Composite support structure for large deformation of soft rock tunnel surrounding rock caused by tectonic stress

Abstract

The utility model discloses a kind of composite support structure for the large deformation of soft rock tunnel surrounding rock caused by tectonic stress, including tunnel body, the initial support system and secondary lining system of setting in tunnel body inner wall, the arch waist of the tunnel body has expansion area, and the expansion area is filled with concrete.The utility model provides composite support structure for the large deformation of soft rock tunnel surrounding rock caused by tectonic stress, to solve the problem that initial support is subjected to horizontal direction tectonic stress and generates larger deformation in arch waist part in prior art, realize the purpose of improving the support resistance of horizontal direction tectonic stress, reducing the damage risk of initial support structure, reducing construction risk.

Description

Technical Field

[0001] This utility model relates to the field of tunnel construction, specifically to a composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress. Background Technology

[0002] For tunnel construction in soft rock under high ground stress, large deformation of weak surrounding rock is a major engineering challenge. According to monitoring data from multiple tunnels, the final deformation of weak surrounding rock under high ground stress conditions can typically reach more than 30 cm, and in some cases even more than 1 meter.

[0003] The tectonic stress in the horizontal direction underground is the main cause of large deformation of the surrounding rock in the arch waist of the tunnel. Generally, the greater the value of the tectonic stress in the horizontal direction, the greater the value of the horizontal compression deformation of the surrounding rock in the arch waist.

[0004] In existing technologies, after a section of a tunnel is excavated, initial support is usually installed immediately according to the construction procedure, followed by continued excavation and support. During this process, under the action of tectonic stress in the horizontal direction, the deformation of the surrounding rock in the arch waist of the excavated section will continue to increase, and the deformation of the installed initial support structure will also increase. When the deformation of the initial support structure is too large, it will lead to a decrease in the bearing capacity of the support structure, which will lead to a vicious cycle of continued increase in the deformation of the weak surrounding rock, resulting in a significant increase in construction risks. Utility Model Content

[0005] This utility model provides a composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress, in order to solve the problem of large deformation in the arch waist of the initial support under the action of horizontal tectonic stress in the prior art, thereby achieving the purpose of improving the support resistance to horizontal tectonic stress, reducing the risk of damage to the initial support structure, and reducing construction risks.

[0006] This utility model is achieved through the following technical solution:

[0007] A composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress includes a tunnel body, an initial support system and a secondary lining system installed on the inner wall of the tunnel body, wherein the tunnel body has an enlarged excavation zone at the arch waist, and the enlarged excavation zone is filled with concrete.

[0008] To address the problem in existing technologies where initial support is subject to horizontal tectonic stress and prone to significant deformation at the tunnel arch waist, the inventors' team discovered during their research that the large deformation of initial support caused by horizontal tectonic stress is mainly concentrated in the tunnel arch waist area. Therefore, this invention proposes a composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress. Both the initial support system and the secondary lining system can utilize existing technologies. Those skilled in the art should understand that the tunnel body includes the arch crown, arch waist, and arch bottom. This application sets up an enlarged excavation zone at the arch waist, that is, over-excavating the surrounding rock outwards at the arch waist to form an enlarged excavation zone protruding from the tunnel body area. This application also uses concrete to fill the enlarged excavation zone, that is, filling the over-excavated area with concrete up to the original design excavation outline of the tunnel.

[0009] This application, by filling the arch waist excavation area with concrete, can significantly improve the resistance to horizontal tectonic stress, thereby reducing the degree of deformation of the initial support due to horizontal tectonic stress during construction, reducing the risk of damage to the initial support, and improving construction safety.

[0010] Furthermore, the concrete filling the excavated area is EPS concrete.

[0011] The EPS concrete described in this scheme is a lightweight concrete that uses polystyrene particles to replace part or all of the coarse aggregate in traditional concrete. It has the characteristics of low density and lightweight filling. In this application, it is filled in the excavation zone and has good compressibility. Therefore, when it encounters horizontal tectonic stress, it can generate relatively large lateral compressive deformation, thereby consuming and releasing the stress, more effectively reducing the risk of large deformation in the initial support, and thus improving the overall stability and reliability of the support structure.

[0012] The EPS concrete used in this application can be achieved using existing technology.

[0013] Furthermore, on the cross-section of the tunnel body, the widened excavation zone and the surrounding rock have interconnected first and second contour lines. Those skilled in the art should understand that the cross-section of the tunnel body described in this application refers to a cross-section through a longitudinal plane perpendicular to the tunnel axis. In this solution, the outer contour of the widened excavation zone includes a first contour line and a second contour line, and the first and second contour lines are interconnected.

[0014] Furthermore, the bottom end of the first contour line is located at the bottom of the tunnel arch, and the top end of the second contour line is located at the top of the tunnel arch waist, ensuring that the excavation zone completely covers the arch waist area, improving the protection of the tunnel arch waist area and further reducing the risk of large deformation in the initial support. It is also easy to understand that the top end of the first contour line connects to the bottom end of the second contour line.

[0015] Furthermore, both the first and second contour lines are straight lines, which helps to reduce the construction difficulty of the excavation and widening area, thereby quickly completing the construction of the widening area and reducing the construction period, so as to resist the horizontal tectonic stress as soon as possible through the filling concrete.

[0016] Furthermore, an obtuse angle is formed between the first and second contour lines. In this scheme, the excavation zone has an approximately obtuse triangular structure in the vertical direction, thicker in the middle and thinner at both ends. Consequently, the filling concrete also has an approximately obtuse triangular structure, which is more conducive to protecting the central area of ​​the initial support and reducing the risk of large inward deformation in the central part of the initial support.

[0017] Furthermore, the angle between the first contour line and the second contour line is 120°~160°.

[0018] Furthermore, the first contour line and the second contour line are of equal length.

[0019] Furthermore, the initial support system includes several anchor bolts.

[0020] Furthermore, the initial support system includes a steel arch frame erected on the tunnel wall and an initial support concrete layer sprayed on the outside of the steel arch frame.

[0021] Compared with the prior art, this utility model has at least the following advantages and beneficial effects:

[0022] 1. This utility model is a composite support structure for soft rock tunnels with large deformation of surrounding rock caused by tectonic stress. By filling the arch waist excavation area with concrete, it can significantly improve the resistance to horizontal tectonic stress, thereby reducing the degree of deformation of the initial support caused by horizontal tectonic stress during construction, reducing the risk of damage to the initial support, and improving construction safety.

[0023] 2. This utility model is used for a composite support structure for soft rock tunnels with large deformation of surrounding rock caused by tectonic stress. EPS concrete is used to fill the excavation area. When encountering horizontal tectonic stress, it can generate relatively large lateral compression deformation, thereby consuming and releasing the stress, which can more effectively reduce the risk of large deformation of the initial support, and thus improve the overall stability and reliability of the support structure. Attached Figure Description

[0024] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0025] Figure 1 This is a cross-sectional schematic diagram of a specific embodiment of the present utility model.

[0026] The attached diagram shows the markings and corresponding component names:

[0027] 1-Initial support system, 2-Secondary lining system, 3-Expanded excavation zone, 4-First outline, 5-Second outline, 6-Anchor bolt. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0029] Example 1:

[0030] like Figure 1 The composite support structure shown is for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress, including the tunnel body, an initial support system 1 installed on the inner wall of the tunnel body, and a secondary lining system 2. The initial support system 1 includes several anchor bolts 6, a steel arch frame erected on the tunnel body wall, and an initial support concrete layer sprayed on the outside of the steel arch frame.

[0031] In this embodiment, an enlarged excavation zone 3 is set at both sides of the arch waist of the tunnel body, and EPS concrete is filled in the enlarged excavation zone 3.

[0032] On the cross-section of the tunnel body, the widened excavation zone 3 and the surrounding rock are connected by a first contour line 4 and a second contour line 5. The bottom end of the first contour line 4 is located at the bottom of the tunnel body's arch, and the top end of the second contour line 5 is located at the top of the tunnel body's arch waist.

[0033] In this embodiment, the first contour line 4 and the second contour line 5 are both straight lines, and an obtuse angle is formed between them.

[0034] In this embodiment, the included angle between the first contour line 4 and the second contour line 5 is 120°~160°, preferably 150°.

[0035] In a more preferred embodiment, the first contour line 4 and the second contour line 5 are of equal length.

[0036] The construction method in this embodiment includes the following steps:

[0037] S1. Determine the excavation depth of the expanded excavation zone 3;

[0038] S2. During the tunnel excavation process, the enlarged excavation area 3 is over-excavated at the arch waist position, and then EPS concrete is used to fill it to the original design excavation outline.

[0039] S3. After filling with EPS concrete, erect a steel arch frame and spray initial support concrete.

[0040] S4. After the deformation of the cross section stabilizes, secondary lining shall be constructed; during this period, excavation of the working face may continue.

[0041] The excavation depth of the widened excavation zone 3 can be set based on experience or adapted to the existing deformation monitoring data of the surrounding rock corresponding to the tunnel, and no specific limit is made here.

[0042] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

[0043] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

Claims

1. A composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress, comprising a tunnel body, an initial support system (1) installed on the inner wall of the tunnel body, and a secondary lining system (2), characterized in that, The tunnel body has an enlarged excavation zone (3) at the arch waist, and the enlarged excavation zone (3) is filled with concrete.

2. The composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress according to claim 1, characterized in that, The concrete filling the excavated area (3) is EPS concrete.

3. The composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress according to claim 1, characterized in that, On the cross section of the tunnel body, the excavation zone (3) and the surrounding rock have a first contour line (4) and a second contour line (5) that are interconnected.

4. The composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress according to claim 3, characterized in that, The bottom of the first contour line (4) is located at the bottom of the tunnel body, and the top of the second contour line (5) is located at the top of the tunnel body.

5. The composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress according to claim 3, characterized in that, Both the first contour line (4) and the second contour line (5) are straight lines.

6. The composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress according to claim 5, characterized in that, An obtuse angle is formed between the first contour line (4) and the second contour line (5).

7. The composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress according to claim 6, characterized in that, The included angle between the first contour line (4) and the second contour line (5) is 120°~160°.

8. The composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress according to claim 5, characterized in that, The first contour line (4) and the second contour line (5) are of equal length.

9. The composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress, as described in any one of claims 1 to 8, is characterized in that, The initial support system (1) includes several anchor bolts (6).

10. The composite support structure for large deformation of surrounding rock in soft rock tunnels caused by tectonic stress, as described in any one of claims 1 to 8, is characterized in that, The initial support system (1) includes a steel arch frame erected on the tunnel wall and an initial support concrete layer sprayed on the outside of the steel arch frame.

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