Method for protecting tunnel in dissolving cavity

Abstract

The invention provides a method for protecting a tunnel in a cavern, which belongs to the technical field of tunnel construction and comprises the following steps of: arranging an arch frame on the outer periphery of the tunnel in the cavern, and hanging a baffle net on the outer side of the arch frame; an outer formwork is arranged on the outer side of the blocking net around the outside of the arch frame, an inner formwork is arranged on the inner side of the arch frame, and a concrete spraying space is formed between the outer formwork and the inner formwork; concrete spraying construction is conducted on the concrete spraying space, so that the concrete forms a dense layer between the arch frame and the outer formwork, and the sprayed and rebounded concrete forms a loose layer between the arch frame and the inner formwork; and the dense layer, the blocking net, the arch frame and the unconsolidated layer serve as protective layers of the tunnel in the cavern, and the tunnel in the cavern is protected through the protective layers. The problems that in the prior art, the tunnel in the dissolving cavity mostly adopts a rigid structure protection mode, the phenomena of lining concrete cracking, waterproof plate tearing and the like are prone to occurring when the tunnel bears falling stone impact, and consequently the service life of the tunnel is shortened or water leakage occurs can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel construction, and more specifically, to a method for protecting a tunnel in a dissolution cavity. Background Art

[0002] At present, when a tunnel passes through a large karst cave or fault, the karst cavity cannot be backfilled due to construction conditions or groundwater system restrictions. In order to ensure the safety of the tunnel, enhanced support is often used.

[0003] Tunnel support is generally divided into: primary support (steel arch + steel mesh + shotcrete) and (reinforced) concrete secondary lining. Both types of protection are rigid structures. When subjected to the impact of falling rocks, they are prone to problems such as cracking of the lining concrete and tearing of the waterproof board, which can shorten the operating life of the tunnel or cause problems such as water leakage. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a method for protecting tunnels in dissolution cavities, so as to solve the problem that in the prior art, tunnels in dissolution cavities mostly adopt a rigid structure protection method, which is prone to cracking of lining concrete and tearing of waterproof boards when subjected to the impact of falling rocks, thereby shortening the operating life of the tunnel or causing water leakage.

[0005] The present invention provides a method for protecting a tunnel in a dissolution cavity, comprising the following steps:

[0006] An arch frame is arranged around the outer periphery of the tunnel in the dissolution cavity, and a retaining net is hung on the outer side of the arch frame;

[0007] An outer template is arranged on the outside of the retaining net around the outside of the arch frame, and an inner template is arranged on the inside of the arch frame, so that a concrete spraying space is formed between the outer template and the inner template;

[0008] Performing concrete spraying construction in the concrete spraying space, so that the concrete forms a dense layer between the arch frame and the outer formwork, and the sprayed and rebounded concrete forms a loose layer between the arch frame and the inner formwork;

[0009] The dense layer, the retaining net, the arch frame and the loose layer are used as protective layers of the tunnel in the dissolution cavity, and the main structure of the tunnel in the dissolution cavity is protected by the protective layers.

[0010] In addition, a preferred solution is that an arch frame is arranged around the outer periphery of the tunnel in the dissolution cavity, and a retaining net is hung on the outer side of the arch frame, including:

[0011] Determining the size of the arch frame according to the preset thickness of the protective layer and the excavation contour line of the tunnel in the solution cavity;

[0012] Determine the number of arches provided around the tunnel in the dissolution cavity and the position of each arch according to the length of the tunnel in the dissolution cavity and the size of the arch;

[0013] According to the number of the arches and the position of each arch, arches are arranged outside the tunnel in the dissolution cavity, and the retaining net is hung outside the enclosed arches and between adjacent arches.

[0014] In addition, a preferred solution is that when the arch feet on both sides of the arch frame are installed on the plate structure or beam structure of the tunnel in the dissolution cavity that crosses the underground river or crack, the arch frame is an I-beam arch frame or a steel grating arch frame of models I12 to I14.

[0015] In addition, a preferred solution is that when the arch feet on both sides of the arch frame are installed on the bedrock of the tunnel in the dissolution cavity, the arch frame is an I-beam arch frame of model I18 or above.

[0016] In addition, a preferred solution is that the retaining net is a steel mesh.

[0017] In addition, a preferred solution is to set an outer template around the outside of the arch frame on the outside of the retaining net, and in the process of laying out the inner template on the inside of the arch frame, the distance between the arch frame and the outer template is 3-5 cm.

[0018] In addition, a preferred solution is that during the process of performing concrete spraying construction into the concrete spraying space, the landing point of the concrete spraying is made on the outer formwork, and the rebound concrete is concentrated between the outer formwork and the inner formwork.

[0019] In addition, a preferred solution is that, during the process of performing concrete spraying construction into the concrete spraying space, the concrete spraying method is dry spraying or wet spraying.

[0020] In addition, it is preferred that, during the process of spraying concrete into the concrete spraying space, the concrete rebound rate is at least 50%.

[0021] In addition, a preferred solution is that when the thickness of the protective layer is less than or equal to 1m, the construction method of the protective layer is single-layer construction; when the thickness of the protective layer is greater than 1m, the construction method of the protective layer is at least two-layer construction.

[0022] It can be seen from the above technical scheme that the method for protecting a tunnel in a karst cavity provided by the present invention is to set an arch frame around the outer periphery of the tunnel in the karst cavity, hang a retaining net on the outer side of the arch frame, set an outer formwork around the outer side of the arch frame on the outer side of the retaining net, arrange an inner formwork on the inner side of the arch frame, and construct shotcrete between the outer formwork and the inner formwork. During the concrete shotcrete construction process, the concrete forms a dense layer between the arch frame and the outer formwork, and the sprayed and rebounded concrete forms a loose layer between the arch frame and the inner formwork, and finally a protective layer composed of a dense layer, a retaining net, an arch frame and a loose layer is obtained. The protective layer is a structure with a dense outer side and a loose inner side formed with the arch frame as the boundary. The dense layer, the retaining net and the arch frame together form a solid outer layer of tunnel protection to withstand the impact of falling rocks. The inner loose layer is used to buffer the impact force of falling rocks, thereby protecting the tunnel support from being damaged, extending the service life of the tunnel in the karst cavity, and reducing diseases.

[0023] In order to achieve the above and related purposes, one or more aspects of the present invention include the features that will be described in detail later. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] By referring to the following description in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more clear and easy to understand. In the accompanying drawings:

[0025] Figure 1 is a flow chart of a method for protecting a tunnel in a dissolution cavity according to an embodiment of the present invention;

[0026] Figure 2 is a schematic diagram of the interface structure of a protective layer according to an embodiment of the present invention;

[0027] Figure 3 for Figure 2 Magnified view of part A.

[0028] In the attached drawings, 1-tunnel in the cavity, 2-arch frame, 21-arch foot, 3-blocking net, 4-external formwork, 5-inner formwork, 6-dense layer, 7-loose layer, 8-support plate, 9-underground river, 10-cavity.

[0029] The same reference numerals throughout the drawings indicate similar or corresponding features or functions. DETAILED DESCRIPTION

[0030] In the following description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. However, it is apparent that these embodiments may also be implemented without these specific details.

[0031] In view of the above-mentioned prior art, tunnels in dissolution cavities are mostly protected by rigid structures, which are prone to cracking of lining concrete and tearing of waterproof panels when subjected to the impact of falling rocks, thereby shortening the operating life of the tunnel or causing problems such as water leakage. A method for protecting tunnels in dissolution cavities is proposed.

[0032] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0033] In order to illustrate the tunnel protection method in the dissolution cavity provided by the present invention, Figure 1 The process of the tunnel protection method in the dissolution cavity according to an embodiment of the present invention is shown; Figure 2 The interface structure of the protective layer according to an embodiment of the present invention is shown; Figure 3 Shows Figure 2 A magnified structure of part A.

[0034] like Figures 1 to 3 As shown together, the method for protecting a tunnel in a dissolution cavity provided by the present invention comprises the following steps:

[0035] Step S1, an arch frame 2 is arranged around the outer periphery of the tunnel 1 in the dissolution cavity, and a retaining net 3 is hung on the outer side of the arch frame 2;

[0036] Step S2, setting an outer template 4 around the outside of the arch frame 2 on the outside of the retaining net 3, and laying an inner template 5 on the inside of the arch frame 2, so that a concrete spraying space is formed between the outer template 4 and the inner template 5;

[0037] Step S3, spraying concrete into the concrete spraying space, so that the concrete forms a dense layer 6 between the arch frame 2 and the outer formwork 4, and the sprayed and rebounded concrete forms a loose layer 7 between the arch frame 2 and the inner formwork 5;

[0038] Step S4, using the dense layer 6, the retaining net 3, the arch frame 2 and the loose layer 7 as a protective layer for the tunnel 1 in the dissolution cavity, and protecting the main structure of the tunnel 1 in the dissolution cavity through the protective layer.

[0039] The method for protecting a tunnel in a karst cavity provided by the present invention is particularly suitable for preventing rocks falling from the top of the karst cavity from damaging the main structure of the tunnel when the tunnel passes through a fault or a large karst cave, thereby playing a role in strengthening the support of the tunnel in the cavity.

[0040] An arch frame 2 is arranged around the outer periphery of the tunnel 1 in the cavity, and a retaining net 3 is hung on the outer side of the arch frame 2, an outer formwork 4 is arranged around the outer side of the arch frame 2 on the outer side of the retaining net 3, an inner formwork 5 is arranged on the inner side of the arch frame 2, and shotcrete is constructed between the outer formwork 4 and the inner formwork 5. During the concrete shotcreting construction process, the concrete forms a dense layer 6 between the arch frame 2 and the outer formwork 4, and the sprayed and rebounded concrete forms a loose layer 7 between the arch frame 2 and the inner formwork 5, and finally a protective layer composed of the dense layer 6, the retaining net 3, the arch frame 2 and the loose layer 7 is obtained. The protective layer is a structure with a dense outer side and a loose inner side formed with the arch frame 2 as the boundary. The dense layer 6, the retaining net 3 and the arch frame 2 together form a solid outer layer of tunnel protection to withstand the impact of falling rocks. The inner loose layer 7 is used to buffer the impact force of falling rocks, thereby protecting the tunnel support from being destroyed, extending the service life of the tunnel in the cavity, and reducing diseases.

[0041] As a preferred solution of the present invention, an arch frame 2 is arranged around the outer periphery of the tunnel 1 in the dissolution cavity, and a retaining net 3 is hung outside the arch frame 2, including:

[0042] Determine the size of the arch 2 according to the preset thickness of the protective layer and the excavation contour of the tunnel 1 in the solution cavity;

[0043] According to the length of the tunnel 1 in the dissolution cavity and the size of the arch 2, the number of arches arranged around the tunnel 1 in the dissolution cavity and the position of each arch are determined;

[0044] According to the number of arches and the position of each arch, arches 2 are arranged outside the tunnel 1 in the dissolution cavity, and retaining nets 3 are hung outside the arches 2 and between adjacent arches 2 .

[0045] Specifically, one or more arches 2 are arranged along the length extension direction of the tunnel 1 in the cavity. The number of arches 2 is related to the length of the tunnel 1 in the cavity and the size of a single arch 2, and can be calculated according to the actual situation. Therefore, it is necessary to first determine the size of the arch 2 according to the preset thickness of the protective layer and the excavation contour line of the tunnel 1 in the cavity. Among them, the preset thickness of the protective layer can be comprehensively determined based on the size of the fallen rocks on the top of the tunnel 1 in the cavity and the height of the cavity 1. The excavation contour line of the tunnel 1 in the cavity is determined according to the tunnel construction requirements. After determining the size of the arch 2, the number of arches 2 and the position of each arch 2 are determined, and then the processed arch 2 is enclosed outside the tunnel 1 in the cavity, and a retaining net 3 is hung on the outside of the enclosed arch 2 and between adjacent arches 2.

[0046] As a preferred embodiment of the present invention, when the arch feet 21 on both sides of the arch frame 2 are installed on the plate structure or beam structure of the tunnel 1 in the dissolution cavity that crosses the underground river or crack, the arch frame 2 is an I-beam arch frame or a steel grid arch frame of model I12 to I14.

[0047] Specifically, Figure 2As shown, when the arch feet 21 on both sides of the arch frame 2 are installed on the support plate 8 across the underground river 9 of the tunnel 1 in the dissolution cavity, the arch foot 21 has a small bearing capacity. In order to avoid excessive penetration and multiple impacts on the support plate 8, the arch frame 2 preferably adopts a small I-beam arch frame or a steel grid arch frame. Among them, the small I-beam arch frame is preferably, but not limited to, an I-beam arch frame of models I12 to I14.

[0048] As a preferred solution of the present invention, when the arch feet 21 on both sides of the arch frame 2 are installed on the bedrock of the tunnel 1 in the dissolution cavity, the arch frame 21 is an I-beam arch frame of model I18 or above.

[0049] Specifically, when the arch feet 21 on both sides of the arch frame 2 are installed on the bedrock of the tunnel 1 in the cavity, the arch feet 21 have a large bearing capacity, so the arch frame 21 can use a large I-beam, preferably an I-beam arch frame of model I18 or above.

[0050] As a preferred solution of the present invention, the retaining net 3 is a steel mesh.

[0051] Specifically, the retaining net 3 plays a role in receiving falling rocks, and preferably, but not limited to, a steel mesh with good receiving capacity is used.

[0052] As a preferred solution of the present invention, an outer template is arranged on the outside of the retaining net around the outside of the arch frame. During the process of arranging the inner template on the inner side of the arch frame, the distance between the arch frame 2 and the outer template 4 is 3-5 cm.

[0053] Specifically, the distance between the arch frame 2 and the outer formwork 4 is preferably 3-5 cm, and a solid protective layer is formed after spraying concrete. The specific distance can be determined according to actual conditions.

[0054] As a preferred solution of the present invention, during the process of concrete spraying construction into the concrete spraying space, the landing point of the concrete spraying is made on the outer formwork 4, and the rebound concrete is concentrated between the outer formwork 4 and the inner formwork 5.

[0055] Specifically, the sprayed concrete falls on the outer formwork 4, and the rebound concrete is concentrated between the outer formwork 4 and the inner formwork 5 to form a protective layer that is dense on the outside and loose on the inside.

[0056] As a preferred solution of the present invention, during the process of performing concrete spraying construction into the concrete spraying space, the concrete spraying method is dry spraying or wet spraying.

[0057] It should be noted that the shotcrete can be sprayed by dry spraying or wet spraying, and the present invention does not make any special limitation on this.

[0058] As a preferred solution of the present invention, during the process of spraying concrete into the concrete spraying space, the concrete rebound rate is at least 50%.

[0059] As a preferred solution of the present invention, when the thickness of the protective layer is less than or equal to 1m, the construction method of the protective layer is single-layer construction; when the thickness of the protective layer is greater than 1m, the construction method of the protective layer is at least two-layer construction.

[0060] Specifically, the thickness of the protective layer is determined according to the impact force of falling rocks. When the thickness of the protective layer is greater than 1m, the protective layer can be divided into double-layer or multi-layer construction. The thickness of each single-layer protective layer should not be too large. It can be set according to actual needs, and the present invention does not make any special limitation on this.

[0061] It can be seen from the above specific embodiments that the method for protecting a tunnel in a solution cavity provided by the present invention is to set an arch frame around the outer periphery of the tunnel in the solution cavity, hang a retaining net on the outer side of the arch frame, set an outer formwork around the outer side of the arch frame on the outer side of the retaining net, arrange an inner formwork on the inner side of the arch frame, and construct shotcrete between the outer formwork and the inner formwork. During the concrete shotcrete construction process, the concrete forms a dense layer between the arch frame and the outer formwork, and the sprayed and rebounded concrete forms a loose layer between the arch frame and the inner formwork, and finally a protective layer composed of a dense layer, a retaining net, an arch frame and a loose layer is obtained. The protective layer is a structure with a dense outer side and a loose inner side formed with the arch frame as the boundary. The dense layer, the retaining net and the arch frame together form a solid outer layer of tunnel protection to withstand the impact of falling rocks. The inner loose layer is used to buffer the impact force of falling rocks, thereby protecting the tunnel support from being damaged, extending the service life of the tunnel in the solution cavity, and reducing diseases.

[0062] As described above, the method for protecting the tunnel in the dissolution cavity proposed by the present invention is described by way of example with reference to the accompanying drawings. However, it should be understood by those skilled in the art that various improvements can be made to the method for protecting the tunnel in the dissolution cavity proposed by the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the attached claims.

Claims

1. A method for protecting a tunnel in a dissolution cavity, characterized in that: The steps include: An arch frame is arranged around the outer periphery of the tunnel in the dissolution cavity, and a retaining net is hung on the outer side of the arch frame; An outer template is arranged on the outside of the retaining net around the outside of the arch frame, and an inner template is arranged on the inside of the arch frame, so that a concrete spraying space is formed between the outer template and the inner template; Performing concrete spraying construction in the concrete spraying space, so that the concrete forms a dense layer between the arch frame and the outer formwork, and the sprayed and rebounded concrete forms a loose layer between the arch frame and the inner formwork; The dense layer, the retaining net, the arch frame and the loose layer are used as protective layers of the tunnel in the dissolution cavity, and the main structure of the tunnel in the dissolution cavity is protected by the protective layers.

2. The method for protecting a tunnel in a dissolution cavity according to claim 1, characterized in that: The method comprises: arranging an arch frame around the outer periphery of the tunnel in the dissolution cavity, and hanging a retaining net on the outer side of the arch frame, comprising: Determining the size of the arch frame according to the preset thickness of the protective layer and the excavation contour line of the tunnel in the solution cavity; Determine the number of arches provided around the tunnel in the dissolution cavity and the position of each arch according to the length of the tunnel in the dissolution cavity and the size of the arch; According to the number of the arches and the position of each arch, arches are arranged outside the tunnel in the dissolution cavity, and the retaining net is hung outside the enclosed arches and between adjacent arches.

3. The method for protecting a tunnel in a dissolution cavity according to claim 1, characterized in that: An arch frame is set around the outer periphery of the tunnel in the dissolution cavity, and a retaining net is hung on the outer side of the arch frame. When the arch feet on both sides of the arch frame are installed on the plate structure or beam structure of the tunnel in the cavity that crosses the underground river or crack, The arch frame is an I-beam arch frame or a steel bar grid arch frame of models I12 to I14.

4. The method for protecting a tunnel in a dissolution cavity according to claim 1, characterized in that: When the arch feet on both sides of the arch frame are installed on the bedrock of the tunnel in the cavity, The arch frame is an I-beam arch frame of model I18 or above.

5. The method for protecting a tunnel in a dissolution cavity according to claim 1, characterized in that: The retaining net is a steel mesh.

6. The method for protecting a tunnel in a dissolution cavity according to claim 1, characterized in that: An outer template is arranged around the outside of the arch frame on the outside of the retaining net, and an inner template is arranged on the inside of the arch frame. The distance between the arch frame and the outer template is 3-5cm.

7. The method for protecting a tunnel in a dissolution cavity according to claim 1, characterized in that: During the process of concrete spraying construction in the concrete spraying space, The landing point of the sprayed concrete is made on the outer formwork, and the rebound concrete is concentrated between the outer formwork and the inner formwork.

8. The method for protecting a tunnel in a dissolution cavity according to claim 1, characterized in that: During the process of concrete spraying construction in the concrete spraying space, The concrete spraying method is dry spraying or wet spraying.

9. The method for protecting a tunnel in a dissolution cavity according to claim 1, characterized in that: During the process of concrete spraying construction in the concrete spraying space, The concrete rebound rate is at least 50%.

10. The method for protecting a tunnel in a dissolution cavity according to claim 1, characterized in that: When the thickness of the protective layer is less than or equal to 1m, the construction method of the protective layer is single-layer construction; When the thickness of the protective layer is greater than 1 m, the protective layer is constructed in at least two layers.

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