Underground gas storage and sealing steel plate thickness design method thereof

Abstract

The invention relates to a method for designing the thickness of a sealing steel plate of an underground gas storage. The method comprises the following steps: determining a steel yield strain value of the selected sealing steel plate; under the condition that surrounding rock cracks exist outside the sealing steel plate, the limit strain value of the sealing steel plate in the operation period is obtained; the steel yield strain value is compared with the limit strain value, and when the limit strain value is smaller than the steel yield strain value, the fatigue durability of the sealing steel plate is calculated; and determining the thickness of the required sealing steel plate according to the fatigue durability. The invention further provides an underground gas storage. The steel plate obtained through the method for designing the thickness of the sealing steel plate of the underground gas storage is adopted. According to the method, the actual thickness of the sealing steel plate is comprehensively determined through the joint crossing condition and the fatigue durability condition, and compared with an existing steel plate fire toxin selection method, quantitative analysis of the reliability of the sealing steel plate is achieved, the proper steel plate thickness can be rapidly and accurately obtained, and a reliable solution can be provided for design of a steel plate sealing gas storage.

Description

Technical Field

[0001] The 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. Background Art

[0002] Compressed air energy storage technology, as an emerging energy storage method, has attracted widespread attention worldwide in recent years. Its basic principle is to compress and store air when electricity demand is low, and release compressed air to drive generators to generate electricity when electricity demand is peak, thereby achieving the storage and release of electricity. This technology is not only environmentally friendly and efficient, but also has the characteristics of long-term energy storage, which is of great significance for improving energy utilization efficiency and promoting the development of renewable energy. With the rapid development and popularization of compressed air energy storage technology, underground gas storage, as a key infrastructure in this field, has shown a continuous growth in construction demand.

[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] The underground gas storage cavern is an important part of the compressed gas energy storage power station. It is generally composed of a sealing layer, backfill concrete and surrounding rock. The sealing layer only plays a sealing role and does not bear pressure. The sealing layer can be made of thin steel plates or polymer materials. Thin steel plates have the characteristics of good compression resilience, no softening at high temperatures, and no brittle cracking at low temperatures. They are currently the preferred choice for designers when comparing domestic underground gas storage cavern engineering plans.

[0005] The main function of the compressed gas energy storage cavern sealing structure (layer) is to prevent the leakage of high-pressure air in the cavern and ensure the sealing of the cavern. Therefore, sealing is the most important performance of the compressed gas energy storage cavern sealing layer. Although the main load of the compressed gas energy storage liner cavern is the surrounding rock, the sealing layer also needs to transfer the high internal pressure to the surrounding rock, coordinate deformation with the surrounding rock, and bear certain stress and strain in the process, so the sealing layer also needs to meet its own mechanical strength requirements.

[0006] In summary, the sealing steel plate as the sealing layer should not be damaged under various complex inflation and deflation conditions, and the sealing and durability should be guaranteed, that is, it should have a certain ductility and cross-seam stiffness to ensure that the surrounding rock and structure behind the wall are in an elastic state under the crack state. The sealing and durability are greatly related to the thickness of the sealing layer, but the exact method for calculating the reliability of the sealing layer has not yet been given. It is usually selected by analogy based on experience, which is inefficient and cannot obtain a more suitable thickness of the sealing steel plate. 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 object, 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] The ultimate strain value of the sealing steel plate during the operation period is then 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 according to 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 material, the thickness of the sealing steel plate is changed and the ultimate strain value is reacquired until the newly acquired ultimate strain value is less than the yield strain value of the steel material, 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 correction factor of the thickness or diameter of the sealing steel plate, Δσ=σ max -σ min , σ max and σ min They are the maximum stress and minimum stress in the stress cycle of the sealing steel plate calculation part respectively;

[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 across the seam.

[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, 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 cavern according to the construction scale, capacity and pressure inside the gas storage reservoir;

[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 prior art, the beneficial effects of the present invention are: the actual thickness of the sealing steel plate is determined comprehensively by the seam span condition and the fatigue durability condition. Compared with the existing steel plate fire poison selection method, it realizes the quantitative analysis of the reliability of the sealing steel plate, can quickly and accurately obtain the appropriate steel plate thickness, 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-seam area in a method for designing the thickness of a sealing steel plate of an underground gas storage provided by an embodiment of the present invention;

[0040] Figure 2 A schematic diagram of a sealing steel plate cross-seam 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 the seam of a steel plate in a method for designing the thickness of a sealing steel plate of an underground gas storage 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 of 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 figure numbers: 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-sliding layer; 3-concrete; 4-sealing steel plate. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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 comprises the following steps:

[0050] S1: Determine the cross-sectional dimensions, burial depth and layout of the cavern according to the construction scale, capacity, working 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 yielding phenomenon in steel, the stress value when the plastic deformation (permanent deformation) is 0.2% is taken as the yield strength of the material. After the steel yields, although the material is not finally destroyed, it has produced a 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, according to the anti-corrosion requirements of the steel structure, the corrosion rate of the steel plate is determined to be v (mm / a), then 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: According to crack width, steel plate model, internal pressure and other parameters, a calculation model for sealing steel plate 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-slot section of the steel plate; the transverse (x), vertical (z), and longitudinal (y) lengths of the model are as follows: Assuming that the width of the surrounding rock-structure crack is w and the thickness of the steel plate is t, the transverse length of the model should be 21w, that is, 10w on each side of the crack width. It is empirically calculated that the influence of the size effect can be eliminated within this range; the vertical length of the model is the thickness of the steel plate t, and the longitudinal length can be one-third of the transverse length or the thickness t; Among them, the crack width can be obtained through continuous and discontinuous calculation analysis, and the cross-slot calculation model includes initial conditions, boundary conditions, and external loads. Specifically: ① Initial conditions: Local cracks are generated in the surrounding rock under the action of high internal pressure, and there is a cross-slot area between the steel plate and the surrounding rock-structure. ② External loads and boundary conditions: Take the local steel plate cross-slot calculation section. During the pressurization stage, the steel plate expands outward, and the steel plate unit is subjected to the tension of the steel plates on both sides. At the same time, the air side of the steel plate is subjected to the internal pressure of the gas filling and deflating during the operation stage. The side of the steel plate in contact with the surrounding rock is subject to the vertical constraint of the surrounding rock, and the other sides are free.

[0058] S52: Determine the boundary conditions for the cross-joint calculation. 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-joint calculation. During the pressurization stage, the steel plate expands outwards, and the steel plate unit is subjected to the tensile force of the steel plates on both sides. The magnitude of the tensile force can be determined according to the stress characteristics of the steel plate in the actual project. At the same time, the air side of the steel plate is subjected to the internal pressure of the inflation and deflation during the operation stage. The maximum operating internal pressure is applied to the air side 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: According to the above contents, the maximum principal strain of the steel plate in the short-term operation stage cross-seam verification (the steel plate is relatively intact and the thickness is the design thickness t) and the long-term operation stage cross-seam verification (the thickness t1 of the steel plate after corrosion under the action of the external environment) is calculated; the larger value is taken as the ultimate strain ε0 of the steel plate, and 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, and use the allowable stress amplitude method to calculate the fatigue performance of the steel plate within the specified operating life. The final steel plate thickness must meet the requirements of both the seam span calculation and the durability calculation;

[0063] S71: According to the designed stable operation life m of the gas storage, the number of cycles n of the steel plate is determined. According to the relevant provisions of the "Standard for Design of Steel Structures" GB 50017-2017 on fatigue analysis, the fatigue performance of the steel plate is calculated using the allowable stress amplitude method. The stress is calculated according to the elastic state, and the constant amplitude fatigue is kept 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 correction factor of the thickness or diameter 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 calculation part of the sealing steel plate (MPa);

[0066] S72: Δσ can be obtained by numerical calculation or estimated by 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 facility (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. According to the construction scale, capacity, working 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 the layout is a flat cavern;

[0080] S2, determine the crack width of the surrounding rock-structure under the most unfavorable working condition by numerical methods, etc. Specifically, according to the continuous and discontinuous calculation analysis, according to the most unfavorable working condition analysis, under the condition of Class III surrounding rock under the action of the self-weight stress field at a burial depth of 250m, the maximum crack width of the surrounding rock-structure is 1.48mm; considering the calculation error and the unevenness of crack expansion, the crack width of Class III surrounding rock is considered to be 3mm;

[0081] S3, the sealing steel plate is selected as Q460R, the thickness is tentatively set to 8mm, according to the stress-strain characteristics of Q460R, the yield strain ε y 2.05‰;

[0082] S4, the operating life of the gas storage is 50 years. According to the Class III light corrosion type in 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. This calculation is based on the 50-year corrosion amount t0 of 3mm, and the corrosion allowance t1 of the steel structure is 5mm;

[0083] S5: According to 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 the action of high internal pressure. It is assumed that there is a 3mm cross-crack area between the 8mm / 5mm steel plate (short-term operation stage and long-term operation stage, 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, that is, 63mm, that is, 30mm on both sides of the crack width. It is empirically calculated that the influence of the 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 the calculation of the cross-joint. The contact side between the steel plate and the surrounding rock-structure is subject to the vertical constraint of the surrounding rock. The free side of the steel plate and the free range between the steel plate and the surrounding rock-structure are both free surfaces.

[0087] S53: Determine the external load for cross-joint calculation. During the pressurization stage, the steel plate expands outward, and the steel plate unit is subjected to the tensile force of the steel plates on both sides. To ensure that the steel plate is in the elastic stage, the tensile force is half of the yield strength of Q460R steel. According to the steel structure design standard, the yield strength of Q460R steel is 410MPa, and 205MPa is used in this calculation. At the same time, the air side of the steel plate is subjected to the internal pressure of inflation and deflation during the operation stage, which is 18MPa.

[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 the steel plate during the long-term operation phase (the steel plate is corroded under the influence of the external environment, and the thickness is 5mm), such as 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 the short-term operation stage and the long-term operation stage is less than 2.05‰, which means that the steel plate is in the elastic stage at this time; therefore, the local cross-seam 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 is specifically:

[0095] S71: The design stable operation life of underground gas storage is not less than 50 years. During the entire operation period, there will be about 18,000 gas filling and discharging cycles, and the steel plate will also undergo about 18,000 stress changes, which belongs to low-cycle fatigue; therefore, the number of cycles of 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 phase 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 taken as 1.0 in this embodiment; [Δσ] is the allowable stress amplitude of constant amplitude fatigue (MPa), because 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 the connection. The steel plate component in this article can be selected according to the "steel plate" in the "main metal without connection" in the specification, and the conservative category is selected, C = 861 × 1012, β = 4;

[0102] S74: The allowable stress amplitude [Δσ] of the steel plate is calculated to be 541.69MPa. 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 8The embodiment of the present invention provides a telescopic joint 1 of a sealing steel plate 4 of an underground gas storage reservoir, comprising a first connecting section 10, a telescopic section 11 and a second connecting section 12 connected in sequence, wherein the telescopic section 11 has a head end 110, a middle end 111 and a tail end 112, wherein 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, and a section from the head end 110 to the middle end 111 and a section from the tail end 112 to the middle end 111 are both arc sections, and at least the telescopic section 11 is a deformation section. In this embodiment, the arc section can be telescopic, and can effectively allow the sealing steel plate 4 to freely telescope with the change of pressure, thereby fully adapting to the deformation caused by the high internal pressure, and avoiding the sealing steel plate 4 from entering an elastic-plastic state due to long-term exposure to high pressure, which may cause the risk of sealing failure. Considering the sensitivity of steel to temperature field, especially in high temperature environment, steel is prone to thermal expansion effect, resulting in abnormal increase in deformation of sealing steel plate 4. The design of setting ring longitudinal expansion joint 1 can effectively reduce the deformation of sealing steel plate 4 caused by temperature change, ensuring that the overall structural stability and sealing performance of gas storage are not affected; in practical application, the deformation of sealing steel plate 4 is not only affected by internal pressure, but also by the superposition of temperature change. Setting ring longitudinal expansion regulator can comprehensively consider the dual factors of internal pressure and temperature, ensuring that sealing steel plate 4 always remains in elastic state, preventing excessive deformation of sealing steel plate 4, and ensuring long-term safe operation of gas storage. Specifically, the expansion section 11 is a deformation section. When the sealing steel plate 4 moves, it can be deformed by connecting the deformation sections of two adjacent sealing steel plates 4, thereby ensuring that the overall structural stability and sealing performance of gas storage are not affected. The first connecting section 10 and the second connecting section 12 can also have a deformation amount. The combination of the three can make the deformation range larger and improve the overall structural stability. The use of arc sections can facilitate deformation. Preferably, there is a gap 13 between the two arc segments, which may have a movable margin. Preferably, the first connecting segment 10, the telescopic segment 11 and the second connecting segment 12 are an integrally formed structure, and the use of an integrally formed structure can improve the stability of the structure. Preferably, the two arc segments are symmetrically arranged, and the lengths of the two segments may also be the same. 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 reservoir, which specifically comprises the following steps:

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

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

[0107] S12: Determine the diameter D of the gas storage reservoir, and calculate the top displacement x1 and bottom displacement x2 of different surrounding rock levels under the internal pressure P of the gas storage reservoir, and then calculate the maximum strain of the sealing steel plate as ε max1 If ε max1 <ε n , then the surrounding rock steel plate of this grade can deform adaptively; 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 the release or exhaust maintenance is carried out, 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 change 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 inner lining steel plate under the action of internal pressure. Therefore, it is necessary to consider the influence of temperature stress in the circumferential direction of the inner lining steel plate and set a telescopic regulator 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 set a temperature telescopic regulator 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 It is the low peak value of the sealing steel plate temperature;

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

[0116] S31: Circumferential direction: After analyzing the strain of the sealing steel plate under the influence of internal pressure and temperature alone, the setting of the circumferential expansion joint 1 at different surrounding rock levels is obtained, and then the total expansion amount of the circumferential expansion joint 1 is calculated;

[0117] S32: Circumferential direction: according to the total expansion amount and the circumferential deformation distribution characteristics of the gas storage cavern, determine the number of circumferential expansion joints 1 that need to be set;

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

[0119] S34: The expansion adjuster is prefabricated by cold bending of steel plates. When there is no annular expansion joint, the expansion adjuster is located in the middle of the steel plate and is distributed in a "one" shape; when annular expansion joints are set, the annular longitudinal expansion adjusters are arranged crosswise and are distributed in a "cross" shape. The adjuster is set in the direction of the pressure source, the adjuster is a free end, and is designed according to the deformation amount.

[0120] The following are specific embodiments:

[0121] S1: The sealing steel plate is allowed to deform under the 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 the internal pressure of 18 MPa, calculate the top displacement of 18 mm and the bottom displacement of 18 mm for different surrounding rock levels. Then, the maximum strains of the sealing steel plates of the II and III surrounding rocks can be calculated by the following formula to be 2.02‰ and 4.46‰ respectively. Therefore, the steel plates of the II surrounding rock can deform adaptively, while the III surrounding rock needs to be equipped with a telescopic regulator to release the deformation;

[0124]

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

[0126] S21: Steel is greatly affected by the temperature field and needs to be superimposed with the temperature load. During the operation cycle, under the external high temperature environment, the peak temperature of the sealing steel plate is calculated to be 55°C and 26°C. It should be noted that the temperature peak is only reached during the gas filling operation. When releasing or exhausting maintenance, the temperature of the sealing steel plate will drop to the ambient temperature.

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

[0131] S31: Circumferential direction: After analyzing the strain of the sealing steel plate under the influence of internal pressure and temperature alone, it is found that the II-level surrounding rock does not need to be equipped with a circumferential expansion joint 1; the total expansion of the III-level surrounding rock expansion joint 1 is 2.5‰, and the total expansion amount is 157mm;

[0132] S32: Circumferential direction: The maximum expansion and contraction of each joint is 40 mm. The total expansion and contraction of the circumferential expansion joint 1 is used to calculate the number of circumferential expansion joints 1 required to be set at 4 locations;

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

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

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

[0136] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for designing the thickness of a sealing steel plate of 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 limit strain value is specifically as follows: 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; The ultimate strain value of the sealing steel plate during the operation period is then 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, characterized in that: 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.

4. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 3, characterized in that: 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.

5. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 2, characterized in that: When the ultimate strain value is greater than or equal to the yield strain value of the steel material, the thickness of the sealing steel plate is changed and the ultimate strain value is reacquired until the newly acquired ultimate strain value is less than the yield strain value of the steel material, 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, characterized in that: The formula for the fatigue durability of the sealing steel plate is as follows: Δδ≤γ t [Board] Where Δδ is fatigue durability, γ t is the correction factor of the thickness or diameter of the sealing steel plate, Δσ=σ max -σ min , σ max and σ min They are the maximum stress and minimum stress in the stress cycle of the sealing steel plate calculation part respectively; 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 across the seam.

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 of Δσ is as follows: 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, 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.

8. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 5, characterized in that: [Δσ] is the allowable stress amplitude of constant amplitude fatigue, and the calculation formula is as follows: When n<5×10 6 hour, When 5×10 6 <n≤1×10 8 hour, When n ≥ 1 × 10 8 hour, 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.

9. The method for designing the thickness of the sealing steel plate of the underground gas storage according to claim 2, characterized in that: 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 cavern according to the construction scale, capacity and pressure inside the gas storage reservoir; Determine the crack width of the surrounding rock cracks under the most unfavorable working conditions based on the conditions of the cavern.

10. An underground gas storage, characterized in that: A steel plate obtained by using the sealing steel plate thickness design method for an underground gas storage as described in any one of claims 1-9.

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