A method of sealing a compressed air reservoir in a coal roadway

Abstract

The present application relates to a kind of coal lane compressed air reservoir sealing method, comprising the following steps: high damage area of the arch foot periphery of roadway horse-shoe section two sides is grouted and reinforced;Lining is constructed in the inside of roadway, and the lining uses prestressed concrete lining or block type concrete lining;Air plug is constructed at the two ends of roadway;The underground water pressure at the depth of roadway is obtained, if the underground water pressure is less than set value, then grouting is formed in the periphery of roadway closed circle, and the area between closed circle and roadway is watered and pressurized, and the sealing method of the present application has low cost, and heat loss is small.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compressed air energy storage, in particular to a sealing method for compressed air storage in a coal roadway. BACKGROUND

[0002] The statements herein are provided only to complement the background of the present application and are not necessarily prior art.

[0003] At present, most coal roadways are constructed in limestones or sandstones with good engineering properties. It is of great significance and broad prospects to transform the abandoned coal roadways into compressed air storage. The transformation of the abandoned coal roadways into compressed air storage has geological particularity, and the transformation technology is still in its infancy, and there is less accumulation. The patent No. CN109356650A discloses a method for compressed air energy storage using underground coal mine roadway. The patent provides a method for compressed air energy storage using underground coal mine roadway, grouting reinforcement is performed on the surrounding rock loose circle, a reinforced concrete lining is constructed and a steel lining is made on the inner side of the lining, a steel barrier and an outer concrete barrier are arranged to seal the two ends of the roadway, and a flexible gas storage bag is placed in the roadway to store and call compressed air. The application has high technical innovation, but still has the following problems: first, the supporting form of this type of steel barrier and the inner surface steel lining layer of the lining has high thermal conductivity, resulting in large heat loss. Second, the main roadway is often constructed in limestones or sandstones with good engineering properties. The damage zone is fully reinforced, the safety factor is too high, and the engineering cost is extremely high. The contradiction between the applicability of the technology and the engineering cost is difficult to coordinate.

[0004] In summary, the structural sealing problem in the process of transforming the abandoned coal roadway into compressed air storage has not been well solved, and the existing technology still has not broken through the technical bottleneck of large-scale transformation and utilization of the abandoned coal roadway. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a sealing method for compressed air storage in a coal roadway, which has low transformation cost and small heat loss.

[0006] In order to achieve the above purpose, the present application is realized by the following technical scheme:

[0007] The embodiment of the present application provides a sealing method for compressed air storage in a coal roadway, comprising the following steps:

[0008] Grouting reinforcement is performed on the high damage zone around the arch foot on both sides of the horse-shoe shaped cross section of the roadway;

[0009] A lining is constructed inside the roadway, and the lining is a prestressed concrete lining or a block type concrete lining;

[0010] Air plugs are constructed at both ends of the roadway;

[0011] Obtaining the underground water pressure at the depth of the roadway, if the underground water pressure is less than a set value, grouting is carried out at the periphery of the roadway to form a closed ring, and water injection and pressurization are carried out in the area between the closed ring and the roadway.

[0012] Optionally, the outer edge of the cross section of the lining is a horseshoe shape matching the shape of the roadway, and the inner edge is a circular shape.

[0013] Optionally, the maximum thickness of the cross section of the lining at the position of the springing is 0.8m-1.2m.

[0014] Optionally, the inner diameter of the closed ring is 3-5 times the inner diameter of the lining, and the size of the closed ring along the longitudinal direction of the roadway is 1.1-1.4 times the length of the compressed air storage chamber of the roadway.

[0015] Optionally, the prestressed concrete lining adopts a ring anchor type prestressed lining or a grouting type prestressed lining.

[0016] Optionally, after the lining construction is completed, supplementary grouting is carried out between the lining and the roadway.

[0017] Optionally, when the prestressed concrete lining adopts a ring anchor type prestressed lining, the prestressed tendon adopts unbonded steel strand bundles.

[0018] Optionally, after the water injection and pressurization between the closed ring and the roadway are completed, a sealing layer is laid on the inner surface of the prestressed concrete lining.

[0019] Optionally, the sealing layer adopts a butyl rubber layer with a thickness of 10mm-20mm.

[0020] Optionally, the air plug adopts a concrete air plug, and the concrete air plug is in a cylindrical shape or a wedge shape or a sawtooth shape.

[0021] The beneficial effects of the present application are as follows:

[0022] 1. The compressed air storage sealing method of the present application only grouts and reinforces the springing of the horseshoe-shaped cross section of the roadway, and other areas are not treated, which still can ensure the stability of the roadway structure, thereby greatly saving the engineering cost.

[0023] 2. The compressed air storage sealing method of the present application forms a closed ring by grouting the periphery of the roadway when the underground water pressure at the depth of the roadway is less than a set value, and then carries out water injection and pressurization between the closed ring and the roadway, realizes the concept of combined sealing of high temperature and high pressure gas by using the lining and the water pressure outside the roadway, combines the actual situation that the roadway is built in limestone or sandstone in engineering practice, does not blindly reinforce the whole section, only reinforces a small range at the springing, reduces the disturbance to the surrounding rock, reduces the construction cost, and uses high pressure water for sealing, which has good sealing effect.

[0024] 3. In the compressed air storage tank sealing method of the present invention, the inner edge of the lining section is circular, which avoids stress concentration inside the storage tank, ensures that the lining structure is evenly compressed, reduces the adverse effects of tensile stress, and helps to improve the stability of the compressed air storage tank.

[0025] 4. The compressed air storage tank sealing method of the present invention adopts prestressed concrete lining or block concrete lining for lining, which reduces heat loss and does not produce cracks in the inflation and deflation states, thereby ensuring air tightness. At the same time, the sealing layer is eliminated inside the lining, and a combined sealing form inside and outside the tunnel is used, which greatly saves engineering costs and has stronger applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] Figure 1 This is a flow chart of the sealing method according to embodiment 1 of the present invention;

[0028] Figure 2 1 is a schematic cross-sectional view of a compressed air reservoir after sealing according to embodiment 1 of the present invention;

[0029] Figure 3 1 is a schematic longitudinal cross-sectional view of a sealed compressed air reservoir according to embodiment 1 of the present invention;

[0030] Figure 4 1 is a schematic cross-sectional view of a sealing ring according to embodiment 1 of the present invention;

[0031] Figure 5 1 is a schematic longitudinal cross-sectional view of a sealing ring according to embodiment 1 of the present invention;

[0032] Among them, 1. stratum surrounding rock, 2. disturbed area, 3. high damage area, 4. damaged reinforcement area, 5. compressed air storage chamber, 6. tunnel, 7. lining, 8. water pressure outside the surrounding rock, 9. air plug, 10. grouting pipe, 11. closed circle, 12. borehole, 13. water-rich rock area. DETAILED DESCRIPTION

[0033] Example 1

[0034] The embodiment of the present invention provides a method for sealing a coal lane compressed air storage tank, such as Figure 1-Figure 3 As shown, the following steps are included:

[0035] Step 1: Divide the excavation disturbance area of ​​the surrounding rock 1 into a high-damage area 3 and a disturbance area 2, and perform grouting reinforcement on the high-damage area 3 to prevent groundwater from seeping into the compressed air reservoir. The cross-section of the tunnel 6 in this embodiment is horseshoe-shaped, and the high-damage area is the rock area surrounding the arch foot of the horseshoe-shaped section.

[0036] Specifically, the damage zone is determined based on the distribution range of the plastic zone according to the stress analysis, and the range of the disturbance zone 2 is determined based on the drilling sonic method. Figure 1 As shown in the figure, due to the stress concentration effect, the high damage area 3 of the horseshoe section is concentrated at the arch feet on both sides of the original tunnel cross section 6. After grouting reinforcement and anti-seepage treatment are carried out in this area through the grouting pipe 10, a damaged reinforcement area 4 is formed, and the disturbance area 2 is not subjected to engineering reinforcement and anti-seepage treatment.

[0037] Since the coal roadway is set under geological conditions dominated by sandstone or limestone or interbedded layers of the two, research calculations show that not treating the disturbed zone 2 is sufficient to ensure the stability of the roadway structure under a cyclic load of 10MPa, thereby significantly saving engineering costs.

[0038] Step 2: constructing lining 7 inside the tunnel, wherein the lining 7 adopts prestressed concrete lining or block concrete lining.

[0039] In this embodiment, when the lining 7 adopts prestressed concrete lining, the lining adopts ring-anchor prestressed lining or grouting prestressed lining.

[0040] The ring-anchor prestressed lining establishes prestress by tensioning the prestressed tendons with tensioning machinery such as jacks, while the grouting prestressed lining uses high-pressure grouting to generate precompressive stress.

[0041] The above-mentioned prestressing forming method can adopt existing construction technology and will not be described in detail here.

[0042] By adopting prestressed concrete lining, no cracks will be generated during the inflation and deflation state, thus ensuring the air tightness of the overall structure.

[0043] Preferably, the lining 7 of this embodiment adopts a ring-anchor prestressed lining, the concrete adopts C40 concrete, and the prestressed tendons adopt high-strength, low-relaxation 1860-grade unbonded steel strand bundles. The unbonded steel strand bundles are arranged in two circles along the radial direction of the lining, and each circle has four strands arranged at equal intervals along the circumferential direction. The diameter of the prestressed tendons is 15.2 mm, the distance between the prestressed tendons and the inner surface of the lining is 0.5 m, and the distance between adjacent prestressed tendons is 0.5 m.

[0044] If the inner and outer edges of the lining 7 are both set to a horseshoe shape, the surrounding rock of the compressed air reservoir is prone to tension damage under the action of the high internal pressure gauge's inflation and deflation cycle, causing serious gas leakage and mine instability disasters. Therefore, in this embodiment, the outer edge of the cross section of the lining 7 is a horseshoe shape that matches the cross section of the tunnel 6, and the inner edge is circular, which avoids stress concentration inside the reservoir. Under inflation and deflation conditions, the lining structure is evenly stressed, and tensile stress is not easily generated inside, which is more conducive to structural durability.

[0045] The inner space of the lining is the compressed air storage chamber 5.

[0046] The outer rock mass at the two arch feet of the tunnel 6 is the high damage zone 3. Therefore, the size difference between the outer and inner sides of the lining 7 at the arch foot is the largest, that is, the thickness is the largest, and the maximum thickness is 0.8 meters to 1.2 meters. It is selected according to the actual operating pressure of the reservoir. When the maximum operating pressure of the compressed air reservoir is 10 MPa, the maximum thickness of the lining 7 at the arch foot is 0.8 meters. When the maximum operating pressure of the compressed air reservoir is 15 MPa, the maximum thickness of the lining 7 at the arch foot is 1.2 meters.

[0047] When using block-type concrete lining, the sealing performance of the lining structure depends on the cracks between adjacent blocks, and the sealing is ensured by the fillers between the cracks. The fillers can be made of existing polymer materials, such as acrylic adhesives and epoxy adhesives.

[0048] The lining 7 of this embodiment has the advantages of high strength, high toughness and low permeability. The permeability coefficient of the lining structure is less than 1X10 -20 m 2 Since no steel lining is used, it has better thermal insulation performance and reduces heat loss.

[0049] After the construction of lining 7 is completed, supplementary grouting is carried out between lining 7 and tunnel stratum surrounding rock 1 to fill the gap between lining 7 and stratum surrounding rock 1, so that the tunnel stratum surrounding rock 1 and lining 7 are tightly combined, and the grouting filling performance is evaluated by drilling sampling.

[0050] Step 3: Construct air plugs 9 at both ends of the tunnel to seal both ends of the tunnel 6.

[0051] The air plug 9 is a concrete air plug. The concrete used is the same as the concrete used in the lining construction. The construction method of the air plug can adopt the existing method and will not be described in detail here.

[0052] The shape of the concrete air lock is cylindrical, wedge-shaped or sawtooth-shaped, and those skilled in the art can configure it according to actual needs.

[0053] The wedge shape refers to the shape of a concrete air plug with a larger area at one end and a smaller area at the other end, and the sawtooth shape refers to the shape of a concrete air plug with a cylindrical structure and multiple protrusions on the cylindrical surface.

[0054] Step 4: Calculate the groundwater pressure of the surrounding strata at the depth of the current tunnel compressed air storage chamber 5 according to the hydrogeological conditions and the groundwater level. When the calculated groundwater pressure is not less than the set value, it is determined that the water curtain of the surrounding strata can be used to seal the compressed air storage chamber.

[0055] In this embodiment, the underground water pressure is calculated based on the buried depth of the compressed air storage chamber 5. The water pressure at a tunnel buried depth of 100 meters is considered to be 1 MPa, so the set value is 1 MPa.

[0056] like Figure 4-Figure 5 As shown, when the calculated groundwater pressure is less than the set value, holes are drilled in the lining and the surrounding rock mass to form boreholes 12, and a full-section closed ring 11 is formed on the periphery of the tunnel by grouting using the boreholes 12. The inner diameter of the closed ring 11 is 3-5 times the inner diameter of the inner circle of the lining, and the dimension of the closed ring 11 along the length direction of the tunnel 6 is 1.1 times to 1.4 times the length of the compressed air storage chamber, ensuring that the closed ring 11 can wrap the air plug and the compressed air storage.

[0057] The thickness of the sealing ring can be set according to the water injection pressure and will not be described in detail here.

[0058] Water is injected and pressurized in the rock area between the tunnel 6 and the closed circle 11 through the drilling hole 12 to form a water-rich rock area 13, and a sealed water curtain is formed outside the lining. The water injection pressure can be set according to the actual working conditions and will not be described in detail here.

[0059] After the water injection and pressurization are completed, a sealing layer is laid on the inner surface of the lining. In this embodiment, the sealing layer adopts a butyl rubber layer to further improve the sealing effect of the lining. The thickness of the butyl rubber layer is 10mm-20mm, and those skilled in the art can set it according to actual needs.

[0060] In each cycle of inflation and deflation, the high-temperature and high-pressure gas is sealed by relying on the lining, the air plug and the water pressure of the surrounding rock. Taking into account the actual situation that the tunnel is built in limestone or sandstone in actual engineering, instead of blindly reinforcing the entire section, only a small range of reinforcement is carried out on the arch foot, which reduces the disturbance to the surrounding rock and reduces the construction cost. In addition, the sealing effect is good by using high-pressure water.

[0061] As the compressed air storage service life increases, even if the sealing performance of the lining decreases, after the high-pressure gas breaks through the lining and the surrounding rock formation with good physical and mechanical properties, the water pressure outside the surrounding rock can minimize gas leakage, meeting the engineering requirement of less than 1% daily gas leakage in the storage tank.

[0062] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for sealing a compressed air storage tank in a coal lane, characterized in that: The following steps are involved: Grouting reinforcement is performed on the high-damage areas around the arch feet on both sides of the horseshoe-shaped section of the roadway, and other areas are not treated; Constructing lining inside the tunnel, wherein the lining adopts prestressed concrete lining or segmented concrete lining; Construct air plugs at both ends of the tunnel; Obtain the groundwater pressure at the depth of the tunnel. If the groundwater pressure is less than the set value, grouting is performed on the periphery of the tunnel to form a closed ring, and water injection is performed to increase the pressure in the area between the closed ring and the tunnel.

2. A method for sealing a coal lane compressed air storage tank according to claim 1, characterized in that: The outer edge of the cross section of the lining is a horseshoe shape that matches the shape of the tunnel, and the inner edge is a circle.

3. A method for sealing a coal lane compressed air storage tank according to claim 2, characterized in that: The maximum thickness of the lining cross section at the arch foot is 0.8m-1.2m.

4. A method for sealing a coal lane compressed air storage tank according to claim 2, characterized in that: The inner diameter of the closed ring is 3-5 times the inner diameter of the lining, and the longitudinal dimension of the closed ring along the tunnel is 1.1-1.4 times the length of the tunnel compressed air storage chamber.

5. The method for sealing a coal lane compressed air storage tank according to claim 1, wherein: The prestressed concrete lining adopts a ring-anchor prestressed lining or a grouting prestressed lining.

6. A method for sealing a coal lane compressed air storage tank according to claim 1, characterized in that: After the lining construction is completed, additional grouting is carried out between the lining and the tunnel.

7. A method for sealing a coal lane compressed air storage tank according to claim 5, characterized in that: When the prestressed concrete lining adopts the ring-anchor prestressed lining, the prestressed tendons adopt unbonded steel strand bundles.

8. The method for sealing a coal lane compressed air storage tank according to claim 1, characterized in that: After water injection and pressurization between the closed ring and the tunnel are completed, a sealing layer is laid on the inner surface of the prestressed concrete lining.

9. A method for sealing a coal lane compressed air storage tank according to claim 8, characterized in that: The sealing layer is a butyl rubber layer with a thickness of 10mm-20mm.

10. The method for sealing a coal lane compressed air storage tank according to claim 1, characterized in that: The air plug is a concrete air plug, which is cylindrical, wedge-shaped or sawtooth-shaped.

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