Underground gas storage cavern sealing steel lining design method and device, medium and cavern structure

Abstract

The invention relates to the technical field of compressed air energy storage, in particular to an underground gas storage cavern sealing steel lining design method and device, a medium and a cavern structure. Under the condition of the maximum operation gas pressure of the cavern, the reasonable wall thickness range of the steel lining under the soft rock stratum condition and the internal pressure threshold value capable of being shared by the soft rock stratum serve as control targets, the internal radius, the thickness and the material strength grade of the steel lining are adjusted, the stress of the steel lining under the maximum operation gas pressure of the cavern does not exceed the allowable stress of the material, and therefore the steel lining is not prone to deformation. Internal pressure sharing of surrounding rocks is reduced, deformation of the surrounding rocks is reduced, so that cracks of the reinforced concrete lining are controllable, and functional use and structural safety of the underground gas storage cavern under the soft rock stratum condition are met. According to the design method provided by the invention, a design basis is provided for application of the compressed air energy storage underground gas storage cavern under the soft rock stratum, and the site selection flexibility of the underground gas storage cavern is favorably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed air energy storage, and in particular to a design method, equipment, medium and cavern structure for a sealed steel liner of an underground gas storage cavern. Background Art

[0002] Compressed air energy storage, as a large-scale physical energy storage technology, is regarded as a large-scale energy storage technology with great potential due to its outstanding advantages such as large energy storage capacity, long life, high efficiency, fast response speed, safety and reliability. It will occupy an important position in the future energy storage industry. Underground gas storage caverns are an important part of the compressed air energy storage system and are the key to ensuring its operational performance and reliability. The gas storage cavern is a tunnel-type underground cavern structure with the advantages of large storage scale, flexible site selection, low construction cost and little impact on the surrounding environment. After compressed air energy storage, the underground gas storage cavern is subjected to the high internal pressure of the compressed air. The surrounding rock has a constraining effect on the cavern. The internal pressure is borne by the steel lining, reinforced concrete lining and surrounding rock. The burial depth of the cavern should meet the requirements of the surrounding rock to bear the internal pressure load, constrain the deformation of the cavern, and meet the cavern anti-lift criteria. In order to ensure the safety, sealing reliability and economy of the cavern, the gas storage cavern is often located in a hard rock environment, such as Figure 1 、 Figure 2 As shown in FIG, a thin steel lining 3 (a steel plate with a thickness of 6 mm to 20 mm) is usually used as a sealing layer in a gas storage cavern. The steel lining 3 mainly plays a sealing role and has a smaller role in bearing the internal pressure. The steel lining 3 is arranged in a uniform cross-section throughout the cavern. An integrally cast reinforced concrete lining 3 is arranged between the steel lining 3 and the surrounding rock 1 as a force-transmitting structural 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 deformation modulus is large (E≥5GPa). As the main internal pressure bearer, the surrounding rock deforms less under the action of high internal pressure gas, the concrete lining cracks 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 weak (with a low deformation modulus, E < 5 GPa, or Class IV rock), the high internal pressure in the cavern can cause significant deformation of the surrounding rock, leading to uncontrolled cracking in the reinforced concrete lining. The sealing steel lining can deform excessively, exceeding its yield strain and causing premature fatigue failure, resulting in a fatigue life shorter than the number of cycles of compressed air in the cavern. Furthermore, the radial deformation differential at the interface between the soft and hard rock creates significant additional shear stress in the steel lining. In severe cases, the stress in the lining reinforcement and steel lining can exceed the ultimate strength of the steel, leading to fracture and gas leakage. Therefore, when the surrounding rock of an underground gas storage cavern is locally weak, existing standardized thin steel lining solutions will not meet the requirements. However, if this factor is used to negate site selection, site selection flexibility is significantly reduced. Therefore, it is necessary to develop a reliable and effective design method for the sealing steel lining thickness in areas with localized weak rock to ensure structural safety. Summary of the Invention

[0004] The purpose of the present invention is to provide a design method, equipment, medium and cavern structure for a sealed steel liner of an underground gas storage cavern, in order to address the problem that the existing sealing steel liner dimensions are difficult to adapt to deformation under high internal pressure conditions in soft rock formations.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

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

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

[0008] According to the allowable stress σ of the steel lining material itself under the condition of weak rock formation R and the maximum operating gas pressure P of the cavern, taking into account that the steel lining bears part of the internal pressure, 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 of t≤T, determine the thickness of the steel lining t1, t1≥t, and t1≤T;

[0010] Calculate the hoop stress σ of the steel lining according to the steel lining thickness t1 θ ;

[0011] According to the hoop 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, while satisfying t≤t1≤T, P1≤P max Under the conditions of weak rock formations, the steel lining steel strength grade, thickness, and cavern radius are determined. Adjustments can be made to any one or two of the steel lining inner diameter r, thickness t1, and steel lining material strength grade, or all three parameters simultaneously. Changing a combination of parameters constitutes an adjustment.

[0013] Under the maximum operating gas pressure of the cavern, the present invention takes the reasonable wall thickness range of the steel lining under soft rock conditions and the internal pressure threshold that the soft rock can share as the control target. 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, thereby making the cracks in the reinforced concrete lining controllable, the steel lining meeting the force level sealing requirements, reducing the shear stress at the junction of soft and hard rocks, and meeting the functional use and structural safety of the underground gas storage cavern under soft rock conditions. The design method provided by the present invention provides a design basis for the application of compressed air energy storage underground gas storage caverns under soft rock formations, which is conducive 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] Where, P is the maximum operating gas pressure in the cavern, in MPa; r is the inner radius of the cavern steel lining, in mm; σ R is the allowable stress of the steel lining, in MPa; Δ is the construction gap between the steel lining and the reinforced concrete lining, in mm; K o 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 is the elastic modulus of the steel liner under plane strain problem, in MPa.

[0017] As a preferred solution of the present invention, the unit resistance coefficient of surrounding rock K o It is obtained by the following formula:

[0018]

[0019] Where 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, the minimum wall thickness of the steel lining is initially calculated based on the parameters of the hard rock cavern, wherein the parameters include the diameter of the hard rock cavern and the material strength grade of the steel lining;

[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 hoop stress σ is calculated by the following formula: θ , 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] Where 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 max The value is 50% of the total internal pressure.

[0028] In a second aspect, the present invention further provides an electronic device, comprising a memory and at least one processor, wherein the memory stores a computer program, and the processor is configured to execute the computer program to implement the above-mentioned design method.

[0029] In a third aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, and the computer program implements the above-mentioned design method when executed.

[0030] In a fourth aspect, the present invention provides a compressed air underground storage cavern structure under local soft rock conditions, including a gas storage cavern, wherein the gas storage cavern passes through both the hard rock area and the soft rock area, the gas storage cavern located in the soft rock area is a soft rock cavern, and the gas storage cavern located in the hard rock area is a hard rock cavern, the steel lining includes a first steel lining and a second steel lining, the first steel lining is arranged in the hard rock cavern, the second steel lining is arranged in the soft rock cavern, the cross-sectional area of ​​the second steel lining is smaller than the cross-sectional area of ​​the first steel lining, and the first steel lining and the second steel lining are connected by a steel lining connecting section.

[0031] The compressed air underground storage cavern structure provided by the present invention under the condition of locally weak rock formations is achieved by reducing the second steel lining in the weak rock formation cavern compared to the first steel lining in the hard rock formation cavern, and connecting the first steel lining and the second steel lining through a steel lining connecting section to form a seal, thereby reducing the ventilation hole diameter of the weak rock formation cavern, which is beneficial to increase the internal pressure sharing ratio of the steel lining in the weak rock formation cavern, reduce the role of the surrounding rock internal pressure sharing, and thus help reduce the deformation of the weak rock formation, so that the steel lining stress corresponding to the weak rock formation area can be less than the allowable value, the cracks in the reinforced concrete lining can be controlled, and the functional use and structural safety of the underground gas storage cavern are met. The above-mentioned cross-sectional area refers to the cross-sectional projection area occupied by the outline of the outer wall of the steel lining, not the solid area where the wall thickness is located.

[0032] The steel lining material and structural parameters within the weak rock cavern can be determined using the above-mentioned design method based on actual working conditions. The proposed compressed air underground storage cavern structure for locally weak rock formations provides a new design concept for the application of compressed air energy storage underground storage caverns in locally weak rock formations, increasing site selection flexibility.

[0033] As a preferred embodiment of the present invention, the thickness of the second steel lining is greater than that of the first steel lining. This embodiment increases the thickness of the steel lining in weak rock caverns, thereby increasing the proportion of internal pressure shared by the steel lining in the weak rock caverns and reducing the role of surrounding rock in sharing internal pressure, thereby reducing surrounding rock deformation.

[0034] As a preferred solution of the present invention, the excavation cross-sectional size of the hard rock cavern is larger than the excavation cross-sectional size of the soft rock formation cavern, which reduces the excavation amount of the gas storage cavern in the soft rock formation area, reduces the disturbance impact in the soft rock formation area, and is beneficial to construction safety.

[0035] As a preferred embodiment of the present invention, the steel lining connection section is conical, and the cross-section of the steel lining connection section is gradually set from small to large from the soft rock side to the hard rock side, which can transition and drain. Accordingly, the lining thickness corresponding to the transition section is preferably gradually set from thick to thin from the soft rock side to the hard rock side, so as to facilitate better force transmission.

[0036] Alternatively, as another possible implementation method, the steel lining connection section may also be arranged perpendicular to the axis of the gas storage cavern, and the steel lining connection section is a flat annular steel plate (seen from the cross section of the cavern), that is, the steel lining connection section is arranged along the radial direction of the cavern, and a stepped structure is formed between the first steel lining, the steel lining connection section and the second steel lining.

[0037] As another possible implementation, while maintaining the same ventilation hole diameter (i.e., the inner diameter of the first and second steel liners is the same), the thickness of the second steel liner in the weak rock cavern can be increased to increase the proportion of internal pressure shared by the steel liner in the weak rock cavern, thereby reducing the effect of the weak rock internal pressure sharing, thereby reducing deformation of the surrounding rock, and reducing the corresponding steel liner stress in the weak rock region to less than the allowable value, thereby controlling cracks in the reinforced concrete lining. The first and second steel liners can be connected by a steel liner connecting section, or they can be directly butted 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 sealed steel lining of an underground gas storage cavern provided by the present 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 and thickness of the steel lining and the inner diameter of the cavern. This provides a design basis for the application of compressed air energy storage underground gas storage caverns in soft rock formations and increases the flexibility of underground gas storage cavern site selection.

[0040] 2. The present invention proposes a compressed air underground storage cavern structure suitable for use in local soft rock formations, providing a new design concept for the application of compressed air energy storage underground storage caverns in local soft rock formations and increasing the flexibility of site selection. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a cross-sectional view of a gas storage cavern in the prior art;

[0042] Figure 2 yes Figure 1 Cross-section at AA in FIG;

[0043] Figure 3 This is a schematic flow chart of a method for designing a sealed steel lining for an underground gas storage cavern in Example 1;

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

[0045] Figure 5 is a cross-sectional view of the compressed air underground storage cavern structure under the condition of locally weak rock formations in Example 2;

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

[0047] Icon: 1-surrounding rock; 2-lining; 3-steel lining; 31-first steel lining; 32-second steel lining; 33-steel lining connection section. DETAILED DESCRIPTION

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

[0049] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present 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 only used to explain the present invention and are not intended to limit the present invention.

[0050] Example 1

[0051] This embodiment provides a design method for the thickness of the steel lining of an underground gas storage cavern to address the problem that a thin steel lining solution in local soft rock conditions will cause significant deformation under the high internal pressure of the cavern gas, exceeding the yield strain, resulting in a significant reduction in the fatigue life of the sealing steel plate or, in severe cases, fracture. Since the temperature in the cavern increases during the air compression process, this embodiment does not consider the cold shrinkage gaps in the steel pipe and the surrounding rock, such as Figure 3 、 Figure 4 As shown, the specific design steps are as follows:

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

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

[0054]

[0055] Where E1 is the deformation modulus of the weak rock formation, in MPa; μ1 is the Poisson's ratio of the weak rock formation. The deformation modulus E1 and Poisson's ratio μ1 of the weak rock formation can be determined based on on-site survey data.

[0056] Step 2: Calculate the elastic modulus E of the steel lining for the plane strain problem s2 Calculated by the following formula (2):

[0057]

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

[0059] Step 3: K calculated according to the above steps o and E s2 , and according to the allowable stress σ of the steel lining material itself under the condition of weak rock formation R and the maximum operating gas pressure P of the cavern, the minimum wall thickness t of the steel lining 3 is further calculated by the following formula (3):

[0060]

[0061] Where, 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 is the allowable stress of steel lining 3, in MPa; Δ is the construction gap between steel lining 3 and reinforced concrete lining 2, in mm. If the concrete outside the steel lining 3 is densely filled and the joints are well grouted, Δ can be 0.2 mm.

[0062] During the first 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 production, transportation, and installation of the steel lining, the wall thickness of the steel lining in soft rock conditions should not exceed 60mm. That is, the maximum wall thickness T in soft rock conditions is 60mm, and the minimum wall thickness t should be less than or equal to 60mm.

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

[0064] Step 4: K calculated according to step 1 o And according to the steel lining thickness t1 selected in the previous step, calculate the hoop stress σ of steel lining 3 θ The calculated σ θ Must satisfy σ θ ≤σ R .

[0065] Specifically, in this embodiment, the hoop stress σ of the steel lining 3 is θ Calculated by the following formula (4):

[0066]

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

[0068] Step 5: According to the 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 internal pressure threshold P shared by the surrounding rock under the condition of weak rock formation. max If the requirements are not met, readjust the inner radius r, thickness t1 and material strength grade of steel lining 3 until t≤t1≤T, P1≤P max The constraints of the material strength grade, thickness and radius of the cavern of the steel lining 3 under the condition of soft rock formation are determined.

[0069] Normally, in order to increase the gas storage capacity, the inner diameter of the steel lining should be increased as much as possible under permitted conditions.

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

[0071]

[0072] Where r1 is the outer radius of reinforced concrete lining 2.

[0073] According to the finite element analysis results and relevant design experience, under the condition of soft rock formation, when the internal pressure shared by the surrounding rock 1 does not exceed 50% of the total internal pressure (i.e. P1≤P max =50%P), the cracks in reinforced concrete lining 2 are controllable, the deformation of the thick steel lining scheme in soft rock layer and the thin steel lining scheme in hard rock under internal pressure conditions are similar, and the steel linings in the transition section between the two types of surrounding rock will not generate excessive additional shear stress due to the deformation difference.

[0074] In the case of locally weak rock formations, thin steel linings must address the challenges of excessive deformation and exceeding the yield strain of the weak rock formations. If a thickened steel lining is used, the steel lining thickness will reach nearly 300mm due to the large inner diameter of the cavern, combined with corresponding calculations. This will make welding and installation of the steel plates extremely difficult, so the inner diameter needs to be appropriately reduced. This article comprehensively determines the thickness and inner diameter of the sealed lining of the gas storage cavern in the weak rock formation area under the conditions of reducing the inner diameter and improving the steel grade, controlling it within a thickness range that is convenient for construction. By thickening the steel lining and reducing the diameter, the safety of the cavern gas storage is ensured. Compared to the steel lining thickness of approximately 300mm required under large cavern diameter conditions, the steel lining wall thickness required by the above design method under the same conditions is significantly reduced, making it more convenient for steel lining welding and installation.

[0075] It should be noted that weak rock formations refer to bedrock with particularly low strength and elastic modulus. Some rock types are still hard, but become weak rock formations due to weathering or dense cracks and joints, such as Class IV surrounding rock. Some are formed because the rock type itself is weak. In this article, rock deformation modulus E < 5GPa or Class IV surrounding rock is regarded as weak rock formation. Usually, when selecting a site for cavern construction, engineering projects should try to choose a place with hard rock properties. However, when the section of the weak rock formation is not long, abandoning the construction of the gas storage cavern greatly limits the site selection. This embodiment adopts the above-mentioned design method to solve the stress and deformation problem of the sealing steel lining and surrounding rock when there are local weak rock formations in the underground gas storage cavern, which increases the flexibility of the site selection of the underground gas storage cavern. It is particularly suitable for the design of caverns with poor local surrounding rock sections, weak and broken surrounding rock sections, and sections with a length of less than 20m.

[0076] Example 2

[0077] Based on the design concept of steel lining under weak rock conditions in Example 1, it is explained that the surrounding rock shared internal pressure can be reduced by reducing the inner diameter of the steel lining in the weak rock cavern, increasing the thickness of the steel lining in the weak rock cavern, and improving the strength grade of the steel lining material in the weak rock cavern, or by adjusting any one of the following methods, or any combination of two or all three simultaneously. This provides a design basis for the structure of a compressed air underground storage cavern under local weak rock conditions in this embodiment. Figure 5 、 Figure 6 As shown, the structure of a compressed air underground storage cavern under localized weak rock conditions includes a storage cavern that penetrates both hard rock and weak rock regions. The storage cavern located in the weak rock region is a weak rock cavern, while the storage cavern located in the hard rock region is a hard rock cavern. The storage cavern is sequentially provided with a sealing steel liner 3 and a lining 2 from the inside out. The steel liner 3 comprises a first steel liner 31, a second steel liner 32, and a steel liner connecting section 33. The first steel liner 31 and the steel liner connecting section 33 are both provided in the hard rock cavern, while the second steel liner 32 is provided in the weak rock cavern. The cross-sectional area of ​​the second steel liner 32 is smaller than that of the first steel liner 31. The first steel liner 31 and the second steel liner 32 are connected by the steel liner connecting section 33. The steel liner connecting section, with its gradually varying cross-section, connects the steel liners of the soft rock cavern and the hard rock cavern, thus meeting the functional requirements of the underground gas storage cavern. By reducing the diameter of the cavern in the weak rock formation, the steel lining is constructed in a structure that is larger at both ends and smaller in the middle along the length direction, which is beneficial to increasing the internal pressure sharing ratio of the steel lining 3 in the cavern in the weak rock formation and reducing the internal pressure sharing ratio of the weak rock formation 1, thereby helping to reduce the deformation of the weak rock formation 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 formation is reduced, the deformation difference between the hard surrounding rock and the weak rock formation is smaller, so the additional shear stress generated by the deformation difference on the steel lining at the junction of the soft and hard rocks is smaller, which is beneficial to ensuring the structural safety of the gas storage cavern.

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

[0079] Furthermore, in this embodiment, both the first steel liner 31 and the second steel liner 32 are cylindrical in shape with uniform cross-sections. When a small-diameter soft rock cavern is connected to a large-diameter hard rock cavern, the first and second steel liners 31 and 32 are preferably connected by a steel liner connecting section 33 with a slope of no more than 1:3, and the steel liner connecting section 33 is generally conical. Due to the different steel thicknesses during connection, the weld seam should be formed into a smooth slope transition with a slope of no more than 1:2.5. In this embodiment, the excavation dimensions of the hard rock cavern section are larger than those of the soft rock cavern section, reducing the amount of excavation of the gas storage cavern in the soft rock region and the impact of disturbances in the soft rock region, thereby facilitating construction safety. The cross-sections of the hard rock cavern section and the soft rock cavern section are substantially uniform along their length, facilitating construction. The junction between the hard rock cavern section and the soft rock cavern section is a stepped structure. In this embodiment, the lining thickness corresponding to the second steel lining 32 in the soft rock cavern can be set to be consistent with the lining thickness corresponding to the first steel lining 31 in the hard rock cavern, and the thickness of the lining 2 structure within the steel lining connection section 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 formations refer to bedrock with particularly low strength and elastic modulus. Some rock types are still hard, but become weak rock formations due to weathering or dense cracks and joints, such as Class IV surrounding rock. Some are formed because the rock type itself is weak. In this article, rock deformation modulus E < 5GPa or Class IV surrounding rock is regarded as weak rock formation. Usually, when selecting a site for cavern construction, we should try to choose a place with hard rock properties. However, when the section of the weak rock formation is not long (less than 20m), abandoning the construction of the gas storage cavern greatly limits the site selection. Based on the above design method, this embodiment further provides a scheme for connecting the weak rock formation cavern with the hard rock cavern. The proposal of this structure provides a new design concept for the application of compressed air energy storage underground gas storage caverns under local weak rock formation conditions, which increases the flexibility of site selection.

[0081] Example 3

[0082] Based on Example 1, this embodiment provides an electronic device, which includes a memory and at least one processor, wherein the memory stores a computer program, and the processor is configured to execute the computer program to implement the above-mentioned design method.

[0083] Specifically, the above-mentioned processor may include a central processing unit (CPU), or an application-specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of an embodiment of the present application. Among them, the memory may include a large-capacity memory for data or instructions. For example, but not limitation, the memory may include a hard disk drive (HDD), a floppy disk drive, a solid-state drive (SSD), a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive or a combination of two or more of these. Where appropriate, the memory may include a removable or non-removable (or fixed) medium. Where appropriate, the memory may be inside or outside the data processing device. In a specific embodiment, the memory is a non-volatile memory. In a specific embodiment, the memory includes a read-only memory (ROM) and a random access memory (RAM). Where appropriate, the ROM may be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (FPROM), an electrically erasable PROM (EFPROM), an electrically alterable ROM (EAROM) or a flash memory (FLASH), or a combination of two or more of these.Under appropriate circumstances, the RAM can be a static random access memory (SRAM) or a dynamic random access memory (DRAM), where the DRAM can be a fast page mode dynamic random access memory (FPMDRAM), an extended data output dynamic random access memory (EDODRAM), a synchronous dynamic random access memory (SDRAM), etc.

[0084] The memory may be used to store or cache various data files required for processing and / or communication, as well as possible computer program instructions executed by the processor.

[0085] The processor implements any of the methods in the above embodiments by reading and executing computer program instructions stored in the 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, which includes hardware, software, or both, couples components of a computer device to each other. Buses include, but are not limited to, at least one of the following: a data bus, an address bus, a control bus, an expansion bus, and a local bus. By way of example and not 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 the above. Where appropriate, a bus may include one or more buses. Although embodiments herein describe and illustrate a particular bus, this application contemplates any suitable bus or interconnect.

[0087] Example 4

[0088] Based on Example 1, this embodiment provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed, the above-mentioned design method is implemented.

[0089] Those skilled in the art will understand that all or part of the steps of the above-mentioned method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiment are executed. When the above-mentioned integrated unit of the present invention is implemented in the form of 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 embodiment of the present invention or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the method described in Example 1 of the present invention. The aforementioned storage medium includes: various media that can store program codes, 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 in the scope of protection of the present invention.

Claims

1. A method for designing a sealed steel lining for an underground gas storage cavern, characterized in that: The following steps are involved: The maximum wall thickness T of the preset steel lining under soft rock conditions and the internal pressure threshold P shared by the surrounding rock under soft rock conditions max ; According to the allowable stress σ of the steel lining material itself under the condition of soft rock formation R and 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; Under the condition of t≤T, determine the steel lining thickness t1, t1≥t, and t1≤T; Calculate the hoop stress σ of the steel lining according to the steel lining thickness t1 θ ; According to the hoop 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 ; By adjusting the inner radius r, thickness t1 and strength grade of the steel lining, while satisfying t≤t1≤T, P1≤P max Under the conditions of soft rock formations, determine the strength grade, thickness of the steel lining and the radius of the cavern.

2. The method for designing a sealed steel lining for an underground gas storage cavern according to claim 1, characterized in that: The minimum wall thickness t of the steel lining is calculated by the following formula: Where, P is the maximum operating gas pressure in the cavern, in MPa; r is the inner radius of the cavern steel lining, in mm; σ R is the allowable stress of the steel lining, in MPa; Δ is the construction gap between the steel lining and the reinforced concrete lining, in mm; K o 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 is the elastic modulus of the steel lining under plane strain problem, the unit is MPa, E1 is the deformation modulus of the weak rock formation, the unit is MPa, and μ1 is the Poisson's ratio of the weak rock formation.

3. The method for designing a sealed steel lining for an underground gas storage cavern according to claim 2, characterized in that: The steps for calculating the minimum wall thickness t of the steel lining include the following steps: S11: firstly, taking values ​​according to the parameters of the hard rock cavern and initially calculating the minimum wall thickness of the steel lining, wherein 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.

4. The method for designing a sealed steel lining for an underground gas storage cavern according to claim 2, characterized in that: The hoop stress σ is calculated by the following formula θ , unit is MPa: The internal pressure P1 shared by the surrounding rock is calculated by the following formula, in MPa: Where r1 is the outer radius of the reinforced concrete lining, in mm.

5. The method for designing a sealed steel lining for an underground gas storage cavern according to any one of claims 1 to 4, characterized in that: The maximum wall thickness T is 60 mm, and the internal pressure threshold P max The value is 50% of the total internal pressure.

6. An electronic device, characterized in that: The electronic device includes a memory and at least one processor, the memory stores a computer program, and the processor is used to execute the computer program to implement the underground gas storage cavern sealing steel lining design method as described in any one of claims 1-5.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed, the method for designing a sealed steel lining for an underground gas storage cavern as described in any one of claims 1 to 5 above is implemented.

8. A compressed air underground gas storage cavern structure under local weak rock conditions, comprising a gas storage cavern, wherein the gas storage cavern is provided with a steel lining (3) and a lining (2) in sequence from the inside to the outside, characterized in that: The gas storage cavern simultaneously penetrates the hard rock area and the weak rock formation area. The gas storage cavern located in the weak rock formation area serves as a weak rock formation cavern, and the gas storage cavern located in the hard rock area serves as a hard rock cavern. The steel liner (3) comprises a first steel liner (31) and a second steel liner (32). The first steel liner (31) is arranged in the hard rock cavern, and the second steel liner (32) is arranged in the weak rock formation cavern. The cross-sectional area of ​​the second steel liner (32) is smaller than the cross-sectional area of ​​the first steel liner (31). The first steel liner (31) and the second steel liner (32) are connected via a steel liner connecting section (33). Alternatively, the inner diameters of the first steel lining (31) and the second steel lining (32) are consistent, the thickness of the second steel lining (32) is greater than the thickness of the first steel lining (31), and the first steel lining (31) and the second steel lining (32) are connected.

9. The compressed air underground storage cavern structure under local weak rock conditions according to claim 8, characterized in that: When the cross-sectional area of ​​the second steel lining (32) is smaller than the cross-sectional area of ​​the first steel lining (31), the thickness of the second steel lining (32) is greater than the thickness of the first steel lining (31).

10. The compressed air underground gas storage cavern structure under local weak rock conditions according to claim 8 or 9, characterized in that: When the cross-sectional area of ​​the second steel lining (32) is smaller than the cross-sectional area of ​​the first steel lining (31): The excavation cross-sectional size of the hard rock cavern is larger than the excavation cross-sectional size of the soft rock cavern; The steel lining connection section (33) is in a cone shape, the cross section of the steel lining connection section (33) is gradually set from small to large from the soft rock layer side to the hard rock side, and the lining thickness corresponding to the steel lining connection section (33) is gradually set from thick to thin from the soft rock layer side to the hard rock side; or, The steel lining connection section (33) is a flat annular steel plate. The steel lining connection section (33) is respectively connected to the soft rock cavern steel lining and the hard rock cavern steel lining. The steel lining connection section (33) is arranged perpendicular to the axis of the gas storage cavern.

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