Extrusion stratum windowing stress release supporting structure
By setting stress relief windows and flexible mesh in the tunnel, horizontal deformation of the rock and soil mass is allowed. Combined with components such as steel mesh and steel arch frame, the problem of tunnel compression deformation under high ground stress is solved, thereby improving safety and reliability while reducing construction costs.
Patent Information
- Application Number
- CN202423196403.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2025-12-02
- Estimated Expiration
- 2034-12-24
AI Technical Summary
Under high ground stress conditions, after the excavation of soft rock tunnels, the surrounding rock shifts into the clearance, causing the compression deformation to exceed the normal range, resulting in phenomena such as support twisting failure and secondary lining cracking. Existing reinforcement support measures are costly and have limited effectiveness.
Design a stress-relief support structure with extrusion-type strata opening, including a primary lining and a secondary lining, setting stress relief windows and flexible mesh to allow horizontal deformation of the soil and rock mass, reducing the load on the support structure through stress relief, and using components such as steel mesh, steel arch frame, system anchors and locking foot anchors for support.
It effectively limits the vertical deformation of the soil and rock mass, reduces the load on the support structure, improves the safety and reliability of tunnel construction, ensures the strength of the support structure, avoids the risk of rock bursts and collapses, and reduces construction costs.
Smart Images
Figure CN223621615U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of tunnel support technology, specifically relating to a stress relief support structure for compressive strata with window opening. Background Technology
[0002] Under high ground stress conditions, after the excavation of a soft rock tunnel, the surrounding rock displaces into the clearance, compressing the support system. This displacement exceeds the normal deformation of the surrounding rock, i.e., the allowable deformation, and is called compressive deformation. The stratum where the tunnel is located is called a compressive stratum. Tunnels constructed in compressive strata experience large compressive deformation during construction, resulting in phenomena such as support twisting failure, encroachment, and secondary lining cracking.
[0003] Currently, the measures taken to address tunnel compression deformation and failure typically involve strengthening the support, such as reducing the spacing between arch frames, increasing the density of the steel reinforcement mesh, and increasing the lining thickness. However, these strengthening support measures are costly and may not necessarily achieve good support results. Utility Model Content
[0004] The purpose of this invention is to provide a stress-relieving support structure with a squeeze-type stratum opening, which reduces the load borne by the support structure by restricting the vertical deformation of the rock and soil mass while allowing appropriate horizontal deformation, thereby improving the safety and reliability of tunnel construction.
[0005] This utility model adopts the following technical solution: a compressional stratum window stress relief support structure, which includes a primary lining layer and a secondary lining layer from the outside to the inside, wherein the side attached to the rock and soil mass is the outside;
[0006] Each initial lining layer consists of a steel mesh and multiple steel arches, arranged from the outside in. The steel mesh covers the tunnel walls, and four stress relief windows are formed around its circumference. Two of these windows are located at the center of the left and right sides of the upper bench excavation section, while the other two are located at the sidewalls of the lower bench excavation section. These stress relief windows serve as outlets for the extrusion of soil and rock masses under tunnel stress deformation. After the soil and rock masses have stabilized, the steel mesh is reformed at the stress relief windows.
[0007] Furthermore, the four stress relief windows are located between two adjacent steel arch frames, and the centers of the four stress relief windows are located on the same circumferential tangential plane of the tunnel.
[0008] Furthermore, each stress relief window is a rectangle or a square, with a length and width of 50~100cm.
[0009] Furthermore, each steel arch frame is either arc-shaped or arched, encircling the tunnel wall, with multiple steel arch frames arranged at intervals along the longitudinal direction of the tunnel.
[0010] Furthermore, at each stress relief window location, and attached to the tunnel wall, a flexible mesh is installed to support small fragments of rock and soil; this mesh is then removed after the surrounding rock deformation has stabilized.
[0011] Furthermore, the flexible mesh for the window includes a flexible mesh body and supporting ropes, which are consistent with the shape of the stress-relief window;
[0012] The support rope consists of multiple ropes that form a grid-like frame. The outer frame of the grid-like frame wraps around the outer edge of the flexible mesh body of the window and is connected to the outer edge to support the flexible mesh body of the open window.
[0013] Anchors perpendicular to the four corners and center of the flexible mesh body are set. The anchors include threaded steel bars and nuts. One end of the threaded steel bar is inserted into the soil and rock, and the other end passes through the mesh at its location. A nut is screwed onto the end of the threaded steel bar and between the nut and the flexible mesh body. A washer is also fitted on the threaded steel bar and between the nut and the flexible mesh body. By tightening the nut, the flexible mesh body is pressed onto the soil and rock and is tightened and fixed.
[0014] Furthermore, multiple system anchor bolts are installed at intervals around the circumference outside the tunnel, with the multiple system anchor bolts arranged at intervals in both the circumferential and longitudinal directions;
[0015] One end of each system anchor is welded to the steel mesh, and the other end passes through the initial lining and is inserted into the soil and rock mass, extending through the soil and rock mass to the outside of the tunnel.
[0016] Furthermore, multiple anchor bolts are installed at intervals at the left and right arch feet of the tunnel. Each anchor bolt is installed at intervals, with one end welded to the steel arch frame and the other end penetrating through the initial lining and inserting into the rock and soil mass, extending through the rock and soil mass to the outside of the tunnel.
[0017] The beneficial effects of this utility model are: 1. By setting a stress relief window, the rock and soil mass is allowed to deform under pressure. After the deformation of the rock and soil mass stabilizes and the stress is fully released, the stress relief window is closed. By limiting the vertical deformation of the rock and soil mass, appropriate horizontal deformation is allowed, reducing the load borne by the support structure and thus improving the safety of tunnel construction. 2. After the deformation of the rock and soil mass stabilizes, a reinforcing mesh is formed at the stress relief window to ensure the strength of the support structure and guarantee the safety of the tunnel. 3. A detachable flexible mesh is set up at the window to support the crushed stone, preventing accidents. Attached Figure Description
[0018] Figure 1 A schematic cross-section of a stress-relieving support structure for extrusive formation windows;
[0019] Figure 2 This is a detailed view of a portion of the initial lining layer;
[0020] Figure 3A schematic diagram of a flexible mesh window;
[0021] Figure 4 This is a diagram showing the initial lining reinforcement layout;
[0022] Among them: 1. System anchor bolts; 2. Locking foot anchor bolts; 3. Primary lining layer; 31. Shotcrete; 32. Steel arch frame; 33. Window flexible mesh; 331. Support rope; 332. Stitching rope; 333. Anchor nails; 34. Reinforcing mesh; 4. Secondary lining layer; 35. Stress relief window. Detailed Implementation
[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0024] This utility model discloses a stress-relieving support structure for compressive strata opening, suitable for bench tunnel excavation, such as... Figure 1 , 2 As shown in Figure 3, from the outside to the inside, it includes a primary lining layer 3 and a secondary lining layer 4, wherein the side attached to the rock and soil mass is the outside; the primary lining layer 3 includes, from the outside to the inside, a steel mesh 34, a window flexible mesh 33, a steel arch frame 32 and shotcrete 31.
[0025] A reinforcing mesh 34 covers the tunnel wall and is laid in segments, with each segment typically 3 meters long longitudinally. It consists of intersecting circumferential and longitudinal reinforcing bars spaced 10-20 cm apart. Four stress relief windows 35 are provided around the circumference of the mesh 34. Two of these windows are located at the center of the left and right sides of the upper bench excavation section, while the other two are located at the sidewalls of the lower bench excavation section. These stress relief windows 35 serve as outlets for the extrusion of soil and rock masses under tunnel stress deformation. After the soil and rock masses stabilize, the reinforcing mesh is reformed at the stress relief windows 35 to ensure the strength of the support structure.
[0026] The stress relief windows 35 are 50-100cm in length and width. Two stress relief windows 35 are located at the center of the left and right sides of the upper bench excavation section of the tunnel, allowing the soil and rock mass to be squeezed out of the windows; the other two stress relief windows 35 are located at the sidewalls; the four stress relief windows 35 serve as extrusion outlets for the soil and rock mass deformed by tunnel stress. For the soil and rock mass itself, energy is fully released, reducing the risk of rock bursts and collapses.
[0027] At each stress relief window 35, a flexible mesh 33 is attached to the tunnel wall and covered to catch small pieces of rock and soil, preventing them from falling and injuring people.
[0028] Four stress relief windows 35 are located between two adjacent steel arch frames 32, and the centers of the four stress relief windows 35 are located on the same circumferential tangential plane of the tunnel. No shotcrete is applied at the stress relief window locations initially, and the soil and rock mass is squeezed out and deformed towards the window. After the deformation stabilizes, the flexible mesh 33 of the window is removed, the squeezed soil and rock mass is cleared, the steel mesh 34 is replaced, and the window is sealed with shotcrete 31.
[0029] The steel arch frame 32 consists of multiple sections, each of which is either arc-shaped or arched and encircles the tunnel wall. The multiple steel arch frames 32 are arranged at intervals along the longitudinal direction of the tunnel, with the distance between two adjacent steel arch frames 32 being 80~150cm.
[0030] The secondary lining layer 4 includes a reinforcing cage, which is circumferentially attached to the primary lining layer 3 and then cast in concrete. A waterproof membrane is installed between the secondary lining layer and the primary lining layer.
[0031] Multiple system anchors 1 are installed at intervals around the circumference of the tunnel. These anchors 1 are spaced apart both circumferentially and longitudinally. One end of each anchor 1 is inserted into and passes through the soil and rock layer, and welded to the reinforcing mesh 34. The other end is located outside the tunnel. When the position of an anchor 1 coincides with the position of a stress relief window 35, the anchor 1 positions are staggered, with a distance greater than 50cm between the anchor 1 and the stress relief window. The reinforcing mesh at the window needs to be restored to ensure that its strength is not affected.
[0032] Locking anchor rods 2 are installed on both the left and right sides outside the tunnel. There are multiple locking anchor rods 2. One end of each locking anchor rod 2 is inserted into and passes through the rock and soil layer and welded to the steel arch frame 32.
[0033] like Figure 4 As shown, the flexible mesh 33 prevents brittle rock from splashing out. It includes a flexible mesh body and support ropes 331. The flexible mesh body is rectangular or square, matching the shape of the stress relief window 35. The flexible mesh body is a net formed by interlaced stitching ropes 332, with a diamond-shaped mesh. The stitching ropes 332 are made of φ8 low-carbon steel strand.
[0034] Multiple support ropes 331 are arranged to form a grid-like frame. The outer frame of the grid-like frame wraps around the outer edge of the flexible window mesh body and connects to the outer edge. The center of the inner cross frame of the grid-like frame coincides with the center of the flexible window mesh body, dividing the flexible window mesh body into four sections. The support ropes 331 are made of φ12 low-carbon steel stranded wire and are used to support the flexible window mesh body when it is open.
[0035] Anchors 333, perpendicular to the four corners and center of the flexible mesh body, are provided. Anchors 333 include threaded steel bars and nuts. One end of the threaded steel bar is inserted into the soil and rock, and the other end passes through the mesh at its location. A nut is screwed onto the end of the threaded steel bar and between the nut and the flexible mesh body. By tightening the nut, the flexible mesh body is pressed onto the surface of the soil and rock, and thus tightened and fixed.
[0036] The construction method of the above-mentioned stress relief support structure for compressive strata is as follows:
[0037] Step S1, Drilling: Drill holes in the excavated tunnel wall, including drilling holes for anchor bolts 2, system anchor bolts 1, and anchor nails 333.
[0038] Step S2, Install steel mesh 34: Weld steel mesh 34 to the arch foot.
[0039] Step S3: Install steel arch frames: Install multiple steel arch frames 32 around the inner wall of the tunnel in a circumferential manner. The multiple steel arch frames 32 are arranged at intervals along the longitudinal direction of the tunnel.
[0040] Step S4: Install system anchor 1 and weld system anchor 1 to steel mesh 34.
[0041] Step S5: Install the flexible window mesh 33: Place the flexible window mesh body tightly against the rock and soil wall and insert anchor nails 333 for fixation.
[0042] Step S6: Except for the location of the flexible mesh 33 at the window, sprayed concrete 31 is applied inside the tunnel to cover the surface of the rock and soil.
[0043] Step S7: After the deformation of the rock and soil mass stabilizes, remove the flexible mesh 33 of the window, clear away the extruded rock and soil mass, and construct shotcrete to seal the window at the position of the flexible mesh 33.
[0044] Step S8: Install the secondary lining steel cage circumferentially on the primary lining layer 3, and pour the secondary lining concrete to complete the secondary lining layer 4 structure.
Claims
1. A stress-relieving support structure for extruded formations with window openings, characterized in that, From the outside to the inside, it includes the initial lining layer (3) and the second lining layer (4), wherein the side attached to the rock and soil mass is the outside; Each section of the initial lining (3) includes, from the outside to the inside, a steel mesh (34) and multiple steel arch frames (32). The steel mesh (34) covers the tunnel wall. The steel mesh (34) has four stress relief windows (35) around its circumference. Two of the stress relief windows (35) are located at the center of the left and right sides of the upper bench excavation section of the tunnel. The other two stress relief windows (35) are located at the sidewalls of the left and right sides of the lower bench excavation section of the tunnel. The stress relief windows (35) are used as extrusion outlets for the rock and soil mass that is deformed by the stress in the tunnel. After the deformation of the soil and rock mass stabilizes, a reinforcing mesh (34) is re-formed at the stress relief window (35).
2. The compressional stratum window-opening stress relief support structure as described in claim 1, characterized in that, The four stress relief windows (35) are located between two adjacent steel arch frames (32), and the centers of the four stress relief windows (35) are located on the same circumferential tangential plane of the tunnel.
3. The compressional stratum window-opening stress relief support structure as described in claim 2, characterized in that, Each stress relief window (35) is rectangular or square, with a length and width of 50 to 100 cm.
4. The compressional stratum window-opening stress relief support structure as described in claim 3, characterized in that, Each of the steel arch frames (32) is arc-shaped or arch-shaped and surrounds the tunnel wall. The steel arch frames (32) are arranged at intervals along the longitudinal direction of the tunnel.
5. The compressional stratum window-opening stress relief support structure as described in claim 4, characterized in that, At each stress relief window (35) location, and attached to the tunnel wall, a flexible mesh (33) is provided to support small fragments of rock and soil; and it is removed after the surrounding rock deformation stabilizes.
6. The compressional stratum window-opening stress relief support structure as described in claim 5, characterized in that, The flexible mesh (33) of the window includes a flexible mesh body and a support rope (331), which is consistent with the shape of the stress relief window (35); The support rope (331) consists of multiple ropes, which together form a grid frame. The outer frame of the grid frame wraps around the outer edge of the flexible mesh body of the window and is connected to the outer edge to support the flexible mesh body of the open window. Anchors (333) perpendicular to the four corners and center of the flexible mesh body of the window are provided. The anchors (333) include threaded steel bars and nuts. One end of the threaded steel bar is used to insert into the rock and soil, and the other end passes through the mesh at its location and is screwed with a nut. A washer is also provided on the threaded steel bar and between the nut and the flexible mesh body of the window. By tightening the nut, the flexible mesh body of the window is pressed onto the rock and soil and is tightened and fixed.
7. The compressional stratum window-opening stress relief support structure as described in claim 6, characterized in that, Multiple system anchors (1) are installed at intervals around the outside of the tunnel in a circumferential direction, and the multiple system anchors (1) are arranged at intervals in both the circumferential and longitudinal directions; One end of each of the system anchors (1) is welded to the steel mesh (34), and the other end passes through the initial lining (3) and is inserted into the soil and rock mass, extending through the soil and rock mass to the outside of the tunnel.
8. The compressional stratum window-opening stress relief support structure as described in claim 7, characterized in that, Multiple anchor rods (2) are installed at intervals at the left and right arch feet of the tunnel. Each anchor rod (2) is installed at intervals, with one end welded to the steel arch frame (32) and the other end inserted into the rock and soil through the initial lining layer (3) and extending through the rock and soil to the outside of the tunnel.