A composite support structure for shallow-buried bias bulk material surrounding rock section of tunnel portal

Abstract

The utility model discloses a kind of composite support structure for tunnel portal shallow-buried bias bulk body surrounding rock section, belong to tunnel engineering support technical field, including support component and the support component arch foot is reinforced by support component, the support component includes the bearing pile support of being located on bearing pile, for providing vertical support, fixed in the connecting plate of lateral support frame outer side wall and be anchored in surrounding rock by anchor rod, for resisting horizontal thrust, and the lock foot anchor pipe that is inclined through lateral support frame arch foot and anchors into surrounding rock. The utility model is three-dimensional rigid locking to arch foot by bottom composite support component, simultaneously realize flexible deformation release stress using top hinged mechanism, effectively solve the problem that supporting structure is easy to produce uneven settlement and instability under bias, significantly improve the security and stability of supporting structure.

Description

Technical Field

[0001] This utility model belongs to the field of civil engineering construction technology, and in particular relates to a composite support structure for shallow buried biased granular surrounding rock sections at tunnel entrances. Background Technology

[0002] In tunnel construction, especially at the tunnel entrance, the stability of the surrounding rock is crucial. Typically, after tunnel excavation, initial support structures such as steel arches and shotcrete are quickly installed to restrain rock deformation, prevent collapse, and provide safety for subsequent construction.

[0003] However, when the tunnel entrance is located in unfavorable geological conditions such as shallow burial or loose surrounding rock, the design and construction of the support structure face enormous challenges. Shallow burial means that the overlying soil is not thick enough to form a stable natural load-bearing arch, and the surrounding rock itself has extremely poor stability. At the same time, the loose surrounding rock has a loose internal structure and lacks cohesion, making it extremely prone to instability and failure after excavation.

[0004] Even more serious is the fact that the surface topography at tunnel entrances is often uneven, such as on hillsides. This leads to asymmetrical rock pressure acting on both sides of the support structure, creating a significant biased pressure effect. Under this biased pressure, traditionally symmetrically designed support structures will bear extremely uneven loads, with the arch foot on the side with greater pressure experiencing excessive vertical and lateral compressive forces. This concentrated and asymmetrical stress state easily leads to uneven settlement and inward lateral slippage of the arch foot on that side, which in turn causes the entire arch frame structure to twist and deform, the arch crown to sink, and ultimately, support failure and tunnel entrance collapse.

[0005] Therefore, this utility model proposes a composite support structure for shallowly buried, biased, loose rock sections at tunnel entrances to address the shortcomings of existing technologies. Utility Model Content

[0006] To overcome the above shortcomings, this utility model provides a composite support structure for shallowly buried, biased, loose rock sections at tunnel entrances. It aims to improve the existing support structures for shallowly buried, biased, loose rock sections at tunnel entrances, where the arch foot support system is relatively simple when dealing with biased rock pressure, making it difficult to effectively resist uneven settlement and lateral slippage, resulting in the risk of overall structural instability.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a composite support structure for a shallowly buried, biased, loosely packed rock section at the tunnel entrance, comprising a support assembly, wherein the support assembly comprises side support frames arranged along both sides of the inner wall of the excavated surrounding rock, and a top support frame connected to the top of the side support frames, and the composite support structure further comprises a support assembly and a hinge mechanism disposed at the docking position of the top support frame; The support assembly is used to reinforce the arch foot of the side support frame. The support assembly includes: a load-bearing pile support, which sits on a load-bearing pile pre-installed in the foundation below the arch foot, with the bottom of the arch foot of the side support frame abutting against the top of the load-bearing pile support; a connecting plate, which is fixed to the outer wall of the side support frame near the surrounding rock and is anchored to the surrounding rock by anchor bolts; and a locking foot anchor pipe, which is inclined and passes through the arch foot of the side support frame and is anchored into the surrounding rock, and is welded and fixed to the side support frame. Furthermore, the top support frame is composed of two parts joined at the center of the arch, and a hinge mechanism is provided at the joint. This hinge mechanism includes a first connecting frame, which is fixed inside one of the top support frames; a second connecting frame, which is fixed inside the other top support frame and rotatably fitted onto the inner wall of the first connecting frame; a locking post, which passes through the second connecting frame and the first connecting frame; and a locking nut, which is threaded onto the tail end of the locking post. Preferably, both the first connecting frame and the second connecting frame are fixed to the interior of the corresponding top support frame by fixing bolts; Preferably, the locking pin passes through through holes respectively opened on the side walls of the second connecting frame and the first connecting frame; Preferably, the top end of the side support frame is connected to the end of the top support frame by a hinge. Preferably, the composite support structure further includes a pipe roof, which is pre-embedded in the surrounding rock outside the support component; Preferably, the pipe roof is a hollow tubular structure, and grouting holes are provided on the pipe wall; Preferably, the composite support structure further includes a steel mesh, which is welded to the inner surface of the support component facing the tunnel interior; Preferably, the anchor pipe is a hollow anchor pipe with grouting function.

[0008] This utility model has the following beneficial effects: 1. This utility model solves the problem of uneven stress on the arch foot, uneven settlement, and lateral slippage leading to structural instability in traditional support structures under eccentric pressure by setting a composite support component consisting of load-bearing pile supports, anchor rods, and inclined locking anchor pipes at the arch foot position of the support structure. It achieves three-dimensional locking of the arch foot from vertical, horizontal, and oblique directions, greatly improving the bearing capacity and deformation resistance of the arch foot, and effectively controlling the tunnel convergence deformation.

[0009] 2. This utility model solves the problem that traditional rigid support structures cannot adapt to the deformation of the surrounding rock and are prone to stress concentration leading to brittle failure by setting a retractable hinge mechanism consisting of inner and outer connecting frames and a locking mechanism on the arch of the support structure. It achieves the effect of allowing the support structure to produce controllable coordinated deformation to actively release part of the surrounding rock pressure, making the structure more uniformly stressed, realizing the synergistic effect between the support structure and the surrounding rock, and improving the structural safety.

[0010] 3. This utility model combines the rigid reinforcement and locking of the arch foot with the flexible deformation release of the arch crown, and is further reinforced by advanced pipe roof grouting. This solves the problem that a single support method is difficult to balance construction safety and long-term stability for complex geological conditions such as shallowly buried, biased, loose surrounding rock. It achieves the construction of a support system that combines rigidity and flexibility and is reinforced in different zones. The structure is lightweight, the stress is reasonable, and it comprehensively prevents large deformation and collapse at the tunnel entrance. Attached Figure Description

[0011] Figure 1 This is a three-dimensional view of a composite support structure for a shallowly buried, biased, granular surrounding rock section at the tunnel entrance, as proposed in this utility model. Figure 2 This is a schematic diagram of a side support frame for a composite support structure for shallowly buried, biased, loose rock sections at tunnel entrances, as proposed in this utility model. Figure 3 This is a schematic diagram of the top support frame of a composite support structure for shallowly buried, biased, loose rock sections at tunnel entrances, as proposed in this utility model. Figure 4 This is a schematic diagram of a locking anchor pipe for a composite support structure used in shallowly buried, biased, loose rock sections at tunnel entrances, as proposed in this utility model.

[0012] Legend: 1. Surrounding rock; 2. Pipe roof; 3. Support components; 301. Side support frame; 302. Top support frame; 303. Steel mesh; 304. First connecting frame; 305. Fixing bolt; 306. Second connecting frame; 307. Locking column; 308. Locking nut; 4. Support components; 401. Bearing pile support; 402. Connecting plate; 403. Anchor bolt; 404. Locking foot anchor pipe. Detailed Implementation

[0013] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0014] Reference Figures 1-4 The present invention provides an embodiment of a composite support structure for a shallow-buried, biased, loose rock section at the tunnel entrance, comprising a support component 3 and a support component 4 for reinforcing the arch foot of the support component 3. The support component 3 is used to provide initial support to the inner wall of the excavated surrounding rock 1, while the support component 4 is used to reliably transfer the load borne by the support component 3 to the foundation and resist the additional stress caused by bias. The entire composite support structure also includes a pre-support pipe roof 2 and a surface-protected steel mesh 303. The pipe roof 2 is pre-embedded in the surrounding rock 1 outside the support component 3 to pre-reinforce the loose surrounding rock 1 before tunnel excavation. The steel mesh 303 is welded to the inner surface of the support component 3 facing the tunnel interior to prevent the surrounding rock 1 from falling off and to enhance the adhesion of the subsequent shotcrete layer. The overall structure of the support component 3 is arched, consisting of side support frames 301 arranged on both sides of the inner wall of the excavated surrounding rock 1 and top support frame 302 connected to the top of the side support frame 301. The top of the side support frame 301 and the end of the top support frame 302 are connected by a hinge. This connection method allows the support structure to undergo a certain degree of coordinated deformation under the pressure of the surrounding rock 1. It also includes a uniquely structured support component 4 and a hinge mechanism set on the top support frame 302. Furthermore, specific structural fit and connection relationships are formed between the support component 4 and the arch foot of the side support frame 301, as well as between the various components of the hinge mechanism.

[0015] Support component 4, as a composite reinforcement system, is three-dimensionally locked at the arch foot of the side support frame 301. The structure and connection relationship of support component 4 are as follows: the bottom of the bearing pile support 401 rests on the bearing pile pre-installed in the foundation below the arch foot, providing a solid vertical foundation for the entire support component 3. The bottom of the arch foot of the side support frame 301 directly abuts against the top of the bearing pile support 401 to transfer the upper load. Simultaneously, the connecting plate 402 is fixed to the outer wall of the side support frame 301 near the surrounding rock 1 by welding or bolts. The anchor rod 403 passes through the connecting plate 402 and is deeply anchored in the surrounding rock 1. This provides strong horizontal resistance to prevent the support frame from moving inward into the tunnel. In addition, the locking anchor pipe 404 is set at an angle, with one end passing through the arch foot of the side support frame 301 and anchored deep into the foundation of the surrounding rock 1, and the other end welded and fixed to the side support frame 301. This oblique locking method can resist the combined forces of vertical settlement and horizontal displacement at the same time. The arch foot support system, which is composed of the bearing pile support 401, connecting plate 402, anchor rod 403 and locking anchor pipe 404, locks the arch foot in all directions from vertical, horizontal and oblique dimensions, which greatly enhances the bearing capacity and deformation resistance of the arch foot. The top support frame 302 is composed of two parts joined together at the center of the arch, and a precision hinge mechanism is provided at the joint position. The detailed structure of the hinge mechanism is as follows: the first connecting frame 304 is fixed to the internal cavity of one of the top support frames 302 by fixing bolts 305, and the second connecting frame 306 is also fixed to the internal cavity of the other top support frame 302 by fixing bolts 305. In the assembled state, the second connecting frame 306 is rotatably fitted onto the inner wall of the first connecting frame 304, forming a joint that allows relative rotation. In order to control this rotation and provide locking as needed, the locking pin 307 passes through through holes respectively opened on the side walls of the second connecting frame 306 and the first connecting frame 304. Finally, the locking nut 308 is screwed onto the tail end of the locking pin 307 by means of a threaded connection. By adjusting the tightness of the locking nut 308, the tightness of the connection between the first connecting frame 304 and the second connecting frame 306 can be controlled, thereby realizing the adjustment from allowing slight rotation to release stress to fully locking to form a rigid connection. It also includes pipe roof 2, which is driven into the surrounding rock 1 along the outer side of the tunnel design excavation outline and forms an advanced support system, providing a safe working space for the installation of subsequent support components 3. The pipe roof 2 is a hollow tubular structure with grouting holes on the pipe wall. Through these grouting holes, cement slurry and other consolidation materials can be injected into the surrounding loose surrounding rock 1, thereby significantly improving the self-stabilizing capacity of the surrounding rock 1. It also includes steel mesh 303, the overall shape of which matches the inner outline of the support component 3, and is firmly connected to the inner surface of the side support frame 301 and the top support frame 302 facing the tunnel interior by welding. The anchor pipe 404 is preferably a hollow anchor pipe with grouting function. After the anchor pipe 404 is driven into the predetermined position, grout can also be injected into the surrounding foundation through the internal channel, thereby improving the overall bearing capacity of the arch foot foundation.

[0016] Working principle: Before tunnel excavation, the pipe roof 2 with grouting holes is first driven into the loose surrounding rock 1 along the outer contour of the tunnel arch and grouting is carried out. After the grout solidifies, a pre-reinforced bearing arch is formed in the surrounding rock 1, which provides stable conditions for subsequent excavation. After the excavation is completed, the support component 3 consisting of side support frame 301 and top support frame 302 is immediately installed. The bottom of the arch foot of the side support frame 301 is accurately placed on the bearing pile support 401, and the bearing pile support 401 transfers the load to the bearing pile below, forming a reliable vertical support. Next, the arch foot is reinforced and locked in a composite manner. The connecting plate 402 is fixed to the outer wall of the side support frame 301 and anchored to the surrounding rock 1 by the anchor rod 403 to resist the horizontal thrust. At the same time, the locking foot anchor pipe 404 with grouting function is driven obliquely into the foundation and welded to the side support frame 301 to complete the three-dimensional locking of the arch foot. Finally, the steel mesh 303 is welded to the inner surface of the support component 3. During long-term load-bearing, when the pressure of the surrounding rock 1 increases, the hinge mechanism set at the arch position of the top support frame 302 begins to play its role. The second connecting frame 306 and the first connecting frame 304 are allowed to generate a small relative rotation. This coordinated deformation can actively release some of the concentrated stress, avoiding excessive stress concentration and damage to the support structure. The locking column 307 and the locking nut 308 ensure that this deformation is controllable. By combining the rigid and strong locking of the bottom support component 4 with the flexible deformation release of the top hinge mechanism, the rigidity and flexibility of the entire support system are achieved, effectively coping with the complex stress conditions brought about by the shallow buried biased surrounding rock.

Claims

1. A composite support structure for a shallowly buried, biased, granular surrounding rock section at the tunnel entrance, comprising: The support assembly (3) includes a side support frame (301) arranged on both sides of the inner wall of the excavation of the surrounding rock (1), and a top support frame (302) connected to the top of the side support frame (301). Its characteristic is that it further includes: Support assembly (4), which is used to reinforce the arch foot of the side support frame (301), the support assembly (4) includes: The bearing pile support (401) is located on the bearing piles pre-installed in the foundation below the arch foot, and the bottom of the arch foot of the side support frame (301) abuts against the top of the bearing pile support (401); A connecting plate (402) is fixed to the outer wall of the side support frame (301) near the surrounding rock (1), and the connecting plate (402) is anchored in the surrounding rock (1) by anchor bolts (403); And a locking foot anchor pipe (404), which is inclined and passes through the arch foot of the side support frame (301) and anchored into the surrounding rock (1), and the locking foot anchor pipe (404) is welded and fixed to the side support frame (301); The top support frame (302) is composed of two parts joined together at the center of the arch, and a hinge mechanism is provided at the joint position. The hinge mechanism includes: A first connecting frame (304) is fixed inside one of the top support frames (302); The second connecting frame (306) is fixed inside another top support frame (302), and the second connecting frame (306) is rotatably sleeved on the inner wall of the first connecting frame (304); Locking post (307) passes through the second connecting frame (306) and the first connecting frame (304); And a locking nut (308), which is threaded to the end of the locking post (307).

2. The composite support structure for shallowly buried, biased, granular surrounding rock sections at tunnel entrances according to claim 1, characterized in that: The first connecting frame (304) and the second connecting frame (306) are both fixed to the interior of the corresponding top support frame (302) by fixing bolts (305).

3. The composite support structure for shallowly buried, biased, granular surrounding rock sections at tunnel entrances according to claim 2, characterized in that: The locking pin (307) passes through through holes respectively opened on the side walls of the second connecting frame (306) and the first connecting frame (304).

4. The composite support structure for shallowly buried, biased, granular surrounding rock sections at tunnel entrances according to claim 1, characterized in that: The top end of the side support frame (301) is connected to the end of the top support frame (302) by a hinge.

5. The composite support structure for shallowly buried, biased, granular surrounding rock sections at tunnel entrances according to claim 1, characterized in that: It also includes a pipe roof (2), which is pre-embedded in the surrounding rock (1) outside the support component (3).

6. The composite support structure for shallowly buried, biased, granular surrounding rock sections at tunnel entrances according to claim 5, characterized in that: The pipe shed (2) is a hollow tubular structure, and grouting holes are provided on the pipe wall.

7. The composite support structure for shallowly buried, biased, granular surrounding rock sections at tunnel entrances according to claim 1, characterized in that: It also includes a steel mesh (303) welded to the inner surface of the support assembly (3) facing the tunnel interior.

8. The composite support structure for shallowly buried, biased, granular surrounding rock sections at tunnel entrances according to claim 1, characterized in that: The anchor pipe (404) is a hollow anchor pipe with grouting function.

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