High-pressure tunnel sealing method and sealing structure using confining pressure

Abstract

The invention belongs to the technical field of high-pressure tunnel sealing, and particularly discloses a high-pressure tunnel sealing method and sealing structure utilizing confining pressure, and the sealing method comprises the steps that the horizontal maximum principal stress direction of the area where a to-be-built high-pressure tunnel is located is determined; the axis of the high-pressure tunnel to be built is determined according to the horizontal maximum principal stress direction; gradually excavating along the axis by using a shield construction method, and mounting a rigid sealing layer on a contour formed in the excavation process; the rigid sealing layer is composed of a plurality of prefabricated rigid sealing pieces. And after excavation is completed, a flexible sealing layer is arranged on the rigid sealing layer. According to the method, the axis of the high-pressure tunnel is determined according to the horizontal maximum principal stress direction, so that the available crustal stress is maximum; a shield construction method is used for retaining ground stress, and a rigid sealing layer and a flexible sealing layer are used for sealing, so that the sealing performance of the high-pressure tunnel is guaranteed. The shield construction method is used for construction, and the construction progress is high; and the design and construction difficulty is reduced by utilizing ground stress, and the engineering cost is low.

Description

Technical Field

[0001] The invention discloses a high-pressure tunnel sealing method and a sealing structure using confining pressure, belonging to the technical field of high-pressure tunnel sealing. Background Art

[0002] The pressure (air pressure / water pressure) in underground gas storage facilities such as artificial caves and abandoned mines of compressed gas energy storage power stations, as well as high-pressure water diversion tunnels of pumped storage power stations, is usually as high as 10MPa or more, and has a long service life. At present, this type of high-pressure tunnel is mainly excavated by drilling and blasting and sealed with thick steel plates, but the construction progress is slow and the project cost is high, which to a certain extent limits the approval of the project. Furthermore, the high-pressure tunnel is located underground, and its ground stress is a favorable load for the tunnel under the action of internal pressure. After excavation by traditional drilling and blasting, the ground stress is quickly released and cannot be utilized, resulting in a large internal pressure borne by the sealing structure, which is not conducive to ensuring the sealing of the cavity in the tunnel. Summary of the invention

[0003] The purpose of the present invention is to provide a high-pressure tunnel sealing method and sealing structure using confining pressure, so as to solve the technical problems in the prior art that high-pressure tunnels are mainly excavated by drilling and blasting method and sealed by using thick steel plates, resulting in slow construction progress and high engineering cost, and the drilling and blasting method excavation will lead to the rapid release of the load beneficial to the high-pressure tunnel - ground stress, which is not conducive to the sealing of the high-pressure tunnel.

[0004] A first aspect of the present invention provides a high-pressure tunnel sealing method using confining pressure, comprising: Step 1, determining the direction of the maximum horizontal principal stress in the area where the high-pressure tunnel to be built is located; Step 2: determining the axis of the high-pressure tunnel to be built according to the direction of the maximum horizontal principal stress; Step 3, gradually excavating along the axis using a shield construction method, and installing a rigid sealing layer on the contour formed during the excavation process; the rigid sealing layer is composed of a plurality of prefabricated rigid sealing members; Step 4: After excavation is completed, a flexible sealing layer is provided on the rigid sealing layer.

[0005] Preferably, the angle between the axis of the high-pressure tunnel to be built and the direction of the horizontal maximum principal stress is 75°~90°.

[0006] A second aspect of the present invention provides a high-pressure tunnel sealing structure using confining pressure, which is constructed using the above-mentioned high-pressure tunnel sealing method using confining pressure, and the sealing structure includes a rigid sealing layer and a flexible sealing layer; The rigid sealing layer is arranged on the profile formed by the shield construction method, and the rigid sealing layer comprises a plurality of prefabricated rigid sealing members; The flexible sealing layer is arranged on a side surface of the rigid sealing layer away from the contour.

[0007] Preferably, each prefabricated rigid seal comprises a prefabricated concrete block and a steel plate; The precast concrete block is fixedly connected to the profile; The steel plate is fixedly arranged on a side surface of the precast concrete block away from the contour through a fixing piece.

[0008] Preferably, the thickness of the precast concrete block is greater than or equal to 40 cm; The thickness of the steel plate is less than or equal to 1 cm.

[0009] Preferably, the fixing member is a bolt or a welded rib pre-embedded in the precast concrete block.

[0010] Preferably, the edge of the steel plate is beveled, and the angle of the bevel is 20° to 45°.

[0011] Preferably, the construction joint between adjacent precast concrete blocks is less than or equal to 2 mm.

[0012] Preferably, a protrusion is provided at the flexible sealing layer corresponding to the position of the construction joint between adjacent precast concrete blocks.

[0013] Preferably, the flexible sealing layer is made of butyl rubber, acrylate or polyurea.

[0014] Compared with the prior art, the high-pressure tunnel sealing method and sealing structure using confining pressure of the present invention have the following beneficial effects: The present invention determines the axis of the high-pressure tunnel according to the direction of the maximum horizontal principal stress, so that the available ground stress is maximized, further uses the shield construction method to retain the ground stress, and uses a rigid sealing layer and a flexible sealing layer to seal the high-pressure tunnel, thereby ensuring the sealing performance of the high-pressure tunnel. While taking advantage of the fast progress of shield construction, the present invention reduces construction interference, utilizes the surrounding rock pressure, and thus reduces the difficulty of design and construction, is conducive to the design of the sealing structure in the tunnel, and has a low engineering cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of a high-pressure tunnel sealing structure using confining pressure according to an embodiment of the present invention.

[0016] Figure 2 Schematic diagram of a prefabricated rigid seal in an embodiment of the present invention.

[0017] Figure 3 It is a schematic structural diagram of a construction joint between adjacent precast concrete blocks in an embodiment of the present invention.

[0018] In the figure: 1. surrounding rock; 2. precast concrete block; 3. cavity inside the cave; 4. construction joint; 5. steel plate; 6. flexible sealing layer. DETAILED DESCRIPTION

[0019] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0020] The first aspect of the embodiment of the present invention provides a high-pressure tunnel sealing method using confining pressure. The high-pressure tunnel is located underground, and its ground stress is a favorable load for the tunnel under the action of internal pressure. However, the ground stress is quickly released after excavation by the traditional drilling and blasting method, and it cannot be utilized. The high-pressure tunnel sealing method of the present invention can effectively utilize the ground stress, thereby reducing the internal pressure effect value, and then improving the sealing performance of the high-pressure tunnel. The ground stress is mainly characterized by the confining pressure.

[0021] The high-pressure tunnel sealing method using confining pressure according to an embodiment of the present invention comprises: Step 1: Determine the direction of the maximum horizontal principal stress in the area where the high-pressure tunnel to be built is located.

[0022] Step 2: Determine the axis of the high-pressure tunnel to be built according to the direction of the maximum horizontal principal stress.

[0023] Step 3: gradually excavate along the axis using a shield construction method, and install a rigid sealing layer on the contour formed during the excavation process; wherein the rigid sealing layer is composed of a plurality of prefabricated rigid sealing components.

[0024] For example, the shield machine excavates the rock mass through the cutter head, and the rigid sealing layer is installed immediately after the excavation contour is formed, so as to retain the ground stress effect (i.e., retain the confining pressure) as much as possible, and the excavated material is transported out through the conveyor belt. According to this method, the continuous excavation ends directly, and a high-pressure tunnel with a rigid sealing layer is obtained, and the rock mass outside the high-pressure tunnel is the surrounding rock 1.

[0025] The present invention utilizes the shield construction method to reduce the impact of rock excavation disturbance, retains the ground stress to act on the high-pressure tunnel, and thus can reduce the internal pressure effect value; for example, the measured minimum principal stress at the tunnel location is 5MPa, and the ground stress disturbed by shield excavation is reduced to 4MPa. Under the action of the internal pressure of 10MPa, the actual internal pressure after the superposition of the two is only 6MPa, which greatly reduces the internal pressure effect value and makes it easier to ensure the sealing of the cavity 3 in the tunnel.

[0026] Step 4: After excavation is completed, a flexible sealing layer 6 is provided on the rigid sealing layer.

[0027] In order to further ensure the sealing performance, the present invention adopts a solution of laying a layer of flexible sealing material all over the rigid sealing layer in the complete high-pressure tunnel to prepare the flexible sealing layer 6, thereby ensuring the overall sealing performance in the tunnel.

[0028] During conventional drilling and blasting construction, the tunnel axis is required to form a small angle with the direction of the maximum horizontal principal stress, thereby ensuring the stability of the surrounding rock 1 during drilling and blasting construction. In order to make fuller use of the ground stress effect and transform unfavorable conditions into favorable conditions, the present invention limits the angle between the axis of the high-pressure tunnel to be built and the direction of the maximum horizontal principal stress to 75°~90°, which is a large angle, and combines the shield construction method for construction, thereby ensuring the stability of the surrounding rock 1 while making full use of the ground stress.

[0029] A second aspect of an embodiment of the present invention provides a high-pressure tunnel sealing structure using confining pressure, such as Figures 1 to 3 As shown, the high-pressure tunnel sealing method using confining pressure is used for construction, and the sealing structure includes a rigid sealing layer and a flexible sealing layer 6. The rigid sealing layer is arranged on the contour formed by the shield construction method, and the rigid sealing layer includes a plurality of prefabricated rigid sealing parts; the flexible sealing layer 6 is arranged on the surface of the rigid sealing layer away from the contour.

[0030] The rigid sealing layer in the present invention has a bearing function while performing a sealing function. To improve its sealing performance and bearing capacity, each prefabricated rigid sealing member in the embodiment of the present invention includes a prefabricated concrete block 2 and a steel plate 5; the prefabricated concrete block 2 is fixedly connected to the profile; and the steel plate 5 is fixedly arranged on the side surface of the prefabricated concrete block 2 away from the profile through a fixing member.

[0031] In the embodiment of the present invention, a thin steel plate is arranged on the precast concrete block 2 to ensure its single body sealing performance, mainly to solve the problem of crack leakage inside the precast concrete block 2; after the construction of the precast concrete block 2 is completed, a flexible sealing layer 6 is arranged as a whole inside the cavern to ensure the overall sealing performance of the cavern, mainly to solve the problem of air leakage in the construction joints 4 between the precast concrete blocks 2.

[0032] The thickness of the precast concrete block 2 in the embodiment of the present invention is greater than or equal to 40 cm, thereby ensuring its rigidity; the thickness of the steel plate 5 is less than or equal to 1 cm, and the use of a thin steel plate can ensure the sealing performance of the precast concrete block 2 under high internal pressure.

[0033] The fixing members for fixing the steel plate 5 in the embodiment of the present invention may specifically be bolts or welded ribs embedded in the precast concrete block 2, that is, fixation can be achieved by bolts or welding, with good stability and easy operation.

[0034] In order to prevent the flexible sealing layer 6 from being pressed into the construction joint 4 between multiple prefabricated rigid seals under the high-pressure tunnel internal pressure and causing damage, the embodiment of the present invention limits the construction joint 4 between adjacent prefabricated concrete blocks 2 to be less than or equal to 2 mm, and the edge of the steel plate 5 is beveled, and the angle of the bevel is 20°~45°. The embodiment of the present invention reduces the possibility of the flexible sealing layer 6 being pressed in by limiting the construction joint 4 to be less than or equal to 2 mm. Furthermore, by limiting the edge of the steel plate 5 to use a bevel, the interface between the flexible sealing layer 6 and the prefabricated rigid seal at the construction joint 4 is a plane, rather than a high gap, thereby reducing the possibility of the flexible sealing layer 6 being pressed into the construction joint 4, and once pressed in, the probability of its damage can also be reduced.

[0035] In order to further reduce the damage probability of the flexible sealing layer 6, the embodiment of the present invention provides a protrusion on the flexible sealing layer 6 corresponding to the position of the construction joint 4 between adjacent precast concrete blocks 2, thereby leaving a margin for pressing in, reducing the damage probability and ensuring the sealing of the high-pressure tunnel.

[0036] The embodiment of the present invention sets bevel angles on the edges of the steel plate 5 and sets corresponding protrusions on the flexible sealing layer 6, so that the pressure can be effectively transmitted to the precast concrete block 2, avoiding the flexible sealing layer 6 from being pressed into the construction joint 4 and causing failure and damage, thereby causing serious leakage in the cavern.

[0037] The material of the flexible sealing layer 6 of the embodiment of the present invention is butyl rubber, acrylate or polyurea. The above materials have the advantages of good flexibility, good air tightness, heat resistance, aging resistance, etc., so the sealing of the high-pressure tunnel can be guaranteed.

[0038] The present invention determines the axis of the high-pressure tunnel according to the direction of the maximum horizontal principal stress, so that the available ground stress is maximized, further uses the shield construction method to retain the ground stress, and uses a rigid sealing layer and a flexible sealing layer 6 to seal the high-pressure tunnel, thereby ensuring the sealing performance of the high-pressure tunnel.

[0039] The present invention takes advantage of the fast progress of shield construction while reducing construction interference, utilizing the pressure of the surrounding rock 1, thereby reducing the difficulty of design and construction, being beneficial to the design of the sealing structure in the tunnel, and thereby reducing the project cost.

[0040] The above are only several embodiments of the present invention and are not intended to limit the present invention in any form. Although the present invention is disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, using the above disclosed technical content to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A high-pressure tunnel sealing method using confining pressure, characterized in that: include: Step 1, determining the direction of the maximum horizontal principal stress in the area where the high-pressure tunnel to be built is located; Step 2: determining the axis of the high-pressure tunnel to be built according to the direction of the maximum horizontal principal stress; Step 3, gradually excavating along the axis using a shield construction method, and installing a rigid sealing layer on the contour formed during the excavation process; the rigid sealing layer is composed of a plurality of prefabricated rigid sealing members; Step 4: After excavation is completed, a flexible sealing layer is provided on the rigid sealing layer.

2. The high-pressure tunnel sealing method using confining pressure according to claim 1, characterized in that: The angle between the axis of the high-pressure tunnel to be built and the direction of the horizontal maximum principal stress is 75°~90°.

3. A high-pressure tunnel sealing structure using confining pressure, characterized in that: The construction is carried out using the high-pressure tunnel sealing method using confining pressure as described in claim 1 or 2, wherein the sealing structure comprises a rigid sealing layer and a flexible sealing layer; The rigid sealing layer is arranged on the profile formed by the shield construction method, and the rigid sealing layer comprises a plurality of prefabricated rigid sealing members; The flexible sealing layer is arranged on a side surface of the rigid sealing layer away from the contour.

4. The high-pressure tunnel sealing structure using confining pressure according to claim 3 is characterized in that: Each precast rigid seal comprises a precast concrete block and a steel plate; The precast concrete block is fixedly connected to the profile; The steel plate is fixedly arranged on a side surface of the precast concrete block away from the contour through a fixing piece.

5. The high-pressure tunnel sealing structure using confining pressure according to claim 4, characterized in that: The thickness of the precast concrete block is greater than or equal to 40 cm; The thickness of the steel plate is less than or equal to 1 cm.

6. The high-pressure tunnel sealing structure using confining pressure according to claim 4, characterized in that: The fixing members are bolts or welding ribs embedded in the precast concrete blocks.

7. The high-pressure tunnel sealing structure using confining pressure according to claim 4, characterized in that: The edge of the steel plate is beveled, and the angle of the bevel is 20° to 45°.

8. The high-pressure tunnel sealing structure using confining pressure according to claim 7, characterized in that: The construction joint between adjacent precast concrete blocks is less than or equal to 2mm.

9. The high-pressure tunnel sealing structure using confining pressure according to claim 7 or 8, characterized in that: The flexible sealing layer is provided with protrusions at locations corresponding to construction joints between adjacent precast concrete blocks.

10. The high-pressure tunnel sealing structure using confining pressure according to claim 3, characterized in that: The material of the flexible sealing layer is butyl rubber, acrylate or polyurea.

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