A composite support structure for high ground stress soft rock large deformation diversion tunnel

Abstract

The utility model discloses a kind of composite support structure for high ground stress soft rock large deformation water diversion tunnel, including tunnel body, the initial support system of setting in the inner wall of tunnel body and secondary lining, the initial support system includes the outer layer initial support with the inner wall contact of tunnel body, the inner layer initial support located in the outer layer initial support inside;Between the outer layer initial support and inner layer initial support, local or all pass through EPS concrete filling.The utility model provides a kind of composite support structure for high ground stress soft rock large deformation water diversion tunnel, to solve the problem that there is greater support difficulty in prior art for high ground stress soft weak surrounding rock water diversion tunnel, realize the purpose of extrusion deformation of high ground stress soft rock water diversion tunnel surrounding rock by composite support structure fully releasing.

Description

Technical Field

[0001] This utility model relates to the field of soft rock tunnel construction, specifically to a composite support structure for water diversion tunnels in soft rock with high ground stress and large deformation. Background Technology

[0002] Many water diversion tunnel projects in western China encountered weak rock strata during construction. Under the combined effects of in-situ stress and groundwater, the surrounding rock was prone to large deformations. The softer the surrounding rock, the higher the in-situ stress, and the richer the groundwater content, the greater the deformation of the surrounding rock.

[0003] The deformation of the surrounding rock during the excavation of a water diversion tunnel is essentially a process of gradual release of ground stress. During this process, the surrounding rock gradually transitions from a intact state to a loose and fragmented state, significantly reducing its bearing capacity. During the construction of the water diversion tunnel, after the excavation of a certain section, initial support is immediately implemented according to the construction sequence, including installing system anchors and erecting steel arches. Excavation and support then continue. During this process, the deformation of the surrounding rock at the aforementioned section continuously increases. If the deformation of the tunnel's surrounding rock is too large, it will cause the deformation of the initial support structure to increase simultaneously, ultimately leading to excessive deformation of the initial support, a decrease in its bearing capacity, and a significant reduction in the stability of the surrounding rock.

[0004] Therefore, water diversion tunnels with high ground stress and weak surrounding rock present significant support challenges. During the release of ground stress, the support structure is prone to large deformations, which is detrimental to the stability and safety of the water diversion tunnel during construction and operation. Utility Model Content

[0005] This utility model provides a composite support structure for water diversion tunnels with high ground stress and large deformation in soft rock, in order to solve the problem of the great difficulty in supporting water diversion tunnels with high ground stress and weak surrounding rock in the prior art, and to achieve the purpose of fully releasing the compression deformation of the surrounding rock of water diversion tunnels with high ground stress and soft rock through the composite support structure.

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

[0007] A composite support structure for a water diversion tunnel in high-stress soft rock with large deformation includes a tunnel body, an initial support system installed on the inner wall of the tunnel body, and a secondary lining. The initial support system includes an outer initial support in contact with the inner wall of the tunnel body and an inner initial support located inside the outer initial support. The space between the outer initial support and the inner initial support is partially or completely filled with EPS concrete.

[0008] To address the significant challenges in supporting water diversion tunnels in high-stress, soft surrounding rock conditions in existing technologies, this invention proposes a composite support structure for water diversion tunnels in high-stress, soft rock conditions with large deformations. The secondary lining can be achieved using existing technologies. This application primarily focuses on improving and optimizing the initial support system. Specifically, the initial support system comprises a double-layer structure: an outer initial support layer and an inner initial support layer. The outer initial support layer directly contacts the inner wall of the tunnel body, while the inner initial support layer is located inside the outer initial support layer. The space between the outer and inner initial support layers is filled with EPS concrete. The EPS concrete can be entirely installed circumferentially between the inner and outer initial support layers, or it can be used only in localized areas of the inner and outer initial support layers.

[0009] This application utilizes EPS concrete to absorb the deformation of the surrounding rock caused by the gradual release of ground stress during tunnel construction, and also absorbs the rheological deformation of the surrounding rock during tunnel operation. The inner layer of initial support enhances the overall deformation resistance of the initial support system, reducing the risk of damage to the support structure of the water diversion tunnel due to surrounding rock deformation during later operation. In summary, this application can fully release the compressive deformation of the surrounding rock in high-stress soft rock water diversion tunnels, and ensures the load-bearing characteristics of the initial support system during the release of this deformation.

[0010] It should be noted that the EPS concrete in this application can use existing formulas / components. EPS concrete, which is lightweight concrete that uses polystyrene particles to replace part or all of the coarse aggregate in traditional concrete, has the characteristics of low density and lightweight filler, and has good compressibility. Therefore, it can generate a relatively large amount of compressive deformation when encountering later surrounding rock deformation, thereby consuming and releasing the surrounding rock deformation load, further reducing the risk of torsion, fracture and other damage to the support structure, and thus significantly improving the overall stability and safety of the support structure.

[0011] Furthermore, the outer initial support and the inner initial support are filled with EPS concrete in the arch area on both sides of the tunnel body; the remaining part of the outer initial support is in direct contact with the inner initial support.

[0012] This solution confines the EPS concrete to the arched waist region on both sides of the tunnel body. Specifically, a layer of EPS concrete is sandwiched between the outer and inner initial support layers in the arched waist region of the tunnel body. In the remaining areas of the tunnel body, the outer and inner initial support layers are in direct contact. The reason for this arrangement is that the inventors discovered during their research that under in-situ stress, especially when the horizontal tectonic stress is high, the horizontal deformation of the surrounding rock at the arched waist region can easily exceed the allowable range, leading to a decrease in the overall bearing capacity of the support structure or even damage. Therefore, by filling the arched waist region with EPS concrete, the compression deformation of the surrounding rock in high-stress soft rock water diversion tunnels can be fully released while reducing construction costs and improving construction efficiency.

[0013] Furthermore, the tunnel body has enlarged excavation zones on both sides of the arch waist area, and the extent of the enlarged excavation zones is directly opposite the extent of the EPS concrete filling.

[0014] For any tunnel construction, there must be an original design excavation outline, defined as the original design excavation outline. This scheme, based on the original design excavation outline, appropriately expands the excavation on both sides of the arch waist to form an expanded excavation zone, and makes the extent of the expanded excavation zone match the filling range of EPS concrete. This helps to maintain the tunnel structure dimensions close to the original design even after the EPS concrete is filled.

[0015] Furthermore, along the longitudinal direction, the thickness of the EPS concrete gradually decreases from the middle towards both ends. That is, the thickness of the EPS concrete gradually decreases from the central area of ​​the arch waist upwards and to the upper and lower sides, which is more conducive to reducing construction costs and improving construction efficiency.

[0016] Furthermore, the inner initial support is a steel fiber reinforced concrete layer.

[0017] Steel fiber reinforced concrete is a multiphase composite concrete material formed by incorporating randomly distributed short steel fibers into ordinary concrete. These randomly distributed steel fibers can effectively inhibit the propagation of microcracks and the formation of macrocracks within the concrete. In this application, it can significantly improve the deformation resistance of the initial support system and reduce the risk of failure of the support structure during subsequent deformation of the surrounding rock. The steel fiber reinforced concrete layer in this application can utilize existing steel fiber reinforced concrete formulations / components.

[0018] Furthermore, the outer initial support includes several steel arch frames that match the inner wall of the tunnel body. The shape of the steel arch frames matches the inner wall of the excavated tunnel body, which facilitates ensuring sufficient contact between each steel arch frame and the tunnel wall, thus helping to ensure the effectiveness of the initial support.

[0019] Furthermore, each steel arch frame comprises several segments, with adjacent segments connected by pressure-relief members.

[0020] In water diversion tunnels, the loads generated by the loosening and deformation of the surrounding rock act on each segment of the steel arch frame, and the segments tend to compress and / or misalign. By compressing, stretching or torsioning the pressure members, the loads generated by the deformation of the surrounding rock are consumed. Therefore, the probability of the steel arch frame bending, torsion or even bending can be significantly reduced, and the ability to release ground stress during later operation can be significantly improved. In this way, the support resistance of the entire initial support system is improved and the stability of the water diversion tunnel is improved.

[0021] Furthermore, the pressure-relief component is a metal tube, the axis of which is perpendicular to the line connecting two adjacent segments. This design provides strong resistance to compression through the metal tube, which is beneficial for dissipating ground stress.

[0022] Furthermore, the metal pipe is fixedly clamped between two parallel first connecting plates, which are used to connect with the segment. This design, using two first connecting plates, facilitates the rapid installation of the pressure-relief components during on-site assembly of the steel arch frame, thereby improving construction efficiency.

[0023] Furthermore, a second connecting plate is provided at the end of the segment, and the first connecting plate and the second connecting plate are connected by bolts. When installing the pressure relief member, the first connecting plates at both ends are bolted to the second connecting plates of the two segments respectively.

[0024] Compared with the prior art, this utility model has at least the following advantages and beneficial effects:

[0025] 1. This utility model discloses a composite support structure for water diversion tunnels with high ground stress and large deformation in soft rock. During tunnel construction, EPS concrete absorbs the deformation of the surrounding rock caused by the gradual release of ground stress, and also absorbs the rheological deformation of the surrounding rock during the tunnel operation period. The inner layer of initial support improves the overall deformation resistance of the initial support system and reduces the risk of damage to the support structure of the water diversion tunnel due to the deformation of the surrounding rock during later use.

[0026] 2. This utility model provides a composite support structure for water diversion tunnels in soft rock with high ground stress and large deformation. It can fully release the compression deformation of the surrounding rock in the water diversion tunnel in soft rock with high ground stress, and ensure the bearing characteristics of the initial support system during the process of releasing the compression deformation of the surrounding rock.

[0027] 3. This utility model provides a composite support structure for water diversion tunnels with high ground stress and large deformation in soft rock. By filling the arch waist area with EPS concrete, it can fully release the compression deformation of the surrounding rock of the water diversion tunnel with high ground stress and reduce construction costs and improve construction efficiency.

[0028] 4. This utility model provides a composite support structure for water diversion tunnels in soft rock with high ground stress and large deformation. The steel fiber reinforced concrete layer can significantly improve the deformation resistance of the initial support system and reduce the risk of damage to the support structure during subsequent deformation of the surrounding rock.

[0029] 5. This utility model provides a composite support structure for water diversion tunnels in soft rock with high ground stress and large deformation. By compressing, stretching, or torturing the pressure-relieving components, the load generated by the deformation of the surrounding rock is consumed. Therefore, it can significantly reduce the probability of bending, twisting, or even bending of the steel arch frame, significantly improve the ability to release ground stress during later operation, and thus improve the support resistance of the entire initial support system and the stability of the water diversion tunnel. Attached Figure Description

[0030] 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:

[0031] Figure 1 This is an overall schematic diagram of a specific embodiment of the present utility model;

[0032] Figure 2 This is a schematic diagram of the enlarged excavation area in a specific embodiment of this utility model;

[0033] Figure 3 This is a schematic diagram of the connection of the pressure relief component in a specific embodiment of this utility model.

[0034] A schematic diagram of the rigid plate structure.

[0035] The attached diagram shows the markings and corresponding component names:

[0036] 1-Secondary lining, 2-Outer initial support, 201-Segmentation, 202-Pressure relief component, 203-First connecting plate, 204-Bolt, 205-Second connecting plate, 3-Inner initial support, 4-EPS concrete, 5-System anchor bolt, 6-Expansion outline, 7-Original design excavation outline. Detailed Implementation

[0037] 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. In the description of this application, it should be understood that terms such as "front," "rear," "left," "right," "up," "down," "vertical," "horizontal," "high," "low," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application.

[0038] Example 1:

[0039] like Figure 1 The composite support structure shown is for a water diversion tunnel with high ground stress and large deformation in soft rock. It includes a tunnel body, an initial support system installed on the inner wall of the tunnel body, and a secondary lining 1. The initial support system includes an outer initial support 2 in contact with the inner wall of the tunnel body and an inner initial support 3 located inside the outer initial support 2. The space between the outer initial support 2 and the inner initial support 3 is partially or completely filled with EPS concrete 4.

[0040] The outer initial support 2 and the inner initial support 3 are filled with EPS concrete 4 in the arch area on both sides of the tunnel body; the remaining part of the outer initial support 2 is in direct contact with the inner initial support 3.

[0041] The radial thickness of the EPS concrete 4 gradually decreases from the middle to both ends.

[0042] In this embodiment, the inner initial support 3 is a layer of steel fiber reinforced concrete.

[0043] like Figure 2 As shown, based on the original excavation outline 7, this embodiment expands the tunnel body outwards in the arched waist area on both sides to obtain an expanded excavation zone. The extent of the expanded excavation zone is directly opposite the extent of the EPS concrete filling 4. In this embodiment, the outline of the expanded excavation zone is defined as the expanded excavation outline 6.

[0044] The construction process in this embodiment includes the following steps:

[0045] During the construction of the water diversion tunnel, a certain degree of enlargement is first carried out at the arch waist position. The specific amount of enlargement can be determined according to the actual site conditions to form an enlarged excavation zone.

[0046] Install the outer initial support 2 and spray conventional concrete;

[0047] EPS relief concrete is applied to the arch waist area so that the inner contour line of the completed EPS concrete is the same as or close to the inner contour line of the original initial support.

[0048] Apply the inner initial support 3, namely sprayed steel fiber concrete;

[0049] Secondary lining was then constructed to complete the construction of the composite support structure.

[0050] As can be seen, this embodiment fully releases the geostress stored in the surrounding rock by widening the excavation of the surrounding rock at the arch waist and the initial support of the outer layer, thereby allowing the surrounding rock to undergo a large deformation, which is especially suitable for use in water diversion tunnels with high geostress soft rock.

[0051] Example 2:

[0052] A composite support structure for water diversion tunnels in soft rock with high ground stress and large deformation, based on Example 1, wherein the outer initial support 2 includes several steel arch frames that match the inner wall of the tunnel body.

[0053] like Figure 3 As shown, each steel arch frame includes several segments 201, and adjacent segments 201 are connected by a pressure relief member 202.

[0054] In this embodiment, the pressure-relief member 202 is a metal tube, the axis of which is perpendicular to the line connecting two adjacent segments 201. The metal tube is fixedly clamped between two parallel first connecting plates 203, which are used to connect to the segments 201.

[0055] In this embodiment, the pressure member 202 and the first connecting plate 203 are both made of iron or steel.

[0056] In this embodiment, two first connecting plates 203 are respectively welded to the opposite side walls in the radial direction of the metal pipe.

[0057] Preferably, a second connecting plate 205 is provided at the end of the segment 201, and the first connecting plate 203 and the second connecting plate 205 are connected by bolts 204.

[0058] 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.

[0059] 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. Additionally, the term "connection" as used herein, unless otherwise specified, can refer to a direct connection or an indirect connection via other components.

Claims

1. A composite support structure for a water diversion tunnel in high-stress soft rock with large deformation, comprising a tunnel body, an initial support system installed on the inner wall of the tunnel body, and a secondary lining (1), characterized in that, The initial support system includes an outer initial support (2) that contacts the inner wall of the tunnel body and an inner initial support (3) located inside the outer initial support (2); the space between the outer initial support (2) and the inner initial support (3) is partially or completely filled with EPS concrete (4).

2. The composite support structure for a water diversion tunnel in high-stress soft rock with large deformation according to claim 1, characterized in that, Between the outer initial support (2) and the inner initial support (3), EPS concrete (4) is used to fill the arch waist area on both sides of the tunnel body; the remaining part of the outer initial support (2) is in direct contact with the inner initial support (3).

3. A composite support structure for a water diversion tunnel in high-stress soft rock with large deformation, as described in claim 2, is characterized in that... The tunnel body has an enlarged excavation zone on both sides of the arch waist area, and the extent of the enlarged excavation zone is directly opposite to the extent of filling the EPS concrete (4).

4. A composite support structure for a water diversion tunnel in high-stress soft rock with large deformation according to claim 1, characterized in that, Along the longitudinal direction, the thickness of the EPS concrete (4) gradually decreases from the middle to both ends.

5. A composite support structure for a water diversion tunnel in high-stress soft rock with large deformation according to claim 1, characterized in that, The inner initial support (3) is a steel fiber reinforced concrete layer.

6. A composite support structure for a water diversion tunnel in high-stress soft rock with large deformation according to claim 1, characterized in that, The outer initial support (2) includes several steel arch frames that match the inner wall of the tunnel body.

7. A composite support structure for a water diversion tunnel in high-stress soft rock with large deformation according to claim 6, characterized in that, Each steel arch frame comprises several segments (201), and adjacent segments (201) are connected by a pressure relief member (202).

8. A composite support structure for a water diversion tunnel in high-stress soft rock with large deformation according to claim 7, characterized in that, The pressure relief member (202) is a metal tube, and the axis of the metal tube is perpendicular to the line connecting two adjacent segments (201).

9. A composite support structure for a water diversion tunnel in high-stress soft rock with large deformation, as described in claim 8, is characterized in that... The metal tube is fixedly clamped between two parallel first connecting plates (203), which are used to connect with the segment (201).

10. A composite support structure for a water diversion tunnel in high-stress soft rock with large deformation according to claim 9, characterized in that, The end of the segment (201) is provided with a second connecting plate (205), and the first connecting plate (203) and the second connecting plate (205) are connected by bolts (204).

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