A high-stress and large-deformation roadway support system and method

Abstract

The present invention discloses a high-stress and large-deformation tunnel support system and method, which relates to the technical field of tunnel support. The steel shell support is arranged close to the inner wall of the tunnel, and the anchor cable is installed on the steel shell support to fix it on the inner wall of the tunnel; the anchor cables and anchor rods are installed at intervals on the two sides and arch of the soft rock tunnel, and a metal mesh is laid on the anchor cables and anchor rods for hanging and fixing; a retractable metal support is installed on one side of the metal mesh, and the retractable metal support legs are supported by double rows of anchor piles; concrete is poured through the grouting holes to make the flexible concrete spray layer cover the gap formed by the metal mesh, the retractable metal support, the steel shell support, and the inner wall of the tunnel. The above-mentioned support method and system can not only effectively improve the stability and support strength of the surrounding rock of the high-stress and large-deformation soft rock tunnel, but also has the advantages of safety and reliability, low construction cost, and easy to promote on a large scale. It can greatly improve the stability of the soft rock tunnel and realize tunnel support.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel support, and in particular to a high-stress and large-deformation tunnel support system and method. Background Art

[0002] In recent years, with the development of the coal industry and the increase in excavation depth, the surrounding rock pressure on the tunnel surrounding rock and support has also increased. The large deformation of the tunnel caused by high stress has aggravated the difficulty of supporting soft rock tunnels. Soft rock tunnel support has become a key and difficult problem that needs to be solved urgently in current mining and underground engineering. As the burial depth increases, the ground stress gradually increases. When the tunnel position reaches a certain depth, the weight of the overlying rock strata will cause the tunnel surrounding rock to be under high stress level. Soft rock lithology is mostly water-permeable clay minerals. When they come into contact with water, they easily undergo physical or chemical changes, reducing the anti-sliding strength of the rock mass and ultimately leading to a decrease in the strength of the surrounding rock. Deep tunnels are usually affected by repeated mining in the chamber. The stress environment is complex and mostly in a high-stress state. After the tunnel is excavated, the structural stress of the bearing body and the geological tectonic stress are superimposed, resulting in a significant stress concentration state, which accelerates the overall deformation of the surrounding rock tunnel.

[0003] The geological environment of the rock mass significantly influences the mechanical properties of the surrounding rock at depth. With the increasing deformation of soft rock roadway support, traditional support methods have become increasingly inadequate in recent years to maintain stability in these tunnels. Generally speaking, the self-stabilization time of soft rock roadways is very short. Without artificial support measures after tunnel excavation, surrounding rock instability and deformation can easily occur. Since the bearing capacity of a roadway is relatively weak during initial excavation, support measures are necessary to protect the surrounding rock mass, maintain overall stability, and minimize deformation and damage. Due to the large deformation and strong low-pressure characteristics of deep roadways, traditional rigid support methods commonly used in shallower roadways are unsuitable for highly stressed soft rock. If rigid support methods are used, the support structure will be damaged when roadway pressure is applied, making it impossible to ensure roadway support stability. The degree and rate of deformation of the surrounding rock in the roadway increase, leading to phenomena such as broken anchor bolts and cables, slippage of nuts, roof tearing, and localized collapse. Since the surrounding rocks of soft rock tunnels contain mostly clay minerals, they will soften due to expansion once they come into contact with water. The two sides of rock will bulge out and squeeze into the tunnel, eventually becoming loose and broken.

[0004] Although many experts and scholars at home and abroad have proposed many solutions for supporting high-stress soft rock roadways, which have suppressed large deformations of the surrounding rock to a certain extent, they have not achieved a good support effect. The support structure is often damaged and deformed significantly within a short period of time, which in turn leads to permanent failure of the support structure, affecting the safe construction and passage of the roadway. Therefore, there is an urgent need to develop a support method that can not only effectively improve the stability and support strength of the surrounding rock of high-stress soft rock roadways, but also be safe, reliable, low-cost, and easy to promote on a large scale. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-stress and large-deformation tunnel support system and method to solve the problem that traditional support methods are poor in effect and prone to failure in high-stress and large-deformation tunnels.

[0006] To solve the above technical problems, the present invention adopts the following technical solution: a high stress and large deformation roadway support method, characterized by comprising the following steps:

[0007] S1. Arrange the steel shell support close to the inner wall of the tunnel, install anchor cables on the steel shell support, and fix it to the inner wall of the tunnel;

[0008] S2. Install anchor cables and bolts at intervals along the sides and arch of the soft rock tunnel, and lay metal mesh on the anchor cables and bolts to secure them.

[0009] S3. Install a retractable metal bracket on one side of the metal mesh, with the legs of the retractable metal bracket supported by double rows of anchor piles.

[0010] S4. Pour concrete through the grouting holes so that the flexible concrete spray layer covers the gaps formed by the metal mesh, the retractable metal support, the steel shell support, and the inner wall of the tunnel.

[0011] A further technical solution is that the steel shell support includes a number of grid units arranged in parallel along the length of the tunnel, using The spacing between adjacent truss units is 600mm to 800mm.

[0012] A further technical solution is that the anchor rod specification is Anchor rod spacing is 1600mm, row spacing is 1600mm; anchor cable specifications are The spacing between anchor cables is 1600mm~2400mm, and the row spacing is 1600mm~2400mm.

[0013] A further technical solution is that the length×width of the metal mesh is 5000mm×2000mm, and the mesh size is 80mm×80mm.

[0014] A further technical solution is that the proportion of the raw materials in the concrete is cement: water: sand = 1: 0.4: 1.4, and the thickness of the flexible concrete spray layer is 400 mm.

[0015] A further technical solution is that the retractable metal bracket is an arched bracket made of U-shaped steel.

[0016] A further technical solution is that the support system includes a steel shell support, a flexible concrete sprayed layer, a metal mesh and a retractable metal support arranged in sequence from the outside to the inside. The steel shell support is fixed to the inner wall of the tunnel by anchor cables and anchor rods. Metal mesh is hung on the ends of the anchor cables and anchor rods. A retractable metal support is arranged on the inside of the metal mesh. The legs of the retractable metal support are supported by double rows of anchor piles. The flexible concrete sprayed layer is covered in the gap formed by the metal mesh, the retractable metal support, the steel shell support and the inner wall of the tunnel.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The outer stress-bearing arch is formed by reinforced shell supports and a flexible concrete spray layer. Anchor cables and anchor rods form an extrusion reinforcement arch. Retractable metal supports and double rows of anchor piles form an inner stress-bearing arch. This supports the structure from the outside in, significantly improving the mechanical properties and self-supporting capacity of the deep soft rock mass. This provides a reliable foundation for the installation, tensioning, and anchoring of the anchor cables in subsequent steps. Furthermore, this structure is a semi-rigid support structure, offering the advantages of flexible support (allowing for some deformation) and the superior effectiveness of rigid support.

[0019] 2. Anchor rods and anchor cables are densely installed in the shallow rock layer of the surrounding rock and arranged at a certain interval. The compressive stresses formed in the rock mass around each anchor rod overlap with each other to form a uniform, thicker and stronger compression zone.

[0020] 3. The retractable metal support is an arched support made of U-shaped steel, adapted to the cross-sectional dimensions of the roadway. It is used to further support the soft rock roadway. At the same time, double rows of anchor piles are used to support the key legs. The double rows of anchor piles fix the retractable metal support with hinged supports, preventing the legs from shifting inward. This reduces horizontal forces while increasing the tensile strength of the anchor rods, enhancing the overall bearing capacity of the support structure and effectively reducing surrounding rock deformation.

[0021] 4. The continuous advancement of the working face and the segmented arrangement of steel shell supports and retractable metal supports can greatly improve the support effect of soft rock tunnels, reduce the anchor loss rate, and thus ensure safe operation of workers underground.

[0022] 5. The above-mentioned support method and system can not only effectively improve the stability and support strength of the surrounding rock of high-stress and large-deformation soft rock tunnels, but also have the advantages of safety and reliability, low construction cost, and easy large-scale promotion. It can greatly improve the stability of soft rock tunnels and realize tunnel support. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a cross-sectional schematic diagram of the present invention.

[0024] Figure 2It is a plan schematic diagram along the direction of the lane of the present invention.

[0025] In the figure: 1-rebar shell support, 2-anchor cable, 3-anchor rod, 4-metal mesh, 5-retractable metal support, 6-flexible concrete spray layer. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0027] Example

[0028] A high-stress and large-deformation roadway support method comprises the following steps:

[0029] S1. The steel shell support 1 is arranged close to the inner wall of the tunnel, and the anchor cable 2 is installed on the steel shell support 1 to fix it to the inner wall of the tunnel;

[0030] S2. Anchor cables 2 and anchor rods 3 are installed at intervals on both sides of the soft rock tunnel and the arch, and metal mesh 4 is laid at the ends of the anchor cables 2 and anchor rods 3 to be fixed by hanging the mesh;

[0031] S3. The metal mesh 4 is installed on one side of the retractable metal bracket 5, the retractable metal bracket 5 legs are supported by double rows of anchor piles;

[0032] S4. Pour concrete through the grouting holes so that the flexible concrete spray layer 6 covers the gap formed by the metal mesh 4, the retractable metal support 5 and the steel shell support 1, and the inner wall of the tunnel.

[0033] like Figure 1 As shown, the support system includes a steel shell support 1, a flexible concrete spray layer 6, a metal mesh 4 and a retractable metal support 5 arranged in sequence from the outside to the inside. The steel shell support 1 is fixed to the inner wall of the tunnel by anchor cables 2 and anchor rods 3. Metal mesh 4 is hung at the ends of the anchor cables 2 and anchor rods 3. Retractable metal support 5 is arranged on the inside of the metal mesh 4. The legs of the retractable metal support 5 are supported by double rows of anchor piles. The flexible concrete spray layer 6 covers the gap formed by the metal mesh 4, the retractable metal support 5, the steel shell support 1 and the inner wall of the tunnel.

[0034] The steel shell support 1 and the flexible concrete sprayed layer 6 constitute the outer circle stress-bearing arch with a total thickness of 2m; the anchor cable 2 and the anchor rod 3 constitute the extrusion reinforcement arch with a total thickness of 2.5m; the retractable metal support and the double row of anchor piles constitute the inner circle stress-bearing arch with a thickness of 0.3m. The cross-section adopts a straight wall semi-circular arch section. The specifications after the top is raised, the sides are opened, and the bottom is laid are width × height = 4000mm × 3000mm.

[0035] The steel shell support 1 comprises a number of grid units arranged in parallel along the length direction of the tunnel. The reinforcement is arranged with spacing of 0.6-0.8m between adjacent grid units. The flexible concrete spray layer 6 has a raw material mix ratio of cement: water: sand = 1:0.4:1.4, providing excellent toughness and ensuring that the steel shell support 1 will not break even if deformed. After the outer ring stress-bearing arch is completed, tunnel excavation and anchor support 3 are alternated, with each cycle advancing 3.0-5.0m. The steel shell support 1 is then installed within the tunnel.

[0036] The specifications of the anchor rod 3 are Anchor bolt spacing is 1600mm, row spacing is 1600mm; anchor cable 2 specifications are The spacing between anchor cables is 1600mm and the spacing between rows is 1600mm. Figure 2 As shown, the metal mesh 4 has a length×width of 5000 mm×2000 mm and a mesh size of 80 mm×80 mm.

[0037] The retractable metal support 5 is an arched support made of U-shaped steel, which is adapted to the cross-sectional dimensions of the tunnel and is used to further support the soft rock tunnel. At the same time, the legs at key locations are jointly supported with double rows of anchor piles. The segmented arrangement of the retractable metal support 5 during the continuous advancement of the working surface can greatly improve the support effect of the soft rock tunnel, reduce the anchor loss rate, and thus ensure safe operation of workers underground. Specifically, reinforcing the anchor piles on the legs of the retractable metal support 5 is equivalent to fixing the hinged support thereon, which can prevent the legs from moving inward, while reducing the horizontal force, increasing the pull-out resistance of the anchor, enhancing the overall bearing capacity of the support structure, and effectively reducing the deformation of the surrounding rock.

[0038] Although the present invention has been described herein with reference to a number of illustrative embodiments thereof, it will be appreciated that numerous other modifications and implementations may be devised by those skilled in the art, which would fall within the scope and spirit of the present disclosure. More specifically, various variations and modifications may be made to the components or arrangements within the scope of the present disclosure, the drawings, and the claims. In addition to variations and modifications to the components or arrangements, other uses will also be apparent to those skilled in the art.

Claims

1. A high stress and large deformation tunnel support method, characterized in that The steps include: S1. Arrange the steel shell support (1) close to the inner wall of the roadway, install the anchor cable (2) on the steel shell support (1), and fix it to the inner wall of the roadway; S2. Anchor cables (2) and anchor rods (3) are installed at intervals on both sides and the arch of the soft rock tunnel, and a metal mesh (4) is laid on the anchor cables (2) and anchor rods (3) to fix the mesh; S3. A retractable metal bracket (5) is installed on one side of the metal mesh (4). The retractable metal bracket (5) is supported by a double row of anchor piles on the legs; S4. Concrete is poured through the grouting holes to form a flexible concrete spray layer (6) covering the metal mesh (4), the retractable metal bracket (5) and the steel shell bracket (1), and the gap formed by the inner wall of the tunnel; The specifications of the anchor rods (3) are φ20×1800mm, the anchor rod spacing is 1600mm, and the row spacing is 1600mm; The specification of the anchor cable is φ17.8×6000mm, the anchor cable spacing is 1600mm~2400mm, and the row spacing is 1600mm~2400mm; the steel shell support (1) and the flexible concrete spray layer (6) constitute an outer ring stress-bearing arch with a total thickness of 2m; the anchor cable (2) and the anchor rod (3) constitute an extrusion reinforcement arch with a total thickness of 2.5m; the retractable metal support (5) and the double-row anchor piles constitute an inner ring stress-bearing arch with a thickness of 0.3m.

2. A high stress and large deformation roadway support method according to claim 1, characterized in that: The steel bar shell support (1) comprises a plurality of grid units arranged in parallel along the length direction of the tunnel, and is made of φ20-φ40 steel bars, with an interval of 600mm-800mm between adjacent grid units.

3. A high stress and large deformation roadway support method according to claim 1, characterized in that: The metal mesh (4) has a length × width of 5000 mm × 2000 mm, and a mesh size of 80 mm × 80 mm.

4. A high stress and large deformation roadway support method according to claim 1, characterized in that: The proportion of raw materials in the concrete is cement: water: sand = 1: 0.4: 1.4, and the thickness of the flexible concrete spray layer (6) is 0.4m.

5. The high stress and large deformation roadway support method according to claim 1, characterized in that: The retractable metal bracket (5) is an arched bracket made of U-shaped steel.

6. A high stress and large deformation roadway support method according to any one of claims 1 to 5, characterized in that: The support system comprises a steel shell support (1), a flexible concrete spray layer (6), a metal mesh (4) and a retractable metal support (5) which are arranged in sequence from the outside to the inside. The steel shell support (1) is fixed to the inner wall of the tunnel through an anchor cable (2) and an anchor rod (3). The ends of the anchor cable (2) and the anchor rod (3) are hung with a metal mesh (4). The retractable metal support (5) is arranged on the inner side of the metal mesh (4). The legs of the retractable metal support (5) are supported by double-row anchor piles. The flexible concrete spray layer (6) is covered in a gap formed by the metal mesh (4), the retractable metal support (5), the steel shell support (1) and the inner wall of the tunnel.

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