Design methods, equipment, media and cavern structure for sealing steel lining of underground gas storage caverns

Abstract

This invention relates to the field of compressed air energy storage technology, specifically to a design method, equipment, medium, and cavern structure for a sealed steel lining of an underground gas storage cavern. Under the maximum operating gas pressure of the cavern, this invention uses the reasonable wall thickness range of the steel lining in weak rock strata and the internal pressure threshold that the weak rock strata can bear as control targets. It adjusts the inner radius, thickness, and material strength grade of the steel lining to ensure that the stress of the steel lining under the maximum operating gas pressure does not exceed the allowable stress of the material, reducing the internal pressure burden on the surrounding rock and minimizing deformation. This makes the cracking of the reinforced concrete lining controllable, meeting the functional and structural safety requirements of the underground gas storage cavern under weak rock strata conditions. The design method provided by this invention offers a design basis for the application of compressed air energy storage underground gas storage caverns in weak rock strata, improving the site selection flexibility of underground gas storage caverns.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, and in particular to a design method, equipment, medium, and cavern structure for sealing steel lining of underground gas storage caverns. Background Technology

[0002] Compressed air energy storage (CASS), as a large-scale physical energy storage technology, is considered a highly promising large-scale energy storage technology due to its outstanding advantages such as large storage capacity, long lifespan, high efficiency, fast response speed, and safety and reliability. It is poised to occupy an important position in the future energy storage industry. Underground gas storage caverns are a crucial component of compressed air energy storage systems and are key to ensuring their operational performance and reliability. Gas storage caverns are tunnel-type underground cavern structures, offering advantages such as large storage capacity, flexible site selection, low construction costs, and minimal impact on the surrounding environment. After compressed air energy storage, the underground gas storage cavern bears the high internal pressure of compressed air. The surrounding rock constrains the cavern, and the internal pressure is borne jointly by the steel lining, reinforced concrete lining, and surrounding rock. The burial depth of the cavern must meet the requirements of the surrounding rock bearing the internal pressure load, constraining cavern deformation, and satisfying the cavern's uplift resistance criteria. To ensure the safety, sealing reliability, and economy of the cavern, gas storage caverns are often located in hard rock environments, such as... Figure 1 , Figure 2 As shown, the gas storage cavern typically uses a thin steel lining 3 (steel plate with a thickness of 6mm to 20mm) as a sealing layer. The steel lining 3 mainly serves a sealing function and bears less of the internal pressure. The steel lining 3 is installed along the entire length of the cavern with a uniform cross section. An integrally cast reinforced concrete lining 3 is installed between the steel lining 3 and the surrounding rock 1 as a force transmission structure layer of the sealing layer to transfer the high internal pressure load to the surrounding rock.

[0003] When the surrounding rock of an underground gas storage cavern is hard rock, the rock mass deformation modulus is large (E≥5GPa). As the main bearer of internal pressure, the surrounding rock causes less deformation of the gas storage cavern under the action of high internal pressure gas. Cracks in the concrete lining are controllable, the stress and strain level of the sealing steel lining is low, and the commonly used steel lining thickness can adapt to the alternating loads during the compressed air storage process. However, when the surrounding rock of an underground gas storage cavern is a weak rock layer (with a low rock deformation modulus, E < 5 GPa, or the weak rock layer is Class IV surrounding rock), under high internal pressure, the surrounding rock will undergo significant deformation, leading to uncontrollable cracks in the reinforced concrete lining. Excessive deformation of the sealing steel lining may cause it to yield beyond its yield strain, resulting in premature fatigue failure as the steel lining's fatigue life is less than the number of compressed air cycles in the gas storage cavern. Furthermore, the radial deformation difference at the interface between hard and soft rock causes significant additional shear stress in the steel lining. In severe cases, the stress on the lining reinforcement and steel lining may exceed the ultimate strength of the steel, leading to fracture and gas leakage. Therefore, when there are localized weak rock layers in the surrounding rock of an underground gas storage cavern, the existing standardized thin steel lining scheme will not meet the requirements. However, rejecting the site selection based on this alone would greatly reduce site selection flexibility. Therefore, it is necessary to propose a reliable and effective design method for the thickness of the sealing steel lining in areas with localized weak rock layers to ensure structural safety. Summary of the Invention

[0004] The purpose of this invention is to address the problem that the fixed dimensions of the sealing steel lining in the existing technology are difficult to adapt to the deformation under high internal pressure conditions in soft rock strata, and to provide a design method, equipment, medium, and cavern structure for sealing steel linings in underground gas storage caverns.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for designing the thickness of the sealing steel lining of an underground gas storage cavern, comprising the following steps:

[0007] The maximum wall thickness T of the steel lining under weak rock conditions and the threshold P of the internal pressure shared by the surrounding rock under weak rock conditions are preset. max ;

[0008] Based on the allowable stress σ of the steel lining material under weak rock conditions R Given the maximum operating gas pressure P in the cavern, and considering the internal pressure borne by the steel lining, calculate the minimum wall thickness t of the steel lining, and determine whether the minimum wall thickness t is less than or equal to the maximum wall thickness T.

[0009] Under the condition that t≤T, determine the thickness t1 of the steel lining, where t1≥t and t1≤T;

[0010] Calculate the circumferential stress σ of the steel lining based on the steel lining thickness t1. θ ;

[0011] Based on the circumferential stress σ of the steel lining θ Calculate the internal pressure P1 shared by the surrounding rock, and determine whether the calculated internal pressure P1 is less than or equal to the internal pressure threshold P. max ;

[0012] By adjusting the inner radius r, thickness t1, and strength grade of the steel lining material, while simultaneously satisfying t≤t1≤T and P1≤P max Under the given conditions, determine the steel strength grade, thickness, and radius of the tunnel for the steel lining in the context of weak rock formations. Adjustment can be made by adjusting only one or two of the following parameters: the inner diameter r of the steel lining, the thickness t1, and the strength grade of the steel lining material; or by adjusting all three parameters simultaneously. Changing the combination of parameters indicates adjustment.

[0013] This invention, under the maximum operating gas pressure of the cavern, uses the reasonable wall thickness range of the steel lining in weak rock strata and the internal pressure threshold that the weak rock strata can bear as control objectives. By adjusting the inner radius, thickness, and material strength grade of the steel lining, the stress of the steel lining under the maximum operating gas pressure of the cavern does not exceed the allowable stress of the material itself, reducing the internal pressure sharing of the surrounding rock and reducing the deformation of the surrounding rock. This makes the cracking of the reinforced concrete lining controllable, ensures that the steel lining meets the stress-bearing sealing requirements, reduces the shear stress at the interface between soft and hard rock, and satisfies the functional use and structural safety requirements of the underground gas storage cavern under weak rock strata conditions. The design method provided by this invention provides a design basis for the application of compressed air energy storage underground gas storage caverns under weak rock strata, which is beneficial to improving the site selection flexibility of underground gas storage caverns.

[0014] As a preferred embodiment of the present invention, the minimum wall thickness t (mm) of the steel lining is calculated by the following formula:

[0015]

[0016] In the formula, P is the maximum operating gas pressure inside the cavern, in MPa; r is the inner radius of the cavern steel lining, in mm; σ R Δ represents the allowable stress of the steel lining, in MPa; Δ represents the construction gap between the steel lining and the reinforced concrete lining, in mm; K o E1 is the unit resistance coefficient of the surrounding rock, in MPa / mm; E2 is the elastic modulus of the steel lining, in MPa; μ2 is the Poisson's ratio of the steel lining; E s2 It is the elastic modulus of the steel lining under plane strain problems, with units of MPa.

[0017] As a preferred embodiment of the present invention, the unit resistance coefficient of the surrounding rock K o We obtain it from the following formula:

[0018]

[0019] In the formula, E1 is the deformation modulus of the weak rock layer, in MPa, and μ1 is the Poisson's ratio of the weak rock layer.

[0020] As a preferred embodiment of the present invention, the step of calculating the minimum wall thickness t of the steel lining includes the following steps:

[0021] S11: First, take values ​​based on the parameters of the hard rock cavern and initially calculate the minimum wall thickness of the steel lining. The parameters include the cavern diameter of the hard rock cavern and the material strength grade of the steel lining used.

[0022] S12: Determine whether the minimum wall thickness t of the steel lining meets the requirements. If not, recalculate the minimum wall thickness t of the steel lining by reducing the inner radius r of the steel lining and increasing the strength grade of the steel lining material.

[0023] As a preferred embodiment of the present invention, the circumferential stress σ is calculated using the following formula. θ The unit is MPa:

[0024]

[0025] As a preferred embodiment of the present invention, the internal pressure P1 shared by the surrounding rock is calculated by the following formula:

[0026] In the formula, r1 is the outer radius of the reinforced concrete lining, in mm.

[0027] As a preferred embodiment of the present invention, the maximum wall thickness T is 60 mm, and the internal pressure threshold P is... max The value is taken as 50% of the total internal pressure.

[0028] In a second aspect, the present invention also provides an electronic device comprising a memory and at least one processor, the memory storing a computer program and the processor executing the computer program to implement the design method described above.

[0029] In a third aspect, the present invention also provides a computer-readable storage medium on which a computer program is stored, wherein the computer program, when executed, implements the above-described design method.

[0030] In a fourth aspect, the present invention provides a structure for an underground compressed air storage cavern under locally weak rock strata conditions, comprising a storage cavern that simultaneously penetrates both a hard rock region and a weak rock strata region. The storage cavern located in the weak rock strata region is a weak rock strata cavern, and the storage cavern located in the hard rock region is a hard rock cavern. The steel lining comprises a first steel lining and a second steel lining. The first steel lining is disposed in the hard rock cavern, and the second steel lining is disposed in the weak rock strata cavern. The cross-sectional area of ​​the second steel lining is smaller than that of the first steel lining. The first steel lining and the second steel lining are connected by a steel lining connecting section.

[0031] The compressed air underground gas storage cavern structure provided by this invention for locally weak rock strata conditions is achieved by reducing the size of the second steel lining inside the cavern in the weak rock strata compared to the first steel lining inside the cavern in the hard rock strata. A steel lining connecting section connects the first and second steel linings to form a seal. This reduces the ventilation diameter of the cavern in the weak rock strata, which increases the proportion of internal pressure shared by the steel lining within the cavern, reducing the pressure sharing effect of the surrounding rock. This, in turn, helps reduce the deformation of the weak rock strata, ensuring that the stress in the steel lining corresponding to the weak rock strata area is less than the allowable value. Cracks in the reinforced concrete lining are controllable, thus meeting the functional requirements and structural safety of the underground gas storage cavern. The aforementioned cross-sectional area refers to the projected area of ​​the cross-section enclosed by the outline of the outer wall of the steel lining, not the solid area containing the wall thickness.

[0032] The steel lining material and structural parameters of the cavern in weak rock strata can be determined using the above design method based on actual working conditions. The compressed air underground gas storage cavern structure provided by this scheme under locally weak rock strata conditions offers a new design concept for the application of compressed air energy storage underground gas storage caverns under locally weak rock strata conditions, increasing the flexibility of site selection.

[0033] In a preferred embodiment of the present invention, the thickness of the second steel lining is greater than the thickness of the first steel lining. This solution, by increasing the thickness of the steel lining in the cavern of weak rock strata, facilitates increasing the proportion of internal pressure sharing by the steel lining within the cavern, reducing the role of internal pressure sharing in the surrounding rock, and thus helping to reduce surrounding rock deformation.

[0034] As a preferred embodiment of the present invention, the excavation cross-sectional size of the hard rock cavern is larger than that of the soft rock cavern, thereby reducing the amount of excavation required for the gas storage cavern in the soft rock area, reducing the disturbance impact in the soft rock area, and facilitating construction safety.

[0035] As a preferred embodiment of the present invention, the steel lining connecting section is conical in shape, and the cross-section of the steel lining connecting section is gradually increased from the weak rock layer side to the hard rock side, which can facilitate the transition and drainage. Correspondingly, the lining thickness of the transition section is preferably gradually increased from the weak rock layer side to the hard rock side, which facilitates better force transmission.

[0036] Alternatively, as another possible implementation, the steel lining connecting section can also be set perpendicular to the axis of the gas storage cavern. The steel lining connecting section is a planar annular steel plate (viewed from the cross section of the cavern), that is, the steel lining connecting section is set along the radial direction of the cavern, and the first steel lining, the steel lining connecting section and the second steel lining together form a stepped structure.

[0037] As another possible implementation, while keeping the ventilation tunnel diameter unchanged (i.e., the inner diameters of the first and second steel linings are the same), the internal pressure sharing ratio of the steel lining in the weak rock stratum cavern can be increased by increasing the thickness of the second steel lining. This reduces the pressure sharing effect of the weak rock stratum, thereby reducing the deformation of the surrounding rock and ensuring that the stress in the steel lining corresponding to the weak rock stratum area is less than the allowable value, making the cracking of the reinforced concrete lining controllable. The first and second steel linings can be connected by a steel lining connection section or directly butt-jointed at the ends.

[0038] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0039] 1. The design method for the thickness of the sealing steel lining of the underground gas storage cavern provided by this invention can quantitatively analyze the maximum stress of the steel lining and the internal pressure shared by the surrounding rock under the maximum operating pressure, thereby quickly determining the steel strength grade, thickness and inner diameter of the cavern. This provides a design basis for the application of compressed air energy storage underground gas storage caverns under weak rock conditions and increases the flexibility of underground gas storage cavern site selection.

[0040] 2. This invention proposes a structure for underground compressed air storage caverns suitable for localized weak rock strata, providing a new design concept for the application of underground compressed air energy storage caverns under localized weak rock strata conditions and increasing the flexibility of site selection. Attached Figure Description

[0041] Figure 1 This is a cross-sectional view of a gas storage cavity in existing technology;

[0042] Figure 2 yes Figure 1 Cross-sectional view at point AA;

[0043] Figure 3 This is a flowchart illustrating a design method for sealing steel lining of an underground gas storage cavern in Example 1;

[0044] Figure 4 This is a cross-sectional view of the gas storage chamber in Example 1;

[0045] Figure 5 This is a cross-sectional view of the underground compressed air storage cavern structure under localized weak rock conditions in Example 2.

[0046] Figure 6 It is a longitudinal section of the underground compressed air storage cavern structure under localized weak rock strata conditions.

[0047] Icons: 1-surrounding rock; 2-lining; 3-steel lining; 31-first steel lining; 32-second steel lining; 33-steel lining connection section. Detailed Implementation

[0048] The present invention will now be described in detail with reference to the accompanying drawings.

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0050] Example 1

[0051] This embodiment provides a design method for the thickness of the sealing steel lining in an underground gas storage cavern. This addresses the problem that using a thin steel lining in localized soft rock conditions can lead to significant deformation under high internal gas pressure, exceeding the yield strain, and consequently significantly reducing the fatigue life of the sealing steel plate or even causing fracture. Since the cavern experiences a heating process during air compression, this embodiment does not consider the cold contraction gaps in the steel pipes or the surrounding rock. Figure 3 , Figure 4 As shown, the specific design steps are as follows:

[0052] Step 1: Determine the unit resistance coefficient K of the surrounding rock based on the survey data. o .

[0053] Due to the fact that the unit resistance coefficient K of the surrounding rock provided in the geological exploration specifications of traditional highway, railway and water conservancy and hydropower industries o The recommended value is conservative, while underground caverns subjected to high internal pressure are extremely sensitive to this parameter. Using the recommended value in the standard will result in the calculated thickness of steel lining 3 being significantly larger than the finite element calculation results, and it also contradicts existing experience. Therefore, in this embodiment, it is recommended that K... o The value was determined through in-situ testing. In the early design phase, K... o The value (MPa / mm) can be determined by the following formula (1):

[0054]

[0055] In the formula, E1 is the deformation modulus of the weak rock layer, in MPa; μ1 is the Poisson's ratio of the weak rock layer. The deformation modulus E1 and Poisson's ratio μ1 of the weak rock layer can be determined from field survey data.

[0056] Step 2: Calculate the elastic modulus E of the steel liner in the plane strain problem. s2 The result is obtained by calculation using the following formula (2):

[0057]

[0058] In the formula, E2 is the elastic modulus of steel lining 3, in MPa; μ2 is the Poisson's ratio of steel lining 3.

[0059] Step 3: Calculate K based on the steps above. o and E s2 And based on the allowable stress σ of the steel lining material itself under weak rock conditions. R Given the maximum operating gas pressure P in the cavern, the minimum wall thickness t of the steel lining 3 is further calculated using the following formula (3):

[0060]

[0061] In the formula, P is the maximum operating gas pressure of the cavern, in MPa; r is the inner radius of the cavern steel lining 3, in mm; σ R Δ represents the allowable stress of steel lining 3, in MPa; Δ represents the construction joint gap between steel lining 3 and reinforced concrete lining 2, in mm. If the concrete filling outside steel lining 3 is dense and the joint grouting is good, Δ can be taken as 0.2 mm.

[0062] For the initial calculation, all parameters can be selected based on those for hard rock caverns. If the calculated minimum wall thickness of the steel lining 3 is too large, the minimum wall thickness t of the steel lining 3 can be recalculated by reducing the inner radius r of the steel lining 3 and increasing the strength grade of the steel lining 3 material, until the calculated t is within a reasonable range. Based on current design and construction experience, to facilitate the generation, transportation, and installation of the steel lining, the wall thickness of the steel lining under soft rock conditions should not exceed 60mm. That is, the maximum wall thickness T under soft rock conditions should be 60mm, and the minimum wall thickness t should be less than or equal to 60mm.

[0063] Under normal circumstances, in soft rock cavern conditions, it is necessary to simultaneously reduce the cavern diameter and increase the strength grade of the steel lining to meet the requirements; and according to actual working conditions, the minimum wall thickness t of the steel lining under soft rock conditions is generally much greater than the conventional thickness of the thin steel lining in hard rock caverns.

[0064] Step 4: Based on K calculated in Step 1 o Based on the steel lining thickness t1 selected in the previous step, calculate the circumferential stress σ of steel lining 3. θ The calculated σ θ It must satisfy σ θ ≤σ R .

[0065] Specifically, in this embodiment, the circumferential stress σ of the steel liner 3 θ The following formula (4) is used to calculate:

[0066]

[0067] In the formula, t1 is the thickness of the steel lining, t1≥t, and t1 should not exceed the maximum wall thickness T of the steel lining 3 preset under the condition of weak rock layer (T is 60mm in this embodiment).

[0068] Step 5: Based on σ obtained in the previous step θ Calculate the internal pressure P1 shared by the surrounding rock 1, and determine whether the calculated internal pressure P1 is less than or equal to the threshold internal pressure P shared by the surrounding rock under weak rock conditions. max If the requirements are not met, the inner radius r, thickness t1, and material strength grade of steel liner 3 shall be readjusted until t≤t1≤T and P1≤P are simultaneously satisfied. max The constraints are used to determine the material strength grade, thickness, and radius of the tunnel of steel lining 3 under weak rock conditions.

[0069] Under normal circumstances, the inner diameter of the steel lining should be increased as much as possible to increase the gas storage capacity.

[0070] Specifically, the internal pressure P1 shared by the surrounding rock 1 can be calculated using the following formula (5):

[0071]

[0072] In the formula, r1 is the outer radius of the reinforced concrete lining 2.

[0073] Based on the finite element analysis results and relevant design experience, under weak rock conditions, when the internal pressure borne by the surrounding rock 1 does not exceed 50% of the total internal pressure (i.e., P1≤P), max =50%P), the cracks in the reinforced concrete lining are controllable, the deformation of the thick steel lining scheme in weak rock layer and the thin steel lining scheme in hard rock layer is similar under internal pressure conditions, and the steel lining in the transition section of the two types of surrounding rock will not generate excessive additional shear stress due to the deformation difference.

[0074] In areas with locally weak rock formations, thin steel linings need to address the challenges of excessive deformation and exceeding the yield strain. If a thicker steel lining is used, the lining thickness would reach nearly 300mm due to the large internal diameter of the cavern, posing significant difficulties for steel plate welding and installation. Therefore, a reduction in the inner diameter is necessary. This paper proposes a comprehensive approach to determining the sealing lining thickness and inner diameter of gas storage caverns in weak rock formations, controlling them within a construction-friendly range. By thickening the steel lining and reducing the diameter, the safety of gas storage in the cavern is ensured. Compared to the approximately 300mm steel lining thickness required for large-diameter caverns, the steel lining wall thickness required using the above design method is significantly reduced under the same conditions, making steel lining welding and installation easier.

[0075] It should be noted that weak rock strata refer to bedrock with particularly low strength and elastic modulus. Some rocks may still be hard, but become weak rock strata due to weathering or dense fractures and joints, such as Class IV surrounding rock. Others are simply weak due to their inherent rock type. In this paper, rock mass deformation modulus E < 5 GPa or Class IV surrounding rock is considered a weak rock stratum. Generally, engineering projects should choose sites with hard rock as much as possible when selecting cavern construction sites. However, abandoning the construction of gas storage caverns when the weak rock strata section is short greatly limits site selection. This embodiment adopts the above-mentioned design method, which can solve the stress and deformation problem of sealing steel lining and surrounding rock when there are local weak rock strata in underground gas storage caverns, increasing the flexibility of underground gas storage cavern site selection. It is particularly suitable for cavern design in sections with poor surrounding rock quality, weak and fractured surrounding rock, and sections less than 20m in length.

[0076] Example 2

[0077] Based on the steel lining design concept of Example 1 for weak rock strata conditions, it is explained that the internal pressure shared by the surrounding rock can be reduced by adjusting any one or any combination of two or three of the following methods simultaneously: reducing the inner diameter of the steel lining in the weak rock strata cavern, increasing the thickness of the steel lining in the weak rock strata cavern, and increasing the strength grade of the steel lining material in the weak rock strata cavern. This provides a design basis for the compressed air underground gas storage cavern structure provided in this embodiment under locally weak rock strata conditions. Figure 5 , Figure 6 As shown, the underground compressed air storage cavern structure under localized weak rock strata conditions includes a storage cavern that penetrates both hard rock and weak rock strata regions. The storage cavern located in the weak rock strata region is designated as a weak rock cavern, and the storage cavern located in the hard rock region is designated as a hard rock cavern. The storage cavern is constructed from the inside out with a sealing steel lining 3 and a lining 2. The steel lining 3 includes a first steel lining 31, a second steel lining 32, and a steel lining connecting section 33. The first steel lining 31 and the steel lining connecting section 33 are both located in the hard rock cavern, while the second steel lining 32 is located in the weak rock strata cavern. The cross-sectional area of ​​the second steel lining 32 is smaller than that of the first steel lining 31. The first steel lining 31 and the second steel lining 32 are connected by the steel lining connecting section 33. The steel linings of the weak rock strata cavern and the hard rock cavern are connected by the steel lining connecting section with a gradually changing cross-section, thus fulfilling the functional requirements of the underground gas storage cavern. By reducing the diameter of the cavern in the weak rock strata, the steel lining is constructed with a shape that is larger at both ends and smaller in the middle along its length. This increases the proportion of internal pressure shared by the steel lining 3 in the cavern in the weak rock strata and reduces the proportion of internal pressure shared by the weak rock strata 1. This helps to reduce the deformation of the weak rock strata 1, so that the stress of the steel lining 3 is less than the allowable value, and the cracks in the reinforced concrete lining 2 are controllable. Moreover, since the deformation of the weak rock strata is reduced, the deformation difference between the hard surrounding rock and the weak rock strata is smaller. Therefore, the additional shear stress generated by the deformation difference of the steel lining at the junction of soft and hard rock is smaller, which helps to ensure the structural safety of the gas storage cavern.

[0078] Furthermore, the pressure-sharing ratio of the second steel lining in the cavern of weak rock strata can be increased by increasing the thickness of the second steel lining 32 and increasing the strength grade of the material of the second steel lining 32, thereby reducing the deformation of the weak rock strata. The material and structural parameters of the second steel lining 32 in the cavern of weak rock strata, such as wall thickness and inner diameter, can be reasonably selected according to the design method in Example 1.

[0079] Furthermore, in this embodiment, both the first steel liner 31 and the second steel liner 32 are cylindrical structures with equal cross-sections. When the small-diameter soft rock cavern connects to the large-diameter hard rock cavern, the first steel liner 31 and the second steel liner 32 are preferably connected by a steel liner connecting section 33 with a slope of no more than 1:3. The steel liner connecting section 33 is generally conical in shape. During the butt joint, due to the difference in steel thickness, the weld should be welded into a gentle slope transition with a slope of no more than 1:2.5. In this embodiment, the excavation size of the hard rock cavern cross-section is larger than that of the soft rock cavern cross-section, reducing the amount of excavation in the soft rock area and reducing the disturbance impact in the soft rock area, which is beneficial to construction safety. The cross-sections of the hard rock cavern are basically consistent along the length direction, and the cross-sections of the soft rock cavern are also basically consistent along the length direction, which facilitates construction. The connection between the excavation cross-sections of the hard rock cavern and the soft rock cavern has a stepped structure. In this embodiment, the lining thickness corresponding to the second steel lining 32 in the soft rock cave can be set to be the same as the lining thickness corresponding to the first steel lining 31 in the hard rock cave. The thickness of the lining 2 structure within the steel lining connection section range is set to change from thick to thin from the soft rock side to the hard rock side.

[0080] It should be noted that weak rock strata refer to bedrock with particularly low strength and elastic modulus. Some rocks are still relatively hard, but become weak rock strata due to weathering or dense fractures and joints, such as Class IV surrounding rocks. Others are weak due to the inherent weakness of the rock itself. In this paper, rock mass deformation modulus E < 5 GPa or Class IV surrounding rocks are considered weak rock strata. Generally, when selecting a site for cavern construction, we should try to choose areas with hard rock. However, abandoning the construction of gas storage caverns when the weak rock strata section is short (less than 20m) greatly limits site selection. This embodiment further provides a scheme for connecting caverns in weak rock strata with hard rock caverns based on the above design method. The proposed structure provides a new design concept for the application of compressed air energy storage underground gas storage caverns under local weak rock strata conditions, increasing the flexibility of site selection.

[0081] Example 3

[0082] Based on Embodiment 1, this embodiment provides an electronic device, which includes a memory and at least one processor. The memory stores a computer program, and the processor executes the computer program to implement the design method described above.

[0083] Specifically, the processor may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application. The memory may include a mass storage device for data or instructions. For example, and not limitingly, the memory may include a hard disk drive (HDD), a floppy disk drive, a solid-state drive (SSD), flash memory, an optical disk drive, a magneto-optical disk drive, magnetic tape, or a Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, the memory may include removable or non-removable (or fixed) media. Where appropriate, the memory may be internal or external to the data processing device. In a particular embodiment, the memory is non-volatile memory. In a particular embodiment, the memory includes read-only memory (ROM) and random access memory (RAM). Where appropriate, the ROM may be a mask-programmed ROM, a programmable read-only memory (PROM), an erasable programmable read-only memory (FPROM), an electrically erasable programmable read-only memory (EFPROM), an electrically alterable read-only memory (EAROM), or flash memory, or a combination of two or more of these.Where appropriate, the RAM can be Static Random-Access Memory (SRAM) or Dynamic Random-Access Memory (DRAM). DRAM can be Fast Page Mode Dynamic Random-Access Memory (FPMDRAM), Extended Data Out Dynamic Random-Access Memory (EDODRAM), Synchronous Dynamic Random-Access Memory (SDRAM), etc.

[0084] Memory can be used to store or cache various data files that need to be processed and / or communicated, as well as possible computer program instructions executed by the processor.

[0085] The processor implements any of the methods described in the above embodiments by reading and executing computer program instructions stored in memory. In some embodiments, the electronic device may further include a communication interface and a bus. The processor, memory, and communication interface are connected via the bus and communicate with each other.

[0086] A bus, including hardware, software, or both, couples components of a computer device together. Buses include, but are not limited to, at least one of the following: data bus, address bus, control bus, expansion bus, and local bus. For example, and not as a limitation, a bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Extended Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VLB) bus, or other suitable buses, or a combination of two or more of these. Where appropriate, a bus may include one or more buses. Although specific buses are described and illustrated in the embodiments of this application, this application considers any suitable bus or interconnection.

[0087] Example 4

[0088] Based on Embodiment 1, this embodiment provides a computer-readable storage medium storing a computer program, which, when executed, implements the design method described above.

[0089] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium, and when executed, it performs the steps of the above method embodiments. When the integrated unit of the present invention is implemented as a software functional unit and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiments of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the method described in Embodiment 1 of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROMs, magnetic disks, or optical disks.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for sealing steel lining of an underground gas storage cavern, characterized in that, Includes the following steps: The maximum wall thickness T of the steel lining under weak rock conditions and the threshold P of the internal pressure shared by the surrounding rock under weak rock conditions are preset. max The maximum wall thickness T is 60 mm, and the internal pressure threshold P is... max The value is set at 50% of the total internal pressure; Based on the allowable stress of the steel lining material under weak rock conditions Given the maximum operating gas pressure P of the cavern, calculate the minimum wall thickness t of the steel lining, and determine whether the minimum wall thickness t is less than or equal to the maximum wall thickness T; The minimum wall thickness t of the steel lining is calculated using the following formula: ； ； ； In the formula, P is the maximum operating gas pressure inside the cavern, in MPa; r is the inner radius of the steel lining of the tunnel, in mm; The allowable stress of the steel lining is expressed in MPa. Construction joint between steel lining and reinforced concrete lining, in mm; K o This is the unit resistance coefficient of the surrounding rock, with units of MPa / mm; E 2 is the elastic modulus of the steel lining, in MPa, and μ2 is the Poisson's ratio of the steel lining. E s2 E1 is the elastic modulus of the steel lining under plane strain problem, in MPa; E1 is the deformation modulus of the weak rock layer, in MPa; and μ1 is the Poisson's ratio of the weak rock layer. Under the condition that t≤T, determine the thickness t1 of the steel lining, where t1≥t and t1≤T; Calculate the circumferential stress of the steel lining based on the steel lining thickness t1. The unit is MPa, circumferential stress. Calculated using the following formula: ； Based on the circumferential stress of the steel lining Calculate the internal pressure P1 shared by the surrounding rock, and determine whether the calculated internal pressure P1 is less than or equal to the internal pressure threshold P. max ; The internal pressure shared by the surrounding rock is calculated using the following formula. : The unit is MPa; In the formula, The outer radius of the reinforced concrete lining is in mm. By adjusting the inner radius r, thickness t1, and strength grade of the steel lining material, while simultaneously satisfying t≤t1≤T and P1≤P max Under the condition of weak rock strata, determine the strength grade, thickness and radius of the steel lining of the tunnel.

2. The design method for sealing steel lining of underground gas storage caverns according to claim 1, characterized in that, The steps involved in calculating the minimum wall thickness t of the steel lining are as follows: S11: First, take values ​​based on the parameters of the hard rock cavern and initially calculate the minimum wall thickness of the steel lining. The parameters include the cavern diameter of the hard rock cavern and the strength grade of the steel lining material used. S12: Determine whether the minimum wall thickness t of the steel lining meets the requirements. If not, recalculate the minimum wall thickness t of the steel lining by reducing the inner radius r of the steel lining and increasing the strength grade of the steel lining material.

3. An electronic device, characterized in that, The electronic device includes a memory and at least one processor, the memory storing a computer program, and the processor executing the computer program to implement the design method for sealing steel lining of underground gas storage caverns as described in claim 1 or 2.

4. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements the design method for sealing steel lining of underground gas storage caverns as described in claim 1 or 2.

5. A structure for an underground compressed air storage cavern under locally weak rock strata, comprising a storage cavern, wherein the storage cavern is provided with a steel lining (3) and a lining (2) sequentially from the inside to the outside, characterized in that, The gas storage cavern penetrates both the hard rock region and the soft rock stratum region. The gas storage cavern located in the soft rock stratum region is designated as a soft rock stratum cavern, and the gas storage cavern located in the hard rock region is designated as a hard rock cavern. The soft rock stratum cavern is designed with a steel lining using the underground gas storage cavern sealing steel lining design method described in claim 1 or 2. The steel lining (3) includes a first steel lining (31) and a second steel lining (32). The first steel lining (31) is installed in the hard rock cavern, and the second steel lining (32) is installed in the soft rock stratum cavern. The cross-sectional area of ​​the second steel lining (32) is smaller than that of the first steel lining (31). The first steel lining (31) and the second steel lining (32) are connected by a steel lining connecting section (33). Alternatively, the inner diameters of the first steel liner (31) and the second steel liner (32) are the same, the thickness of the second steel liner (32) is greater than the thickness of the first steel liner (31), and the first steel liner (31) and the second steel liner (32) are connected.

6. The underground compressed air storage cavern structure under locally weak rock strata as described in claim 5, characterized in that, When the cross-sectional area of ​​the second steel liner (32) is smaller than the cross-sectional area of ​​the first steel liner (31), the thickness of the second steel liner (32) is greater than the thickness of the first steel liner (31).

7. A compressed air underground gas storage cavern structure under locally weak rock strata as described in claim 5 or 6, characterized in that, When the cross-sectional area of ​​the second steel liner (32) is smaller than the cross-sectional area of ​​the first steel liner (31): The excavation cross-sectional dimensions of the hard rock cavern are larger than those of the soft rock cavern. The steel lining connecting section (33) is conical in shape, and the cross-section of the steel lining connecting section (33) gradually increases from the weak rock layer side to the hard rock side. The lining thickness of the steel lining connecting section (33) gradually decreases from the weak rock layer side to the hard rock side. Or, The steel lining connecting section (33) is a planar annular steel plate. The steel lining connecting section (33) is connected to the steel lining of the soft and hard rock caverns respectively. The steel lining connecting section (33) is set perpendicular to the axis of the gas storage cavern.

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