Shallow coal mine soft rock roadway pressure gas energy storage bearing sealing structure and construction method

Abstract

The application discloses a shallow-buried coal mine soft rock roadway compressed air energy storage bearing sealing structure and a construction method, and belongs to the technical field of compressed air energy storage. The shallow-buried coal mine soft rock roadway compressed air energy storage bearing sealing structure is arranged in the surrounding rock of a shallow-buried coal mine soft rock roadway, is a hollow cylindrical structure, and an internal space is used for storing compressed air; the compressed air energy storage bearing sealing structure sequentially comprises a first steel sealing layer, a first sliding layer, a first reinforced concrete lining layer, a second sliding layer, a second steel sealing layer, a third sliding layer and a second reinforced concrete lining layer from the center of the roadway to the surrounding rock of the side wall of the roadway, and the second reinforced concrete lining layer is connected with an external surrounding rock layer. The application can solve the bottleneck problems of safety, sealing difficulty and high cost of compressed air energy storage of shallow-buried coal mine soft rock underground space, and provides technical support for efficient, economic and safe utilization of a large number of abandoned shallow-buried coal mine soft rock underground space resources.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, specifically to a compressed air energy storage bearing and sealing structure and construction method for soft rock roadways in shallow-buried coal mines. Background Technology

[0002] Currently, constructing pumped-storage or compressed-air energy storage power stations is an important form of large-scale utilization of underground space in closed-down coal mines. Compressed-air energy storage, in particular, has advantages such as wide applicability and low investment costs, and thus enjoys broad development prospects. Developing a reasonable load-bearing and sealing structure to ensure the stability and airtightness of compressed-air energy storage chambers in closed-down coal mines, especially those in shallow-buried coal mines with soft rock, is crucial to achieving safe and economical large-scale utilization of underground space in these mines through compressed-air energy storage technology.

[0003] In compressed gas energy storage, coal mine tunnels will be subjected to high internal gas pressure. Rock chambers experiencing similar loading conditions include air-cushion pressure regulating chambers in hydropower projects and compressed natural gas (CNG) rock storage facilities. These high-pressure rock chambers, based on their load-bearing and sealing structure characteristics, mainly fall into three categories: water-curtain unlined chambers, steel-plate-lined chambers, and flexible-lined chambers. Although CNG rock chambers employing these three types of load-bearing and sealing structures have successful engineering examples both domestically and internationally, they cannot be directly used in compressed air energy storage chambers because compressed air energy storage chambers will also be subject to frequent loading and unloading caused by gas injection and production.

[0004] Currently, research on compressed air (CSA) energy storage utilizing the soft rock underground space of shallow-buried coal mines is rarely reported. Research on using deeper, well-quality rock formations in abandoned coal mines or metal mines, as well as artificially excavated hard rock chambers as gas storage facilities, is still in the scientific experimental research and engineering demonstration stage. Among these, the artificially excavated hard rock chamber approach is becoming an important trend in the future development of CSA due to its advantages such as the wide distribution of hard rock strata, convenient site selection, and high chamber stability. Currently, the load-bearing and sealing structure design of CSA hard rock chambers largely references that of natural gas storage facilities, adopting an internally lined rock chamber form, and often employing a steel sealing layer and a concrete lining structure. The steel sealing layer can be 20-40 mm thick, and the concrete lining can be 500-600 mm thick, requiring the surrounding rock to bear a significant portion of the load. However, the aforementioned load-bearing sealing structure cannot be directly used in soft rock compressed gas storage chambers in coal mines. In hard rock gas storage facilities, the surrounding rock is one of the main load-bearing structures, while soft rock, due to its low strength, cannot serve as the primary load-bearing structure for compressed gas storage chambers. Furthermore, although the aforementioned load-bearing sealing structure is simple, it fails to fully utilize the high tensile strength of steel and the high compressive strength of concrete, resulting in an unreasonable load distribution, weak load-bearing capacity, and difficulty in ensuring sealing performance.

[0005] In summary, there is currently no suitable load-bearing and sealing structure for compressed air energy storage in soft rock underground spaces of shallow-buried coal mines. It is essential to develop a scientific and reasonable load-bearing and sealing structure to solve the key challenges of safety, stability, and airtightness of compressed air storage facilities when utilizing soft rock underground spaces in coal mines. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems in the prior art and provide a compressed air energy storage bearing and sealing structure for soft rock roadways in shallow coal mines. By cleverly arranging the interactive structural layers of the bearing and sealing (lining-sealing layer) structure, it makes full use of the high tensile strength of steel and the high compressive strength of concrete, and rationally distributes the load caused by the high internal pressure of the soft rock gas storage tank in the coal mine. This provides technical support for the efficient, economical and safe utilization of a large amount of underground space resources in closed and decommissioned shallow coal mines.

[0007] This invention provides a compressed air energy storage and bearing sealing structure for soft rock roadways in shallow-buried coal mines. The structure is a hollow cylindrical structure with internal space for storing compressed air. From the center of the roadway towards the surrounding rock of the roadway sidewall, the structure comprises, in sequence: a first steel sealing layer, a first slip layer, a first reinforced concrete lining layer, a second slip layer, a second steel sealing layer, a third slip layer, and a second reinforced concrete lining layer. The second reinforced concrete lining layer connects to the surrounding rock of the soft rock roadway in the shallow-buried coal mine.

[0008] Preferably, the thickness of the first reinforced concrete lining layer is greater than the thickness of the second reinforced concrete lining layer.

[0009] Preferably, the thickness of the first steel sealing layer is greater than the thickness of the second steel sealing layer.

[0010] Preferably, the surrounding rock is provided with anchor bolts for anchoring the surrounding rock.

[0011] Preferably, the first slip layer, the second slip layer and the third slip layer are all asphalt layers.

[0012] Preferably, both the first and second reinforced concrete lining layers are provided with multiple double-layer annular reinforcing bars along the length of the compressed air storage bearing sealing structure, and the multiple double-layer annular reinforcing bars are connected as one unit by longitudinal reinforcing bars.

[0013] Preferably, a concrete cushion layer is also sprayed between the second reinforced concrete lining layer and the surrounding rock.

[0014] This invention also discloses a construction method for the above-mentioned compressed air energy storage bearing and sealing structure for soft rock roadways in shallow-buried coal mines, comprising the following steps:

[0015] After selecting the coal mine roadway to be used, anchor bolts are first installed, and then a layer of shotcrete is sprayed to level the surface of the surrounding rock inside the roadway; at the same time, a steel reinforcement cage is installed, formwork is erected, and a second reinforced concrete lining layer is poured.

[0016] After the second reinforced concrete inner lining is demolded, the third slip layer is laid. The third slip layer is required to be laid flat and smooth. Then, the prefabricated second steel sealing layer is erected.

[0017] According to the above implementation steps, the second slip layer, the first reinforced concrete lining layer, the first slip layer and the first steel sealing layer are constructed in sequence; this process is repeated to complete the construction of the compressed air storage bearing sealing structure for soft rock roadways in shallow buried coal mines.

[0018] Preferably, depending on the actual conditions of the roadway, a waterproof coating is sprayed onto the outer surface of the first and second steel sealing layers to enhance the corrosion resistance of the steel seals.

[0019] Compared with existing technologies, the beneficial effects of this invention are as follows: The compressed air energy storage bearing and sealing structure for shallow-buried coal mine soft rock roadways of this invention, through the ingenious arrangement of interactive structural layers of the bearing and sealing (inner lining-sealing layer) structure, fully utilizes the high tensile strength of steel and the high compressive strength of concrete, rationally distributing the load caused by the high internal pressure of the coal mine soft rock gas storage tank. It allows the concrete lining layer sandwiched between the two steel sealing layers to operate with certain cracks, and allows for a certain degree of deformation of the innermost steel sealing layer. The two steel sealing layers form two sealing barriers for high-pressure air. Furthermore, compared with similar hard rock engineering designs, under the same gas storage pressure, this invention, through structural optimization, achieves stronger bearing capacity and better sealing performance of the bearing and sealing structure while maintaining almost the same total structural layer thickness. This invention can solve the bottleneck problems of safety, sealing difficulties, and high costs faced in utilizing compressed air energy storage in the underground space of shallow-buried coal mine soft rock, providing technical support for the efficient, economical, and safe utilization of a large number of decommissioned shallow-buried coal mine underground space resources. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the compressed air energy storage bearing and sealing structure for shallow buried soft rock tunnels according to the present invention;

[0021] Figure 2 This is a schematic diagram of the initial support and reinforcement of the surrounding rock according to the present invention;

[0022] Figure 3 This is a schematic diagram of the construction of the secondary reinforced concrete inner lining layer of the present invention;

[0023] Figure 4 This is a schematic diagram of the secondary steel sealing layer application and the tertiary sliding layer laying of the present invention;

[0024] Figure 5 This is a schematic diagram of the construction of the primary reinforced concrete inner lining and the laying of the secondary slip layer according to the present invention;

[0025] Figure 6 This is a schematic diagram of the one-time steel sealing layer application and one-time sliding layer laying of the present invention;

[0026] Figure 7 This is a schematic diagram of the reinforcement section of the reinforced concrete lining of the present invention;

[0027] Figure 8 This is a schematic diagram of the reinforcement arrangement of the reinforced concrete lining of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. First steel sealing layer, 2. First slip layer, 3. First reinforced concrete lining layer, 4. Second slip layer, 5. Second steel sealing layer, 6. Third slip layer, 7. Second reinforced concrete lining layer, 8. Surrounding rock, 9. Concrete cushion layer, 10. Anchor bolt, 11. Circular reinforcing steel bar, 12. Longitudinal reinforcing steel bar. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0031] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” indicate that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0032] This invention aims to develop a more rational load-bearing and sealing structure to ensure the stability and airtightness of compressed air energy storage chambers in closed-down coal mines, especially those in shallow-buried coal mines with soft rock. Based on the existing load-bearing and sealing structure of compressed air energy storage chambers in hard rock, this invention cleverly arranges the interactive structural layers of the load-bearing and sealing (lining-sealing layer) structure, fully utilizing the high tensile strength of steel and the high compressive strength of concrete. It rationally distributes the load caused by the high internal pressure of the soft rock gas storage chamber in the coal mine, achieving a higher overall load-bearing capacity and superior sealing performance while maintaining the same thickness as the existing load-bearing and sealing structure of compressed air energy storage chambers in hard rock. This is more suitable for the high requirements of stability and sealing in soft rock roadways of shallow-buried coal mines, providing technical support for the efficient, economical, and safe utilization of a large amount of underground space resources in closed-down shallow-buried coal mines.

[0033] This embodiment provides a compressed air energy storage and bearing sealing structure for soft rock roadways in shallow-buried coal mines. The structure is located within the surrounding rock 8 of the roadway, where the surrounding rock 8 conforms to the soft rock (mudstone, argillaceous sandstone, sandstone, etc.) found in shallow-buried coal mine roadways. The compressed air energy storage and bearing sealing structure is a hollow cylindrical structure, with its internal space used to store compressed air. From the center of the roadway towards the surrounding rock 8, the structure sequentially includes: a first steel sealing layer 1, a first slip layer 2, a first reinforced concrete lining layer 3, a second slip layer 4, a second steel sealing layer 5, a third slip layer 6, and a second reinforced concrete lining layer 7. The second reinforced concrete lining layer 7 connects to the external surrounding rock 8. This disclosed compressed air energy storage and bearing sealing structure for soft rock roadways in shallow-buried coal mines relates to the roadway cross-section, and both ends of the structure are equipped with plugs (sealing structures) located at the ends of the roadway.

[0034] In a preferred embodiment, the thickness of the first reinforced concrete lining layer 3 is greater than the thickness of the second reinforced concrete lining layer 7, which can adequately cope with the high compressive stress near the wall of the gas storage cavern.

[0035] In a preferred embodiment, the thickness of the first steel sealing layer 1 is greater than the thickness of the second steel sealing layer 5, which can adequately cope with the high tensile stress near the wall of the gas storage cavity.

[0036] In a preferred embodiment, the surrounding rock 8 is provided with anchor bolts 10 for anchoring the surrounding rock 8.

[0037] In another preferred embodiment, the first slip layer 2, the second slip layer 4 and the third slip layer 6 are all asphalt layers, which serve to reduce friction and prevent excessive deformation of the sealing layer caused by unevenness of the inner lining surface.

[0038] As another preferred embodiment, the first reinforced concrete inner lining layer 3 and the second reinforced concrete inner lining layer 7 are each provided with multiple double-layer annular reinforcing bars 11 along the length direction of the compressed air energy storage bearing sealing structure. The multiple double-layer annular reinforcing bars 11 are connected as one unit by longitudinal reinforcing bars 12. After the reinforcing bar skeleton is prefabricated, the first reinforced concrete inner lining layer 3 and the second reinforced concrete inner lining layer 7 can be formed by casting concrete on site.

[0039] This embodiment also discloses the construction method of the above-mentioned compressed air energy storage bearing sealing structure for soft rock roadways in shallow buried coal mines, including the following steps:

[0040] After selecting the coal mine roadway to be used, firstly, anchor bolts 10 are installed, and then a layer of shotcrete is sprayed to smooth the surface of the surrounding rock inside the roadway; at the same time, the steel reinforcement frame is installed, the formwork is erected, and the second reinforced concrete inner lining layer 7 is poured.

[0041] After the second reinforced concrete inner lining layer 7 is demolded, the third sliding layer 6 is laid. The third sliding layer 6 is required to be laid flat and smooth. Then, the prefabricated second steel sealing layer 5 is erected.

[0042] According to the above implementation steps, the second slip layer 4, the first reinforced concrete inner lining layer 3, the first slip layer 2 and the first steel sealing layer 1 are constructed in sequence; the construction of the compressed air storage bearing sealing structure for the soft rock roadway in the shallow buried coal mine is completed by repeating this process.

[0043] As an optional approach, depending on the actual conditions of the tunnel, a waterproof coating can be sprayed onto the outer surface of the first steel sealing layer 1 and the second steel sealing layer 5 to enhance the corrosion resistance of the steel seal.

[0044] like Figure 1 As shown, the compressed air energy storage bearing and sealing structure for shallow buried coal mine soft rock roadways in this embodiment includes a first steel sealing layer 1, a first sliding layer 2, a first reinforced concrete inner lining layer 3, a second sliding layer 4, a second steel sealing layer 5, a third sliding layer 6, and a second reinforced concrete inner lining layer 7, forming a cylindrical hollow cavity; the second reinforced concrete inner lining layer 7 is connected to the external surrounding rock layer 8.

[0045] The inner side of the surrounding rock 8 is sprayed with concrete layer 9 and connected to the second reinforced concrete lining layer 7; the second steel sealing layer 5 is attached to the inner side of the second reinforced concrete lining layer 7 and is bonded through the third slip layer 6; the inner and outer sides of the first reinforced concrete lining layer 3 are the first slip layer 2 and the second slip layer 4, and the inner side of the first slip layer 2 is the first steel sealing layer 1, forming a multi-layer lining-sealing interactive composite structure, namely a compressed air storage bearing and sealing structure for soft rock roadways in shallow coal mines.

[0046] like Figure 1 As shown, the surrounding rock strata are soft rocks (mudstone, argillaceous sandstone, sandstone, etc.) that conform to the shallow buried coal mine tunnels.

[0047] like Figure 2 As shown, a shotcrete cushion layer 9 is sprayed inside the surrounding rock layer, and the shotcrete cushion layer 9 is anchored to the surrounding rock 8 by anchor bolts 10.

[0048] like Figure 3 As shown, the second reinforced concrete inner lining 7 connects to the surrounding rock layer of the roadway after the initial support is completed.

[0049] like Figure 4 , Figure 5 and Figure 6 As shown, the first slip layer 2, the second slip layer 4, and the third slip layer 6 are all made of asphalt and are used to adjust the contact gap between the reinforced concrete lining and the steel sealing layer, reduce friction, and avoid excessive deformation of the sealing layer caused by unevenness of the lining surface.

[0050] like Figure 7-8 As shown, the first reinforced concrete inner lining layer 3 and the second reinforced concrete inner lining layer 7 are equipped with multiple double-layer annular reinforcing bars 11 along the length direction of the compressed air energy storage bearing sealing structure. The multiple double-layer annular reinforcing bars 11 are connected into one piece by longitudinal reinforcing bars 12.

[0051] Given the current lack of practical engineering precedents for compressed air energy storage in soft rock tunnels of shallow-buried coal mines, and referencing similar hard rock gas storage facility design, we assumed that under the required compressed air pressure conditions for energy storage in a hard rock cavern, a traditional single-layer lining-sealing structure would be designed with a 500mm reinforced concrete lining and a 20mm steel sealing layer. However, based on elasticity calculations and elastoplastic numerical analysis, we found that under the same gas storage pressure, the above-mentioned bearing-sealing structure design is not suitable for soft rock conditions in coal mines and will lead to failure of the bearing-sealing structure. Simultaneously, following the structural design principles of this embodiment, we attempted to design a two-layer concrete lining and two steel sealing layers. Numerical analysis showed that from the cavern wall outwards through multiple sealing layers and concrete lining layers, both radial compressive stress and circumferential tensile stress rapidly decrease, with higher tensile and compressive stresses limited to... In the smaller area near the tunnel wall, the thickness of the two concrete linings and steel sealing layers is designed according to the stress distribution characteristics of the gas storage tank, following the general principle that the side closer to the tunnel experiences greater stress and therefore has a larger thickness. The specific thickness values ​​of each concrete lining and steel sealing layer are determined based on the actual working conditions of the gas storage tank. For example, for a specific project, under the same gas storage pressure conditions as a hard rock tunnel with a 500mm reinforced concrete lining and a 20mm steel sealing layer bearing the sealing structure, we designed the thickness of the first steel sealing layer 1 to be 12mm, the thickness of the first reinforced concrete lining layer 3 to be 300mm, the thickness of the second steel sealing layer 5 to be 8mm, and the thickness of the second reinforced concrete lining layer 7 to be 200mm. Based on elasticity calculations and elastoplastic numerical analysis, we found that the optimized structure of this disclosure is well-suited to the soft rock conditions of the coal mine in the actual working conditions of this project. Compared to a single-layer sealing-lining structure, the interactive load-bearing sealing structure disclosed herein significantly reduces stress at corresponding locations. With a slight increase in materials (due to variations in the geometric dimensions of each layer in a multi-layer structure leading to a slight increase in steel and concrete materials), this load-bearing sealing structure can be used in soft rock conditions in coal mines to achieve high-pressure energy storage comparable to that in hard rock caverns. This represents a breakthrough in the design paradigm of high-pressure gas storage load-bearing sealing structures and has broad engineering application prospects. The load-bearing sealing structure for compressed gas storage in shallow-buried soft rock roadways of this embodiment cleverly arranges the lining (which is the main load-bearing structure) and steel sealing layer, fully utilizing the high compressive strength of concrete and the high tensile strength of steel. Simultaneously, two sealing barriers (two steel sealing layers) ensure sealing performance.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A compressed air energy storage and bearing sealing structure for soft rock roadways in shallow-buried coal mines, characterized in that, The compressed air energy storage bearing sealing structure is a hollow cylindrical structure, and its internal space is used to store compressed air. The compressed air energy storage bearing sealing structure includes, in sequence from the center of the roadway to the surrounding rock (8) of the roadway sidewall: a first steel sealing layer (1), a first slip layer (2), a first reinforced concrete lining layer (3), a second slip layer (4), a second steel sealing layer (5), a third slip layer (6), and a second reinforced concrete lining layer (7). The second reinforced concrete lining layer (7) connects to the surrounding rock (8) of the soft rock roadway in the shallow buried coal mine. The thickness of the first reinforced concrete lining layer (3) is greater than the thickness of the second reinforced concrete lining layer (7). The thickness of the first steel sealing layer (1) is greater than the thickness of the second steel sealing layer (5).

2. The compressed air storage and bearing sealing structure for shallow-buried coal mine soft rock roadways as described in claim 1, characterized in that, Anchor bolts (10) for anchoring the surrounding rock (8) are provided inside the surrounding rock (8).

3. The compressed air energy storage and bearing sealing structure for shallow-buried coal mine soft rock roadways as described in claim 1, characterized in that, The first slip layer (2), the second slip layer (4) and the third slip layer (6) are all asphalt layers.

4. The compressed air storage and bearing sealing structure for shallow-buried coal mine soft rock roadways as described in claim 1, characterized in that, The first reinforced concrete inner lining (3) and the second reinforced concrete inner lining (7) are each equipped with multiple double-layer annular reinforcing bars (11) along the length direction of the compressed air energy storage bearing sealing structure. The multiple double-layer annular reinforcing bars (11) are connected as one unit by longitudinal reinforcing bars (12).

5. The compressed air energy storage and bearing sealing structure for shallow-buried coal mine soft rock roadways as described in claim 1, characterized in that, A concrete cushion layer (9) is also sprayed between the second reinforced concrete inner lining layer (7) and the surrounding rock (8).

6. The construction method of the compressed air energy storage bearing and sealing structure for shallow buried coal mine soft rock roadways as described in claim 2, characterized in that, Includes the following steps: After selecting the coal mine roadway to be used, firstly, anchor bolts (10) are installed, and then a layer of shotcrete is sprayed to smooth the surface of the surrounding rock inside the roadway; at the same time, the steel reinforcement frame is installed, the formwork is erected, and the second reinforced concrete lining layer (7) is poured. After the second reinforced concrete inner lining layer (7) is demolded, the third slip layer (6) is laid. The third slip layer (6) is required to be laid flat and smooth. Then the prefabricated second steel sealing layer (5) is erected. According to the above implementation steps, the second slip layer (4), the first reinforced concrete lining layer (3), the first slip layer (2) and the first steel sealing layer (1) are constructed in sequence; the construction of the compressed air storage bearing sealing structure for the soft rock roadway of the shallow buried coal mine is completed by repeating this process.

7. The construction method of the compressed air energy storage bearing and sealing structure for shallow buried coal mine soft rock roadways as described in claim 6, characterized in that, Based on the actual conditions of the tunnel, a waterproof coating is sprayed onto the surface of the first steel sealing layer (1) and the second steel sealing layer (5).

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