Hard rock underground compressed air energy storage cavern group arrangement design method

Abstract

The application relates to a hard rock underground compressed air energy storage cavern group arrangement design method, which comprises the following steps: obtaining engineering geological parameters of a cavern field area; comprehensively considering maximum air internal pressure, combining the engineering geological parameters to determine a safe buried depth; selecting multiple feasible cavern diameters within the range of the maximum cavern diameter allowed by the safe buried depth, establishing a three-cavern model to solve a minimum safe cavern distance; using a quadratic polynomial to fit the relationship between the cavern diameter and the minimum safe cavern distance; determining an outside reserved distance of the cavern group, a cavern number allowed by land use permission and a gas storage volume according to the minimum safe cavern distance and the cavern diameter; taking the maximum gas storage volume as a criterion to determine the corresponding minimum safe cavern distance, the cavern diameter, the cavern number, the outside reserved distance and a cavern group arrangement design scheme in combination with the safe buried depth. Compared with the prior art, the application has the advantages of high durability, good safety, full utilization of gas storage land and the like.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, and in particular to a method for the layout design of underground compressed air energy storage chambers in hard rock. Background Technology

[0002] Compressed air energy storage technology is a technology that uses compressed air to store energy. Urban electricity consumption often suffers from asynchronous grid loads, and energy storage technology is crucial for the stability and security of the power system by "peak shaving and valley filling" and "smoothing fluctuations." During off-peak hours, electrical energy is used to compress air to high pressure and store it in a cavity or pressure vessel, converting electrical energy into the internal energy of the air for storage. During peak hours, the high-pressure air is released from the storage chamber and enters the combustion chamber for combustion. The expansion of the fuel during combustion drives a turbine to generate electricity.

[0003] As a crucial component of compressed air energy storage (CAES) power plants, the safety and stability of the gas storage facility directly impact the implementation of this technology. CAES gas storage facilities typically consist of rows of chambers. Unlike conventional lined chamber designs, gas storage chambers are subjected to long-term circulating internal pressure during operation, leading to cumulative damage to the serving rock. Furthermore, in a densely distributed chamber group consisting of multiple underground chambers, the stress and deformation of adjacent chambers influence each other, exhibiting a significant chamber group effect that exacerbates damage. Therefore, the design of gas storage chamber groups should avoid the formation of plastic zones in the surrounding rock. Parameters such as the burial depth, diameter, minimum safe distance between chambers, and number of chambers significantly influence the development of plastic zones in the surrounding rock. Therefore, a reasonable chamber group layout is crucial to prevent the formation of plastic zones in the surrounding rock during operation.

[0004] Existing methods for determining parameters for gas storage chamber groups suffer from two main problems. First, regarding chamber burial depth, only the uplift of the overlying rock is considered, leading to an underestimation of rock mass strength, while neglecting the safety of the surrounding rock on the sides of the chamber. Second, regarding chamber spacing, the spacing criteria used for pressureless tunnels are applied, failing to consider the unique operating conditions of the gas storage chambers under circulating internal air pressure during operation. Under compressed air cyclic loading, the surrounding rock of the chambers develops a significant plastic zone, which directly affects the stability of the gas storage chamber group. In summary, the parameter design of gas storage chamber groups relies solely on single-factor or orthogonal numerical experiments to analyze the layout parameters. While this numerical experimental method can reveal the influence of various factors on the development of the plastic zone in the surrounding rock, it cannot provide clear direction for further experiments, cannot further explore the underlying response mechanism, and cannot obtain a more general relationship between chamber spacing, diameter, and burial depth, thus exhibiting limitations specific to single projects.

[0005] Therefore, there is a need for a design method for the layout of energy storage chamber groups that can be applied to most engineering needs, has a theoretical basis, and systematically designs the burial depth, diameter, and spacing of the chambers, in order to meet the safety and stability requirements of energy storage chamber groups. Summary of the Invention

[0006] The purpose of this invention is to provide a layout design method for a group of underground compressed gas storage chambers in hard rock. Based on the geological conditions of the engineering site, a layout design method for a group of circular chambers in rows is given. This method can be used to determine the burial depth, diameter, minimum safe distance between chambers, and number of chambers under specific geological conditions. While ensuring the safety and stability of the chamber group during its operation, fewer chambers need to be excavated, and the gas storage capacity is relatively large.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for designing the layout of underground compressed gas storage chambers in hard rock includes the following steps:

[0009] Obtain the engineering geological parameters of the chamber site;

[0010] The safe burial depth is determined by comprehensively considering the maximum internal air pressure and combining engineering geological parameters.

[0011] Within the maximum allowable diameter range of safe burial depth, select multiple feasible diameters and establish a three-chamber model to solve for the minimum safe distance between chambers;

[0012] The relationship between the tunnel diameter and the minimum safe tunnel distance is fitted using a quadratic polynomial.

[0013] The reserved distance outside the chamber group, the number of chambers permitted for land use, and the gas storage volume are determined based on the minimum safe distance and diameter of the chambers.

[0014] Using the maximum gas storage capacity as the criterion, the corresponding minimum safe distance between chambers, the diameter of the chambers, the number of chambers, and the reserved distance on the outside are determined. Combined with the safe burial depth, a chamber group layout design scheme is obtained.

[0015] The engineering geological parameters include the surrounding rock grade, density, shear strength, and in-situ stress in each direction.

[0016] The determination of safe burial depth based on engineering geological parameters specifically involves:

[0017] The burial depth is initially determined based on the calculation formula for the non-plastic zone of a single chamber;

[0018] Determine the maximum tunnel diameter within the allowable burial depth range;

[0019] Establish a single-chamber model, calculate whether a plastic zone appears in the surrounding rock based on the maximum chamber diameter and burial depth. If a plastic zone appears, increase the burial depth and redetermine the maximum chamber diameter within the allowable burial depth range until no more plastic zones appear. Then, use the currently determined burial depth as the safe burial depth.

[0020] The formula for calculating the non-plastic zone in the single chamber is as follows:

[0021]

[0022]

[0023]

[0024]

[0025] In the formula, [Z] represents the safe burial depth, Z min Z represents the minimum burial depth at which the plastic zone does not appear in the tunnel wall when the air pressure inside the tunnel is at its maximum. max Z represents the maximum burial depth at which the tunnel wall does not exhibit a plastic zone under vented conditions with zero air pressure inside the tunnel. τ The burial depth corresponds to the minimum value of the maximum shear stress in the surrounding rock under the two working conditions; ρ is the density of the surrounding rock; g is the acceleration due to gravity; -p a The maximum internal air pressure value of the chamber is given, and the stress is positive when it points to the normal direction outward of the element. ω is the internal friction angle of the surrounding rock; c is the cohesion of the surrounding rock.

[0026] The diameter of the burial chamber is less than 1 / 10 of the burial depth.

[0027] The three-chamber model includes three types of interaction relationships between the chamber groups: other chambers on the left, other chambers on the right, and chambers on both the left and right. The mutual influence between chambers separated by two or more spaces is ignored.

[0028] The reserved distance outside the chamber group is greater than or equal to 0.5 times the minimum safe chamber distance.

[0029] The number of chambers in the chamber group is:

[0030]

[0031] In the formula, W is the width of the engineering land; S is the minimum safe distance between the tunnels; [] represents the floor function.

[0032] The method for calculating the volume of the gas storage tank is as follows:

[0033] V i =n i πr i 2 L

[0034] In the formula, n is the number of chambers, r is the diameter of the chamber, and L is the length of the compressed gas energy storage chamber along its axis.

[0035] When using the layout design scheme of the chamber group, based on the determined minimum safe distance between chambers, diameter of chambers, number of chambers, reserved distance on the outside and burial depth, the gas storage chambers are symmetrically arranged on the left and right sides with the center line of the project site as the axis.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) In the design of the present invention, under the control of the safe burial depth, the surrounding rock of the chamber group remains in an elastic state regardless of the gas filling and releasing conditions, which can effectively prevent the surrounding rock from cracking; the surrounding rock strain is small, and at the same time the safety of the lining is guaranteed, thereby ensuring safety and durability under long-term operational stress cycles.

[0038] (2) In this invention, the minimum value of the maximum shear stress of the surrounding rock under two working conditions is selected as the safe burial depth, so as not to blindly increase the burial depth and reduce the excavation cost of the chamber.

[0039] (3) Under the control of the minimum safe distance between the chambers, the surrounding rock always remains in an elastic state, which can effectively prevent cracks from appearing in the surrounding rock, ensure safety and durability under long-term operational stress cycles, and at the same time minimize the land area.

[0040] (4) This invention uses a quadratic polynomial to fit the relationship between the chamber radius and the minimum safe chamber distance, and the fitting effect is good. It can be used to quickly solve the minimum safe chamber distance corresponding to any chamber diameter.

[0041] (5) The chamber group layout design method of the present invention can make full use of the gas storage land, minimize the number of excavated chambers, increase the diameter of a single chamber, and obtain the largest gas storage volume while ensuring the safety and stability of the chamber group during its operation.

[0042] (6) This invention clarifies the relationship between the burial depth of the chamber and the maximum internal gas pressure and surrounding rock parameters, as well as the relationship between the burial depth and the chamber spacing and diameter. The optimal chamber diameter and corresponding chamber spacing can be obtained according to the size of the engineering site, thereby completing the layout design of the gas storage chamber group of the system. Attached Figure Description

[0043] Figure 1 This is a flowchart of the method of the present invention;

[0044] Figure 2 This is a schematic diagram of the layout design of the chamber group of the present invention;

[0045] Figure 3 This is a schematic diagram showing the relationship between the minimum safe tunnel distance and the plastic zone of the surrounding rock.

[0046] Figure 4 A schematic diagram showing the Von mises stress-affected zone and the reserved distance on the outside of the chamber group;

[0047] Figure 5 This is a schematic diagram illustrating the relationship between the tunnel diameter and the minimum safe tunnel distance in an embodiment of the present invention;

[0048] The attached diagram is labeled as follows: 1-width of the chamber area, 2-length of the chamber area, 3-safe burial depth, 4-diameter of the chamber, 5-minimum safe distance between chambers, 6-reserved distance outside the chamber group, 7-number of chambers. Detailed Implementation

[0049] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0050] This embodiment provides a method for the layout design of a group of underground compressed gas storage chambers in hard rock, such as... Figure 1 As shown, it includes the following steps:

[0051] S1. Conduct engineering geological surveys of the chamber site to obtain engineering geological parameters of the chamber site, including surrounding rock grade, density, shear strength, and in-situ stress in various directions.

[0052] Specifically, the site selection for the chamber is carried out based on the geotechnical engineering investigation report. The preliminary site selection must meet the requirements of surrounding rock grade II or above, and the existence of a hard, thick or dense layer of rock with intact rock mass, undeveloped joints, and good integrity within an appropriate burial depth below the surface.

[0053] like Figure 2 As shown, the engineering site of the chamber in this embodiment is rectangular, with a width of 1 and a length of 2; the exterior of the chamber is circular. According to the geotechnical investigation report, the direction of the maximum horizontal principal stress at the predetermined burial depth is selected as the direction of the chamber axis. The horizontal principal stress direction orthogonal to this direction on the horizontal plane is the direction of the horizontal principal stress in the chamber cross-section. The lateral pressure coefficient is calculated using the formula λ = S. h / S v ;

[0054] In the formula, λ is the pressure measurement coefficient, which is usually greater than 1 for chambers with a burial depth of less than 300 meters; S v S represents the vertical stress around the perimeter of the chamber. h The horizontal principal stress is the cross-sectional stress of the chamber.

[0055] Determine the length and width of the project site, where the length direction is the direction of the tunnel axis and the width direction is the direction of the cross-sectional layout of the tunnel group.

[0056] S2. Determine the safe burial depth by comprehensively considering the maximum internal air pressure and combining it with engineering geological parameters.

[0057] like Figure 2 As shown, the safe burial depth 3 is determined by the maximum internal air pressure, the surrounding rock parameters of the site, and the ground stress. The maximum internal air pressure is determined according to the planned installed capacity of the energy storage project, and its magnitude ranges from several megapascals to tens of megapascals.

[0058] Specifically, it includes the following steps:

[0059] S21. The burial depth is initially determined based on the calculation formula for the non-plastic zone of a single chamber.

[0060] The compressed air energy storage chamber is designed for two operating conditions: no internal air pressure and maximum internal air pressure. When there is no internal air pressure, a plastic zone will form in the surrounding rock at greater depths. When the internal air pressure reaches the maximum internal air pressure, a plastic zone will form in the surrounding rock at less depths. The presence of a plastic zone in the surrounding rock results in greater strain, making it prone to cracking and affecting the safety and stability of the chamber.

[0061] Therefore, the formula for calculating the non-plastic zone in a single chamber is:

[0062]

[0063]

[0064]

[0065]

[0066] In the formula, [Z] represents the safe burial depth, Z min Z represents the minimum burial depth at which the plastic zone does not appear in the tunnel wall when the air pressure inside the tunnel is at its maximum. max Z represents the maximum burial depth at which the tunnel wall does not exhibit a plastic zone under vented conditions with zero air pressure inside the tunnel. τ The burial depth corresponds to the minimum value of the maximum shear stress in the surrounding rock under the two working conditions; ρ is the density of the surrounding rock; g is the acceleration due to gravity; -p a The maximum internal air pressure value of the chamber is given, and the stress is positive when it points to the normal direction outward of the element. ω is the internal friction angle of the surrounding rock; c is the cohesion of the surrounding rock.

[0067] S22. Determine the maximum diameter of the burial chamber within the allowable depth range.

[0068] The radius of the chamber is determined by the burial depth; typically, the chamber diameter is less than 1 / 10 of the burial depth. In this embodiment, the radius is taken as:

[0069]

[0070] In the formula, r is the radius of the chamber, i.e., the diameter of the chamber, and Z is the burial depth.

[0071] S23. Establish a single-chamber model. Calculate whether a plastic zone appears in the surrounding rock based on the maximum chamber diameter and burial depth. If a plastic zone appears, increase the burial depth and return to step S22 to redetermine the maximum chamber diameter within the allowable burial depth range until no more plastic zones appear. Then, use the currently determined burial depth as the safe burial depth.

[0072] This safe burial depth ensures that no plastic zone appears in the surrounding rock of a single chamber during its operation; and that no plastic zone appears in the surrounding rock of a group of chambers when the diameter and spacing of the chambers are appropriate.

[0073] S3. Within the maximum allowable diameter range of the safe burial depth, select five feasible diameters, with the five radii evenly distributed between 0 and 0.05Z. Using numerical simulation, establish a three-chamber model, change the chamber spacing, and find the minimum chamber spacing that prevents the formation of a plastic zone in the surrounding rock, accurate to 0.1m, which is the minimum safe chamber spacing S. min ,like Figure 3 As shown.

[0074] The three-chamber model includes three types of interactions between chamber groups: other chambers on the left, other chambers on the right, and chambers on both the left and right. The interaction between chambers separated by two or more chambers can be ignored.

[0075] When the distance between chambers is less than the minimum safe distance, a plastic zone will form in the surrounding rock, such as... Figure 4 As shown. Therefore, the minimum safe distance between chambers is the minimum distance between chambers that does not allow the surrounding rock to form a plastic zone. Designing the distance using this method can ensure that the surrounding rock remains elastic during the operation of the chamber group, which can be considered safe.

[0076] Using this method, five sets of data on the relationship between the chamber radius and the minimum safe chamber distance can be obtained: (r1, S1), (r2, S2), (r3, S3), (r4, S4), (r5, S5).

[0077] S4. Use a quadratic polynomial to fit the relationship between the tunnel diameter and the minimum safe tunnel distance.

[0078] The relationship between the minimum safe tunnel spacing (5) and the tunnel radius was fitted using a quadratic polynomial with a five-point method. The tunnel radius was used as the independent variable, and the minimum safe tunnel spacing as the dependent variable. The five sets of data (r1, S1), (r2, S2), (r3, S3), (r4, S4), and (r5, S5) were fitted to obtain the relationship between the minimum safe tunnel spacing and the tunnel radius. Figure 5 As shown:

[0079] S min =Ar 2 +Br+C

[0080] S5. Determine the reserved distance outside the chamber group, the number of chambers permitted for land use, and the gas storage volume based on the minimum safe distance and diameter of the chambers.

[0081] The number of chambers is determined to be 7 based on the width of the project site (1) and the minimum safe distance between chambers (5).

[0082]

[0083] In the formula, W is the width of the engineering land; S is the minimum safe distance between the tunnels; [] represents the floor function.

[0084] The reserved distance of 6 on the outside of the chamber group is greater than or equal to 0.5 times the minimum safe chamber distance of 5. Considering the Von Mies stress of the surrounding rock under the condition of chamber filling with air, such as... Figure 4 As shown, it can be considered that the surrounding rock is less affected by the gas storage chambers outside 0.5 times the minimum safe distance. In this embodiment, the reserved distance outside the chamber group is 0.5 times the minimum safe distance.

[0085] Within the range of 0 to 0.05Z, the chamber radius r is taken every 0.1m. i Substitute into the fitting relation to calculate the corresponding S i and the corresponding number of chambers n i And calculate the gas storage volume using the following formula:

[0086] V i =n i πr i 2 L

[0087] In the formula, n i r represents the number of chambers. i L is the diameter of the chamber, and L is the length of the compressed gas energy storage chamber along its axis.

[0088] S6. Using the maximum gas storage capacity as the criterion, determine the corresponding minimum safe distance between chambers, the diameter of the chambers, the number of chambers, and the reserved distance on the outside. Combine this with the safe burial depth to obtain the chamber group layout design scheme.

[0089] When using the layout design scheme of the chamber group, based on the determined minimum safe distance between chambers, diameter of chambers, number of chambers, reserved distance on the outside and burial depth, the gas storage chambers are symmetrically arranged on the left and right sides with the center line of the project site as the axis.

[0090] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for designing the layout of underground compressed gas storage chambers in hard rock, characterized in that, Includes the following steps: Obtain the engineering geological parameters of the chamber site; The safe burial depth is determined by comprehensively considering the maximum internal air pressure and combining engineering geological parameters. Within the maximum allowable diameter range of safe burial depth, select multiple feasible diameters and establish a three-chamber model to solve for the minimum safe distance between chambers; The relationship between the tunnel diameter and the minimum safe tunnel distance is fitted using a quadratic polynomial. The reserved distance outside the chamber group, the number of chambers permitted for land use, and the gas storage volume are determined based on the minimum safe distance and diameter of the chambers. Using the maximum gas storage capacity as the criterion, the corresponding minimum safe distance between chambers, the diameter of the chambers, the number of chambers, and the reserved distance on the outside are determined. Combined with the safe burial depth, a chamber group layout design scheme is obtained.

2. The method for designing the layout of a group of underground compressed gas storage chambers in hard rock according to claim 1, characterized in that, The engineering geological parameters include the surrounding rock grade, density, shear strength, and in-situ stress in each direction.

3. The method for designing and arranging a group of underground compressed gas storage chambers in hard rock according to claim 1, characterized in that, The determination of safe burial depth based on engineering geological parameters specifically involves: The burial depth is initially determined based on the calculation formula for the non-plastic zone of a single chamber; Determine the maximum tunnel diameter within the allowable burial depth range; Establish a single-chamber model, calculate whether a plastic zone appears in the surrounding rock based on the maximum chamber diameter and burial depth. If a plastic zone appears, increase the burial depth and redetermine the maximum chamber diameter within the allowable burial depth range until no more plastic zones appear. Then, use the currently determined burial depth as the safe burial depth.

4. The method for designing and arranging a group of compressed gas storage chambers in hard rock underground as described in claim 3, characterized in that, The formula for calculating the non-plastic zone in the single chamber is as follows: In the formula, [Z] represents the safe burial depth, Z min Z represents the minimum burial depth at which the plastic zone does not appear in the tunnel wall when the air pressure inside the tunnel is at its maximum. max Z represents the maximum burial depth at which the tunnel wall does not exhibit a plastic zone under vented conditions with zero air pressure inside the tunnel. τ The burial depth corresponds to the minimum value of the maximum shear stress in the surrounding rock under the two working conditions; ρ is the density of the surrounding rock; g is the acceleration due to gravity; -p a The maximum internal air pressure value of the chamber is given, and the stress is positive when it points to the normal direction outward of the element. ω is the internal friction angle of the surrounding rock; c is the cohesion of the surrounding rock.

5. The method for designing the layout of a group of underground compressed gas storage chambers in hard rock according to claim 1, characterized in that, The diameter of the burial chamber is less than 1 / 10 of the burial depth.

6. The method for designing the layout of a group of underground compressed gas storage chambers in hard rock according to claim 1, characterized in that, The three-chamber model includes three types of interaction relationships between the chamber groups: other chambers on the left, other chambers on the right, and chambers on both the left and right. The mutual influence between chambers separated by two or more spaces is ignored.

7. The method for designing the layout of a group of underground compressed gas storage chambers in hard rock according to claim 1, characterized in that, The reserved distance outside the chamber group is greater than or equal to 0.5 times the minimum safe chamber distance.

8. The method for designing the layout of a group of underground compressed gas storage chambers in hard rock according to claim 1, characterized in that, The number of chambers in the chamber group is: In the formula, W is the width of the engineering land; S is the minimum safe distance between the tunnels; [] represents the floor function.

9. The method for designing the layout of a group of underground compressed gas storage chambers in hard rock according to claim 1, characterized in that, The method for calculating the volume of the gas storage tank is as follows: V i =n i πr i 2 L In the formula, n is the number of chambers, r is the diameter of the chamber, and L is the length of the compressed gas energy storage chamber along its axis.

10. The method for designing the layout of a group of underground compressed gas storage chambers in hard rock according to claim 1, characterized in that, When using the layout design scheme of the chamber group, based on the determined minimum safe distance between chambers, diameter of chambers, number of chambers, reserved distance on the outside and burial depth, the gas storage chambers are symmetrically arranged on the left and right sides with the center line of the project site as the axis.

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