Tunnel support structure for crossing fault fracture zones

Abstract

This utility model discloses a support structure for tunnels traversing fault fracture zones, solving the technical problem of easy deformation at the connection of steel arch frames in the prior art. The support structure for tunnels traversing fault fracture zones includes steel arch frames arranged at intervals along the route. Each steel arch frame is composed of multiple steel sections connected sequentially to form an arch shape via flanges and bolts. The support structure also includes longitudinal beams connecting adjacent steel arch frames and arranged at intervals along the radial direction of the route, as well as connectors connecting adjacent longitudinal beams. The longitudinal beams include: longitudinal rods placed above, below, to the left, and to the right of the flanges; and stirrups that fix the four longitudinal rods placed above, below, to the left, and to the right of the flanges together radially along the route. The stirrups are arranged at intervals along the route.

Description

Technical Field

[0001] This utility model relates to the technical field of tunnel support structures, and more specifically, to a tunnel support structure for tunnels traversing fault fracture zones. Background Technology

[0002] Fault fracture zones are complex geological zones formed on both sides of a fault (i.e., a fractured surface where rock has fractured and shifted significantly) after the Earth's crustal lithosphere has fractured and moved under tectonic stress. These zones consist of broken rock blocks, rock debris, fault gouge, and fissures. They are common complex geological sections in tunnel construction, characterized by harsh geological conditions, poor stability, and a high susceptibility to disasters such as collapses, water inrushes, and mudslides. The support structure design of tunnels in fault fracture zones must consider three major functions: "advanced pre-reinforcement, immediate support, and long-term load-bearing capacity." It typically consists of advanced support, initial support, secondary lining, and auxiliary measures, with each component working together to control surrounding rock deformation and disaster risks.

[0003] Typically, pre-support involves reinforcing or supporting the fractured surrounding rock in front of the tunnel face before excavation, creating safe conditions for the excavation operation. Initial support must be constructed immediately after excavation; it is the "first line of defense" after excavation, quickly sealing the surrounding rock, controlling deformation, and bearing the initial stress released by the surrounding rock. Secondary lining is the permanent load-bearing structure of the tunnel, constructed after the initial support deformation has basically stabilized. It bears the residual stress of the surrounding rock, water pressure, and external loads, while also serving as the final barrier for waterproofing.

[0004] Traditional initial support includes anchor bolts, steel arch frames, and concrete covering the anchor bolts and steel arch frames. Among these, the steel arch frames directly bear the pressure of the surrounding rock and the load transferred from the pre-support, controlling the convergence deformation of the surrounding rock; they form the "skeleton" of the initial support. For ease of transportation, steel arch frames are typically installed using a modern splicing method, often consisting of multiple steel sections connected sequentially in an arch shape via flanges and bolts. Because the continuity of the cross-section at the flange connection is disrupted, stress concentration easily occurs at the flange and bolt points during load transfer. Especially when the welding quality between the flange and the steel section is poor, or the bolt preload is insufficient, it can easily lead to localized bending of the flange or uneven stress on the bolts, thus causing deformation. Utility Model Content

[0005] The main purpose of this utility model is to provide a support structure for tunnels traversing fault fracture zones, so as to solve the technical problem of easy deformation at the connection of steel arch frames in the prior art.

[0006] The support structure for a tunnel traversing a fault fracture zone includes steel arch frames arranged at intervals along the route. Each steel arch frame is formed by multiple steel sections connected sequentially to form an arch shape via flanges and bolts. The support structure also includes longitudinal beams connecting adjacent steel arch frames and arranged at intervals along the radial direction of the route, as well as connectors connecting adjacent longitudinal beams. The longitudinal beams include: longitudinal rods placed above, below, to the left, and to the right of the flanges; and stirrups that fix the four longitudinal rods placed above, below, to the left, and to the right of the flanges together radially along the route. The stirrups are arranged at intervals along the route.

[0007] In the support structure of this utility model, firstly, the flange connections of the steel arch frame are reinforced by longitudinal beams; secondly, the flange connections of adjacent steel arch frames are connected as a whole; and thirdly, longitudinal beams at different heights are connected as a whole, ultimately forming a mesh reinforcement structure, which effectively improves the strength of the flange connections and reduces deformation. Because the strength of the support structure is improved, the thickness of the secondary lining concrete can be appropriately reduced, thereby saving material costs and shortening the construction period.

[0008] As a further improvement to the aforementioned support structure for tunnels traversing fault fracture zones: the longitudinal rods are steel bars or steel pipes, with the outer diameter of the steel bars being 15-25 mm and the outer diameter of the steel pipes being 20-40 mm.

[0009] As a further improvement to the aforementioned support structure for tunnels traversing fault fracture zones: the spacing of the stirrups along the route is 200–500 mm.

[0010] As a further improvement to the aforementioned tunnel support structure traversing fault fracture zones, the connecting members are diagonally staggered tie rods. This enhances the reinforcement effect.

[0011] As a further improvement to the aforementioned support structure for tunnels traversing fault fracture zones, the support structure also includes anchor bolts positioned between adjacent steel arches. Each anchor bolt comprises an embedded section inserted into the surrounding rock and a connecting section exposed in the surrounding rock, the connecting section being connected to connectors. Preferably, the connecting section is fixed to two adjacent connectors using butterfly fasteners and nuts. This avoids welding operations and improves construction safety.

[0012] As a further improvement to the aforementioned support structure for tunnels traversing fault fracture zones, the support structure further includes a first concrete layer, a waterproof layer, and a second concrete layer sequentially disposed on the surface of the surrounding rock. The second concrete layer covers the steel arch frame and longitudinal beams, and a reinforcing mesh is filled inside the second concrete layer, with the reinforcing mesh located on the outside of the steel arch frame. Preferably, the reinforcing mesh is tied and fixed integrally with the longitudinal beams. Traditionally, after the anchor bolts are installed, their exposed ends are welded and fixed to the reinforcing mesh, and then the reinforcing mesh is welded to the flanges or webs of the steel arch frame. However, welding operations inside the tunnel pose significant risks. This invention, however, ties the reinforcing mesh and longitudinal beams integrally, and fixes the connecting sections of the anchor bolts to two adjacent connecting parts using butterfly fasteners and nuts, thereby connecting the anchor bolts, reinforcing mesh, and steel arch frame into a single unit, reducing welding operations and significantly improving tunnel operation safety.

[0013] As a further improvement to the aforementioned support structure for tunnels traversing fault fracture zones, the support structure further includes an elastic layer and a third concrete layer sequentially disposed on the surface of the second concrete layer. The elastic layer is either an asphalt layer or a rubber layer. The elastic layer not only effectively improves the resistance to slippage and vibration reduction but also possesses a certain degree of waterproofing. Together with the waterproof layer, it forms a dual waterproofing function, effectively preventing moisture from the surrounding rock from seeping into the tunnel.

[0014] It is evident that the support structure for tunnels traversing fault fracture zones of this utility model is simple and novel, easy to construct, and low in cost. It can effectively improve the strength of flange connections and solve the technical problem of easy deformation at steel arch frame connections in the prior art. It has strong practicality and is very suitable for supporting tunnels traversing fault fracture zones.

[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Additional aspects and advantages of the present invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. Attached Figure Description

[0016] The accompanying drawings, which form part of this utility model, are used to aid in understanding this utility model. The content provided in the drawings and the related descriptions in this utility model can be used to explain this utility model, but do not constitute an undue limitation of this utility model. In the drawings:

[0017] Figure 1 This is a schematic cross-sectional view of the longitudinal beam in the tunnel support structure for traversing a fault fracture zone according to this utility model.

[0018] Figure 2 This is an enlarged cross-sectional view of the longitudinal beam in the tunnel support structure for traversing a fault fracture zone according to this utility model.

[0019] Figure 3This is a front view schematic diagram of the longitudinal beams and connectors in the tunnel support structure for traversing fault fracture zones according to this utility model.

[0020] Figure 4 This is a partial cross-sectional schematic diagram of the tunnel support structure for crossing fault fracture zones according to this utility model.

[0021] The relevant markings in the above figures are:

[0022] 100-Steel arch frame, 110-Structured steel, 120-Flange, 130-Bolt, 200-Longitudinal beam, 210-Longitudinal bar, 220-Stirrup, 300-Connector, 400-Anchor bolt, 410-Butterfly fastener, 510-First concrete layer, 520-Waterproof layer, 530-Second concrete layer, 540-Steel mesh, 550-Elastic layer, 560-Third concrete layer. Detailed Implementation

[0023] The present invention will now be clearly and completely described in conjunction with the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0024] The technical solutions and features provided in the various parts of this utility model, including the following description, can be combined with each other without conflict.

[0025] Furthermore, the embodiments of the present invention described below are generally only a part of the embodiments of the present invention, and not all of the embodiments. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the protection scope of the present invention.

[0026] Regarding the terminology and units used in this utility model: The terms "comprising," "having," and any variations thereof in the specification, claims, and related parts of this utility model are intended to cover non-exclusive inclusion.

[0027] Figure 1 This is a schematic cross-sectional view of the longitudinal beam in the tunnel support structure for traversing a fault fracture zone according to this utility model. Figure 2 This is an enlarged cross-sectional view of the longitudinal beam in the tunnel support structure for traversing a fault fracture zone according to this utility model. Figure 3 This is a front view schematic diagram of the longitudinal beams and connectors in the tunnel support structure for traversing fault fracture zones according to this utility model. Figure 4 This is a partial cross-sectional schematic diagram of the tunnel support structure for crossing fault fracture zones according to this utility model.

[0028] like Figure 1-4The tunnel support structure shown includes steel arch frames 100 arranged at intervals along the route, anchor bolts 400 installed between adjacent steel arch frames 100, and a first concrete layer 510, a waterproof layer 520, a second concrete layer 530, an elastic layer 550, and a third concrete layer 560 sequentially installed on the surrounding rock surface. Each steel arch frame 100 is formed by multiple steel sections 110 connected in sequence to form an arch shape via flanges 120 and bolts 130. The steel sections 110 are I-beams or channel steel.

[0029] The support structure also includes longitudinal beams 200 connecting adjacent steel arch frames 100 and arranged radially at intervals along the line, and connectors 300 connecting adjacent longitudinal beams 200. Each longitudinal beam 200 includes longitudinal bars 210 and stirrups 220. The longitudinal bars 210 are placed above, below, to the left, and to the right of the flange 120. The longitudinal bars 210 are steel bars or steel pipes, with an outer diameter of 15–25 mm for the steel bars and 20–40 mm for the steel pipes. The stirrups 220 fix the four longitudinal bars 210 placed above, below, to the left, and to the right of the flange 120 together radially along the line. The stirrups 220 are arranged at intervals along the line, with a spacing of 200–500 mm. The connectors 300 are diagonally staggered tie bars.

[0030] The anchor bolt 400 includes an embedded section inserted into the surrounding rock of the tunnel and a connecting section exposed in the surrounding rock of the tunnel. The connecting section is fixed to two adjacent connecting members 300 by a butterfly fastener 410 and a nut. The number of connecting members 300, the degree of inclination, and the longitudinal rod 210 connected to them can be adjusted and selected according to the position of the anchor bolt 400.

[0031] The second concrete layer 530 covers the steel arch frame 100 and the longitudinal beam 200. The interior of the second concrete layer 530 is filled with a steel mesh 540, which is located on the outside of the steel arch frame 100 and is tied and fixed to the longitudinal beam 200 as a whole.

[0032] The elastic layer 550 is an asphalt layer or a rubber layer. The third concrete layer 560 can be plain concrete or reinforced with steel bars as needed for the project.

[0033] The construction sequence is as follows: After the pre-support structure (such as pipe roof and small guide pipe) is completed, the tunnel is excavated. Then, on the surface of the surrounding rock, the first concrete layer 510 (strength C20~C25, thickness 3~5cm), anchor bolts 400 (grouting is required after insertion), waterproof layer 520, steel mesh 540, steel arch frame 100, longitudinal beam 200, connector 300, and the second concrete layer 530 (strength C20~C25, thickness exceeding the steel arch frame 100 by 5~10cm) are applied, which completes the initial support construction. After the deformation is basically stable, the elastic layer 550 and the third concrete layer 560 (strength C30~C40, thickness 20~40cm) are applied, which completes the secondary lining construction.

[0034] The foregoing has described the relevant content of this utility model. Those skilled in the art will be able to implement this utility model based on these descriptions. All other embodiments obtained by those skilled in the art based on the above description of this utility model without inventive effort should fall within the protection scope of this utility model.

Claims

1. A tunnel support structure crossing a fault fracture zone, comprising steel arches (100) arranged at intervals along the route direction, each steel arch (100) being connected in sequence into an arch shape by a plurality of section steels (110) through flanges (120) and bolts (130), characterized in that: The support structure also includes longitudinal beams (200) that connect adjacent steel arch frames (100) and are arranged at radial intervals along the line, and connectors (300) that connect adjacent longitudinal beams (200); the longitudinal beams (200) include: Longitudinal rod (210), the longitudinal rod (210) is placed above, below, left and right of flange (120); The stirrups (220) fix the four longitudinal rods (210) placed on the flange (120) radially along the line to one piece; the stirrups (220) are arranged at intervals along the line.

2. The fault fracture zone tunnel support structure of claim 1, wherein: The longitudinal bar (210) is a steel bar or a steel pipe, with the outer diameter of the steel bar being 15-25 mm and the outer diameter of the steel pipe being 20-40 mm.

3. The fault fracture zone tunnel support structure of claim 1, wherein: The spacing of the stirrups (220) along the route is 200-500mm.

4. The fault fracture zone tunnel support structure of claim 1, wherein: The connector (300) is a tie rod arranged diagonally and intersectingly.

5. The tunnel support structure for traversing a fault fracture zone as described in claim 1, characterized in that: The support structure also includes anchor bolts (400) disposed between adjacent steel arch frames (100), the anchor bolts (400) including an embedded section inserted into the surrounding rock of the tunnel and a connecting section exposed in the surrounding rock of the tunnel, the connecting section being connected to a connector (300).

6. The fault fracture zone tunnel support structure of claim 5, wherein: The connecting section is secured to two adjacent connecting parts (300) by a butterfly fastener (410) and a nut.

7. The fault fracture zone tunnel support structure of Claim 1, wherein: The support structure also includes a first concrete layer (510), a waterproof layer (520), and a second concrete layer (530) sequentially disposed on the surface of the surrounding rock. The second concrete layer (530) covers the steel arch frame (100) and the longitudinal beam (200). The interior of the second concrete layer (530) is filled with a steel mesh (540), which is disposed on the outside of the steel arch frame (100).

8. The fault fracture zone tunnel support structure of claim 7, wherein: The steel mesh (540) is tied and fixed to the longitudinal beam (200) as a whole.

9. The fault fracture zone tunnel support structure of claim 7, wherein: The support structure also includes an elastic layer (550) and a third concrete layer (560) sequentially disposed on the surface of the second concrete layer (530), wherein the elastic layer (550) is an asphalt layer or a rubber layer.

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