] Figure 8 A schematic diagram of a longitudinal expansion joint of a sealing steel plate of an underground gas storage provided by an embodiment of the present invention;

[0047] In the accompanying drawings: 1-expansion joint; 10-first connecting section; 11-expansion section; 110-head end; 111-middle end; 112-tail end; 12-second connecting section; 13-gap; 2-slip layer; 3-concrete; 4-sealing steel plate. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] See also Figures 1 to 4 The embodiment of the present invention provides a method for designing the thickness of a sealing steel plate of an underground gas storage, which specifically includes the following steps:

[0050] S1: Determine the cross-sectional dimensions, burial depth, and layout of the cavern based on the construction scale, capacity, operating internal pressure, and other engineering characteristics of the gas storage project;

[0051] S2: Determine the crack width of the surrounding rock-structure under the most unfavorable working conditions by numerical methods, etc.

[0052] S3: Determine the yield strain of the steel plate;

[0053] S31: Determine the yield strain ε of the steel based on the stress-strain curve characteristics of the selected steel y If there is no obvious yield phenomenon in steel, the stress value when plastic deformation (permanent deformation) is 0.2% is used as the yield strength of the material. After the steel yields, although the material is not finally destroyed, it has produced relatively significant and irreversible plastic deformation.

[0054] S4: Determine the maximum corrosion amount of the steel plate during the operation cycle based on the environmental conditions, corrosion type, corrosion rate, and corrosion environment of the gas storage facility;

[0055] S41: Assuming that the operation cycle of the gas storage is m years, based on the anti-corrosion requirements of steel structures, the corrosion rate of the steel plate is determined to be v (mm / a). The corrosion amount of the steel structure is t0 = m × v, so the corrosion allowance of the steel structure is t1 = t × t0.

[0056] S5: Based on parameters such as crack width, steel plate type, and internal pressure, a calculation model for the sealing steel plate's cross-crack is established to verify whether the steel plate is in an elastic state when the surrounding rock-structure behind the wall is cracked, that is, when there is a certain crack width behind it;

[0057] S51: A calculation model is established based on the local cross-section of the steel plate across the crack. The model's transverse (x), vertical (z), and longitudinal (y) lengths are as follows: Assuming the surrounding rock-structure crack width is w and the steel plate thickness is t, the model's transverse length should be 21w, meaning 10w on each side of the crack width. Experience has shown that within this range, the size effect can be eliminated. The model's vertical length is the steel plate thickness t, and the longitudinal length can be one-third of the transverse length or the thickness t. The crack width can be determined through continuous and discontinuous calculations. The cross-crack calculation model includes initial conditions, boundary conditions, and external loads. Specifically: ① Initial conditions: Local cracks form in the surrounding rock under high internal pressure, and a cross-crack region exists between the steel plate and the surrounding rock-structure. ② External loads and boundary conditions: A local cross-crack calculation section of the steel plate is taken. During the pressurization phase, the steel plate expands outward, and the steel plate elements are subjected to tension on both sides. Simultaneously, the airside of the steel plate is subjected to internal pressure from the inflation and deflation of gases during operation. The contact side of the steel plate with the surrounding rock is vertically constrained by the surrounding rock, while the other sides are free.

[0058] S52: Determine the boundary conditions for cross-joint calculations. The contact side between the steel plate and the surrounding rock-structure is subject to vertical constraints from the surrounding rock. The free side of the steel plate and the gap between the steel plate and the surrounding rock are both free surfaces.

[0059] S53: Determine the external load for cross-slit calculations. During the pressurization phase, the steel plates expand outward, and the steel plate units are subjected to tension from the steel plates on both sides. The magnitude of the tension can be determined based on the stress characteristics of the steel plates in actual projects. At the same time, the airside of the steel plate is subjected to the internal pressure of inflation and deflation during the operation phase. The maximum operating internal pressure is applied to the airside of the steel plate.

[0060] S6: Calculate the ultimate strain of the sealing steel plate under short-term operating conditions and long-term operating conditions respectively;

[0061] S61: Based on the above, calculate the maximum principal strain of the steel plate in the short-term operation phase cross-joint verification (the steel plate is relatively intact and the thickness is the design thickness t) and the long-term operation phase cross-joint verification (the thickness t1 of the steel plate after corrosion under the action of the external environment); take the larger value as the ultimate strain ε0 of the steel plate. The calculated ε0 should be less than the yield strain ε y , otherwise adjust the thickness t until the thickness t meets the requirements;

[0062] S7: Calculate the fatigue durability of the steel plate thickness under the above conditions. Use the allowable stress amplitude method to calculate the fatigue performance of the steel plate within the specified service life. The final steel plate thickness must meet the requirements of both the seam span calculation and the durability calculation.

[0063] S71: Based on the designed stable operating life m of the gas storage facility, determine the number of cycles n for the steel plate. According to the relevant provisions on fatigue analysis in the "Standard for Design of Steel Structures" GB 50017-2017, the fatigue performance of the steel plate is calculated using the allowable stress amplitude method. The stress is calculated based on the elastic state, and the constant amplitude fatigue is calculated by keeping the stress amplitude constant within the stress cycle. The calculation is as follows:

[0064] Δδ≤γ t [Δσ]

[0065] Where Δδ is fatigue durability, γ t is the thickness or diameter correction factor of the sealing steel plate, Δσ=σ max -σ min ,σ max and σ min are the maximum stress and minimum stress in the stress cycle of the calculated part of the sealing steel plate (MPa);

[0066] S72: Δσ can be calculated numerically or estimated using the following formula:

[0067]

[0068] where p max and p min They are the maximum and minimum gas pressure design values ​​during the operation of the gas storage (N / mm 2 ), r is the inner radius of the sealing steel plate (mm), K0 is the unit elastic resistance coefficient of the surrounding rock (N / mm 3 ), v s is the Poisson's ratio of the sealing steel plate, E s is the elastic modulus of the steel plate (N / mm 2 ), t is the thickness of the sealing steel plate;

[0069] S73: [Δσ] is the allowable stress amplitude for constant amplitude fatigue (MPa) and is calculated as follows:

[0070] When n<5×10 6 hour,

[0071]

[0072] When 5×10 6 <n≤1×10 8 hour,

[0073]

[0074] When n≥1×10 8 hour,

[0075]

[0076] Where n is the number of stress cycles, C and β are the parameters of the component and connection, Δσ L For allowable stress, it should be adopted according to the component and connection type; the specific parameter selection can refer to the "Steel Structure Design Standard" GB 50017-2017;

[0077] The calculated result should satisfy: Δδ≤γ t [Δσ], otherwise adjust the thickness t and repeat steps S6 and S7 until the thickness t meets the requirements.

[0078] The following are specific embodiments:

[0079] S1. Based on the construction scale, capacity, operating internal pressure and other engineering characteristics of the gas storage project, the cross-sectional dimensions of the cavern are determined to be a circular cavern with an inner diameter of 20m and a burial depth of 250m, and a flat cavern layout;

[0080] S2. Determine the crack width between the surrounding rock and the structure under the most unfavorable working conditions through numerical methods and other means. Specifically, based on continuous and discontinuous calculation analysis and the most unfavorable working condition analysis, the maximum crack width between the surrounding rock and the structure under Class III surrounding rock conditions under the action of the self-weight stress field at a burial depth of 250m is 1.48mm. Considering calculation errors and uneven crack expansion, the crack width of Class III surrounding rock is assumed to be 3mm.

[0081] S3, the sealing steel plate is selected from Q460R steel plate with a thickness of 8mm. According to the stress-strain characteristics of Q460R, the yield strain ε y is 2.05‰;

[0082] S4, the operating life m of the gas storage is 50 years. According to the "Technical Code for Anti-Corrosion of Building Steel Structures", the corrosion rate v is 0.05mm / a, and the maximum corrosion amount within the 50-year operating cycle is 2.5mm. In this calculation, the 50-year corrosion amount t0 is considered to be 3mm, and the corrosion allowance t1 of the steel structure is 5mm;

[0083] S5: According to the crack width, steel plate type, internal pressure and other parameters, a calculation model for sealing steel plate cross crack is established. Figure 1 As shown;

[0084] S5 specifically includes:

[0085] S51: Calculation model is established based on the local cross section of the steel plate. Figure 2As shown in the figure, local cracks are generated in the surrounding rock under high internal pressure. It is assumed that there is a 3mm cross-crack area between the 8mm / 5mm steel plate (for the short-term operation stage and the long-term operation stage, respectively, the same below) and the surrounding rock-structure. The horizontal (x), vertical (z), and longitudinal (y) lengths of the model are as follows: the steel plate thickness is 8mm / 5mm, and the horizontal length of the model is preferably 21w, or 63mm, that is, 30mm on each side of the crack width. Experience has shown that the influence of size effect can be eliminated within this range. The vertical steel plate thickness of the model is 8mm / 5mm, and the longitudinal length is 8mm / 5mm.

[0086] S52: Determine the boundary conditions for cross-joint calculations. The contact side between the steel plate and the surrounding rock-structure is subject to vertical constraints from the surrounding rock. The free side of the steel plate and the gap between the steel plate and the surrounding rock-structure are both free surfaces.

[0087] S53: Determine the external load for the cross-slot calculation. During the pressurization phase, the steel plates expand outward, and the steel plate units are subjected to tension from the steel plates on both sides. To ensure that the steel plates are in the elastic phase, the tension is taken as half of the yield strength of Q460R steel. According to the steel structure design standard, the yield strength of Q460R steel is 410 MPa, and 205 MPa is used in this calculation. At the same time, the airside of the steel plate is subjected to the internal pressure of 18 MPa due to inflation and deflation during the operation phase.

[0088] S6: Calculate the ultimate strain of the sealing steel plate under short-term operating conditions and long-term operating conditions respectively;

[0089] S6 specifically includes:

[0090] S61: Check the cross-joint of the steel plate in the short-term operation stage (the steel plate is relatively complete and the thickness is the designed thickness of 8mm). Figure 3 As shown, the maximum principal strain of the steel plate is 0.929‰;

[0091] S62: Check the cross-joint of steel plates during long-term operation (the steel plates are corroded under the influence of external environment, with a thickness of 5mm). Figure 4 As shown, the maximum principal strain of the steel plate is 1.097‰;

[0092] S63: According to the calculation results of S61 and S62, the ultimate strain of the sealing steel plate in both the short-term and long-term operation stages is less than 2.05‰, indicating that the steel plate is in the elastic stage at this time. Therefore, the local cross-slit of the steel plate will not lead to the plastic state of the steel plate, and the sealing of the gas storage can be guaranteed.

[0093] S7: Calculate the fatigue durability of the steel plate thickness;

[0094] S7 specifically:

[0095] S71: The design stable operating life of an underground gas storage facility is no less than 50 years. During the entire operating cycle, it will undergo approximately 18,000 cycles of filling and discharging, and the steel plate will also experience approximately 18,000 stress changes, which is low-cycle fatigue. Therefore, the number of cycles for the steel plate can be taken as N = 2×104;

[0096] S72: According to the characteristics of this project, the air pressure during the daily inflation and deflation phases is maintained between 8 and 18 MPa. Through numerical calculation, the maximum radial stress change Δσ generated by the steel plate is 290 MPa.

[0097] S73: According to the relevant provisions of the "Standard for Design of Steel Structures" GB 50017-2017 on fatigue analysis, the allowable stress amplitude method is used to calculate the fatigue performance of the steel plate. The stress is calculated according to the elastic state, and the constant amplitude fatigue is calculated by keeping the stress amplitude constant within the stress cycle. The calculation is as follows:

[0098] Δδ≤γ t [Δσ]

[0099] Where Δδ is fatigue durability, γ t is the correction factor for the thickness or diameter of the sealing steel plate, which can be 1.0 in this embodiment; [Δσ] is the allowable stress amplitude of constant amplitude fatigue (MPa). Since N<5×106, it can be calculated as follows:

[0100]

[0101] Where n is the number of stress cycles, C and β are the parameters of the component and connection. The steel plate components in this article can be selected according to the "steel plate" in the "main metal without joints" in the specification, taking the conservative category, C = 861 × 1012, β = 4;

[0102] S74: The allowable stress amplitude [Δσ] of the steel plate is calculated to be 541.69 MPa. According to the stress calculation results of the steel plate under long-term operating conditions, the condition Δδ≤γ is satisfied. t [Δσ], therefore, from the perspective of stress fatigue analysis, the steel plate meets the fatigue requirements.

[0103] See also Figure 5 、 Figure 6 、 Figure 7 and Figure 8An embodiment of the present invention provides an expansion joint 1 for an underground gas storage sealing steel plate 4, comprising a first connecting section 10, an expansion section 11, and a second connecting section 12 connected in sequence. The expansion section 11 has a head end 110, a middle end 111, and a tail end 112. The head end 110 is connected to the first connecting section 10, and the tail end 112 is connected to the second connecting section 12. The section from the head end 110 to the middle end 111 and the section from the tail end 112 to the middle end 111 are both arcuate sections, and at least the expansion section 11 is a deformable section. In this embodiment, the arcuate section is capable of expansion and contraction, effectively allowing the sealing steel plate 4 to expand and contract freely with changes in pressure, thereby fully adapting to deformation caused by high internal pressure and avoiding the risk of sealing failure caused by the sealing steel plate 4 entering an elastic-plastic state due to long-term exposure to high pressure. Considering the sensitivity of steel to temperature fields, especially in high-temperature environments, where thermal expansion effects can occur, leading to abnormally increased deformation of the sealing steel plates 4, the design of a ring longitudinal expansion joint 1 can effectively reduce deformation of the sealing steel plates 4 caused by temperature changes, ensuring that the overall structural stability and sealing performance of the gas storage facility are not affected. In actual applications, the deformation of the sealing steel plates 4 is affected not only by internal pressure but also by the combined effects of temperature changes. The design of a ring longitudinal expansion joint 1 can comprehensively consider both internal pressure and temperature factors, ensuring that the sealing steel plates 4 always remain within an elastic state, preventing excessive deformation of the sealing steel plates 4 while ensuring the long-term safe operation of the gas storage facility. Specifically, the expansion section 11 is a deformation section. When the sealing steel plates 4 move, they can deform by connecting the deformation sections of two adjacent sealing steel plates 4, thereby ensuring that the overall structural stability and sealing performance of the gas storage facility are not affected. The first connecting section 10 and the second connecting section 12 can also have a deformation value. The combination of the three can expand the deformation range and further improve the overall structural stability. The use of an arc segment can facilitate deformation. Preferably, a gap 13 is provided between the two arcuate segments to provide a margin for movement. Preferably, the first connecting segment 10, the telescopic segment 11, and the second connecting segment 12 are integrally formed, which improves structural stability. Preferably, the two arcuate segments are symmetrically arranged and can be of the same length. Preferably, the first connecting segment 10, the telescopic segment 11, and the second connecting segment 12 are all ductile.

[0104] See also Figure 5 、 Figure 6 、 Figure 7 and Figure 8 The embodiment of the present invention provides a method for preventing excessive deformation of a sealing steel plate of an underground gas storage, which specifically includes the following steps:

[0105] S1: Determine the allowable deformation of the sealing steel plate under internal pressure;

[0106] S11: Determine the elastic stage limit strain rate ε of the sealing steel plate based on the steel used in the compressed air energy storage underground gas storage. n ;

[0107] S12: Determine the diameter D of the gas storage reservoir. Under the internal pressure P of the gas storage reservoir, calculate the top displacement x1 and bottom displacement x2 of different surrounding rock levels. Then, the maximum strain of the sealing steel plate can be calculated as ε. max1 If ε max1 <ε n , then the steel plate of surrounding rock of this grade can be adaptively deformed; if ε max1 ≥ε n , indicating that it is necessary to set a telescopic adjuster in the sealing steel plate to release the deformation;

[0108]

[0109] Where x1 is the top displacement of different surrounding rock levels, x2 is the bottom displacement of different surrounding rock levels, and D is the diameter of the gas storage reservoir;

[0110] S2: Thermal expansion effect caused by high temperature.

[0111] S21: Steel is greatly affected by the temperature field and needs to be superimposed with the temperature load. The peak temperature T of the sealing steel plate is calculated under the external high temperature environment during the operation period. max and T min ,It should be noted that the temperature peak only reaches the peak during the ,gas filling operation. When releasing or exhaust maintenance is performed, ,the temperature of the sealing steel plate will drop to the ambient temperature.

[0112] S22: Calculate the strain ε of the sealing steel plate under temperature changes max2 If ε max2 <ε n , indicating that the generated temperature stress can offset the tensile stress of the lining steel plate under the action of internal pressure, so there is no need to consider the influence of temperature stress in the circumferential direction of the lining steel plate; if ε max2 ≥ε n , indicating that the generated temperature stress is large and cannot offset the tensile stress of the lining steel plate under the action of internal pressure. In this case, it is necessary to consider the influence of temperature stress in the circumferential direction of the lining steel plate and install a expansion adjuster in the circumferential direction. However, in the longitudinal direction, it is necessary to consider separately whether the asphalt sliding layer behind the wall has a restraining effect. If not, it is necessary to install a temperature expansion device in the longitudinal direction to release the deformation.

[0113] ε max2 =αΔt

[0114] Where α is the thermal expansion coefficient of the material of the sealing steel plate, Δt is the temperature change of the sealing steel plate, Δt=T max -T min , where T maxis the peak temperature of the sealing steel plate, T min The lowest peak value of the sealing steel plate temperature;

[0115] S3: Ring longitudinal expansion regulator that integrates deformation due to internal pressure and expansion due to temperature;

[0116] S31: Circumferential: Through the strain analysis of the sealing steel plate under the influence of internal pressure and temperature alone, the setting conditions of the circumferential expansion joint 1 for different surrounding rock levels are obtained, and then the total expansion and contraction of the circumferential expansion joint 1 is calculated;

[0117] S32: Circumferential: Determine the number of circumferential expansion joints 1 required based on the total expansion and contraction amount and the circumferential deformation distribution characteristics of the gas storage cavern;

[0118] S33: Longitudinal: Determine the number of longitudinal deformation joints based on the longitudinal deformation distribution characteristics of the gas storage cavern;

[0119] S34: Expansion adjusters are prefabricated from cold-bent steel plates. When no circumferential expansion joint is present, the adjusters are located in the center of the steel plate, forming a "straight" pattern. When a circumferential expansion joint is present, the longitudinal expansion adjusters are arranged crosswise, forming a "cross" pattern. The adjusters are positioned in the direction of the pressure source, with the free ends at the ends, and are designed based on the amount of deformation.

[0120] The following are specific embodiments:

[0121] S1: The sealing steel plate is allowed to deform under the action of internal pressure;

[0122] S11: The steel used in the compressed air energy storage underground gas storage of this project is determined to be Q460R. In order to ensure the sealing stability, the corresponding elastic stage limit strain rate is 2.05‰;

[0123] S12: Determine the diameter D of the gas storage reservoir. Under an internal pressure of 18 MPa, calculate the top displacement of 18 mm and the bottom displacement of 18 mm for different surrounding rock levels. The following formula can then be used to calculate the maximum strains of the sealing steel plates for rock levels II and III to be 2.02‰ and 4.46‰, respectively. Therefore, the steel plates for rock level II can deform adaptively, while rock level III requires a telescopic adjuster to release deformation.

[0124]

[0125] S2: Thermal expansion effect caused by high temperature.

[0126] S21: Steel is significantly affected by the temperature field and requires the addition of a temperature load. During the operating cycle, under high external temperature conditions, the peak temperatures of the sealing steel plates were calculated to be 55°C and 26°C. It should be noted that the temperature peaks only occur during aeration operations. During release or venting maintenance, the sealing steel plate temperature will drop to ambient temperature.

[0127] S22: The following formula is used to calculate the longitudinal strain of the sealing steel plate under temperature change, which is 0.42‰. Since the temperature stress and the tensile stress of the lining steel plate under internal pressure offset each other, the influence of temperature stress on the lining steel plate in the circumferential direction does not need to be considered. However, in the longitudinal direction, since the asphalt sliding layer behind the wall has no constraint effect, a temperature expansion joint needs to be installed in the longitudinal direction to release the deformation.

[0128] ε max2 =αΔt=1.2×10 -5 ×35=0.42‰

[0129] Wherein α is the thermal expansion coefficient of the material of the sealing steel plate, and Δt is the temperature change of the sealing steel plate;

[0130] S3: Ring longitudinal expansion regulator that integrates deformation due to internal pressure and expansion due to temperature;

[0131] S31: Circumferential: After analyzing the strain of the sealing steel plate under the influence of internal pressure and temperature alone, it was found that no circumferential expansion joint 1 was required for the surrounding rock of Class II; the total expansion joint 1 for the surrounding rock of Class III was 2.5‰, with a total expansion amount of 157mm;

[0132] S32: Circumferential: The maximum expansion and contraction of each joint is 40 mm. Based on the total expansion and contraction of the circumferential expansion joint 1, it is calculated that four circumferential expansion joints 1 need to be installed.

[0133] S33: Longitudinal: set a deformation joint every 200m;

[0134] S34: The expansion adjuster is prefabricated by cold-bending steel plates. When there is no circumferential expansion joint, the expansion adjuster is located in the middle of the steel plate, forming a "one" shape. When a circumferential expansion joint is set, the longitudinal expansion adjusters of the ring are arranged crosswise, forming a "cross" shape. The adjuster is set in the direction of the pressure source, and the adjuster is a free end, and is designed according to the deformation amount. According to the requirements of steel processing accuracy, transportation and assembly welding process, the longitudinal length of the steel ring is 4m, and each ring is divided into 6 steel plates, and the length of the steel plate is about 10.4m. As shown below Figures 6 to 8 shown.

[0135] See also Figures 1 to 8An embodiment of the present invention provides an underground gas storage facility, comprising the aforementioned sealing steel plate and the aforementioned expansion joint 1. The sealing steel plate is a steel plate obtained by the aforementioned method for designing the thickness of a sealing steel plate for an underground gas storage facility. The expansion joint 1 adopts the expansion joint 1 in the aforementioned embodiment of the expansion joint 1 and the embodiment of the method for preventing excessive deformation of the sealing steel plate of an underground gas storage facility. Specifically, two adjacent sealing steel plates are connected to the first connecting section and the second connecting section, respectively. The underground gas storage facility further comprises a slip layer 2 provided between the concrete and the expansion joint 1.

[0136] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for designing the thickness of a sealing steel plate for an underground gas storage, characterized in that: The steps include: Determine the steel yield strain value of the selected sealing steel plate; Under the condition that surrounding rock cracks exist outside the sealing steel plate, obtaining the ultimate strain value of the sealing steel plate during the operation period; comparing the yield strain value of the steel material with the ultimate strain value, and when the ultimate strain value is less than the yield strain value of the steel material, calculating the fatigue durability of the sealing steel plate; The required thickness of the sealing steel plate is determined according to the fatigue durability.

2. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 1, characterized in that: The method for obtaining the ultimate strain value is specifically as follows: First, a calculation model for the sealing steel plate cross-crack is established based on the crack width, sealing steel plate thickness, and pressure in the gas storage reservoir. Then, the ultimate strain value of the sealing steel plate during the operation period is calculated based on the model.

3. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 2, wherein: The ultimate strain value includes the ultimate strain value under short-term operating conditions and the ultimate strain value under long-term operating conditions. When taking the value, the larger ultimate strain value under the two conditions is selected.

4. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 3, wherein: During long-term operation, the sealing steel plate will be corroded. The maximum corrosion amount of the sealing steel plate during the operation cycle is determined based on the environmental conditions, corrosion type, corrosion rate and corrosion environment of the gas storage reservoir. When calculating the ultimate strain value under long-term operation conditions, the thickness of the sealing steel plate after deducting the maximum corrosion amount is used.

5. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 2, wherein: When the ultimate strain value is greater than or equal to the yield strain value of the steel, the thickness of the sealing steel plate is changed and the ultimate strain value is re-obtained until the newly obtained ultimate strain value is less than the yield strain value of the steel, and then the fatigue durability of the sealing steel plate is calculated.

6. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 2, wherein: The formula for the fatigue durability of the sealing steel plate is as follows: ； in For fatigue durability, is the correction factor for the thickness or diameter of the sealing steel plate, , and are the maximum stress and minimum stress in the stress cycle of the calculated part of the sealing steel plate; like Less than or equal to , then determine the required thickness of the sealing steel plate. If Greater than , then change the thickness of the sealing steel plate and re-establish the sealing steel plate cross-seam calculation model.

7. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 5, characterized in that: The calculation formula is as follows: ； in and are the maximum and minimum gas pressure design values ​​during the operation phase of the gas storage, respectively. is the inner radius of the sealing steel plate, is the unit elastic resistance coefficient of the surrounding rock, is the Poisson's ratio of the sealing steel plate, is the elastic modulus of the steel plate, is the thickness of the sealing steel plate.

8. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 5, wherein: is the allowable stress amplitude of constant amplitude fatigue, and the calculation formula is as follows: when hour, ； when hour, ； when hour, ； in is the number of stress cycles, 、 are the parameters of components and connections, is the allowable stress.

9. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 2, wherein: The method for obtaining the width of the surrounding rock crack outside the sealing steel plate is specifically as follows: Determine the cross-sectional dimensions and burial depth of the caverns according to the scale, capacity, and internal pressure of the gas storage facility; Determine the crack width of the surrounding rock cracks under the most unfavorable working conditions based on the conditions of the cavern.

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