A method for dredging silt in a filling hole in horizontal advance grouting in a limited space

Abstract

The application provides a limited space horizontal advance grouting filling hole siltation material dredging method, which comprises hole siltation material arrangement, buried water diversion pipe, net hanging, C20 concrete spraying, backward grouting, pipe bundle grouting, effect verification and dredging, and the method is a precondition that the initial support of the formed hole section is not damaged or slightly damaged except the position of the sudden gushing. The method drills to the position of the sudden gushing by a drilling machine, carries out backward grouting to stabilize the siltation material in a certain range in the hole, drills to form a hole and installs a small catheter with a slurry overflow hole at the front end to fill and stabilize the siltation material in a certain range in the hole to stabilize the position of the sudden gushing, and the problem of the sudden gushing is avoided in the subsequent process of removing the siltation material in the hole. The method belongs to the field of tunnel construction.

Description

Technical Field

[0001] This invention relates to a method for clearing silt deposits in a confined space by horizontal pre-grouting, which belongs to the field of tunnel construction. Background Technology

[0002] Currently, after a sudden surge occurs in a tunnel, the traditional method involves clearing the silt inside the tunnel until a critical state is reached (i.e., silt creep occurs), installing a grout stop wall (C20 concrete or C20 shotcrete), grouting and reinforcing the silt in sections, clearing silt in sections to a certain distance (approximately 10m) from the surge location, and then performing pre-consolidation grouting on a certain area outside the excavation outline. For tunnel sections where the initial support is undamaged or only slightly damaged, the traditional method of clearing silt inside the tunnel suffers from problems such as a long grouting reinforcement area, multiple grouting sessions, long processing time, and high costs. Summary of the Invention

[0003] This invention provides a method for clearing silt from tunnels by horizontal pre-grouting in a limited space, in order to solve the problem of limited silt removal in tunnel sections where the initial support is not damaged.

[0004] To achieve the above objectives, a method for clearing silt from tunnels using pre-grouting in a confined space is proposed. This method involves first clearing the silt from the branch tunnel and downstream tunnel, then clearing the silt from the upstream tunnel to a critical position and state. The critical position and state refer to the critical position or state where continuing dredging poses a risk of sudden gushing. Afterward, the exposed surface of the silt in the tunnel is prepared, drainage pipes are installed inside the silt to drain accumulated water or seepage from sudden gushing points, and then mesh is hung and shotcrete is applied to the prepared exposed surface of the silt. The silt is then initially stabilized by grouting, and then a hole is drilled to install a Φ42 small guide pipe with an overflow hole for grouting and filling the silt in the tunnel. Finally, the grout stop wall is removed, and the silt in the tunnel is cleared.

[0005] In the aforementioned dredging method, the retreating grouting initial stabilization of silt refers to the initial stabilization of silt within a certain range of the tunnel after drilling to the sudden surge position. The Φ42 small guide pipe with overflow hole is installed after drilling to fill the silt within a certain range of the tunnel to stabilize the sudden surge position and avoid the problem of sudden surge occurring again during the subsequent removal of silt within the tunnel.

[0006] In the aforementioned dredging method, the grouting is a divergent-constrained grouting method, and the grouting sequence is: from the outside to the inside, skip-hole operation, and reinforcement by filling holes.

[0007] In the aforementioned dredging method, the grouting range is: 50m for a single construction length, 10m for grouting reinforcement (referring to the distance from the sudden surge location), and the reinforcement range refers to the area within the excavation outline.

[0008] In the aforementioned dredging method, the grouting pressure is as follows: 2-4 MPa for initial stabilization grouting in the retreating grouting method; and 4-6 MPa for grouting in the front end (10m) with a Φ42 small guide pipe with an overflow hole.

[0009] In the aforementioned dredging method, the slurry mixing ratio is: two-component slurry (volume ratio) C (cement slurry): S (water glass) = 1:1; single-component slurry (weight ratio) W (water): C (cement) = (0.8~1):1.

[0010] Compared with existing technologies, this invention removes silt from the tunnel to a critical state before stopping dredging. The subsequent steps include slope preparation of the silt, pipe installation, mesh installation, shotcreting, backward grouting, grouting with a Φ42 small guide pipe with an overflow hole at the front end (10m), verification, and dredging (including grouting and filling a certain area of ​​silt within the tunnel). This method can effectively seal the silt within a certain range from the point of sudden surge to the tunnel body through grouting, avoiding the risk of further sudden surges during subsequent dredging. It effectively increases the length of each dredging operation, reduces the number of dredging operations, improves work efficiency, and reduces construction costs. Practical application has yielded good results and is worthy of widespread application. Attached Figure Description

[0011] Figure 1 This is a flowchart of the present invention;

[0012] Figure 2 This is a schematic diagram of the longitudinal section of the grouting filling of the present invention (the drainage pipe is omitted);

[0013] Figure 3 This is a grouting and filling hole layout diagram (D1 to D11 are the hole opening sequence);

[0014] Among them, 1 represents a tunnel, 2 represents an adit, 3 represents silt inside the tunnel, 4 represents a steel mesh, 5 represents a drainage pipe, 6 represents shotcrete with mesh, 7 represents a grouting reinforcement area, and 8 represents a silt removal area inside the tunnel. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0016] Example

[0017] This embodiment mainly focuses on the improvement of the method for clearing silt from tunnels filled with horizontal pre-grouting in confined spaces, referring to... Figures 1 to 3This method assumes that the initial support of the formed tunnel section is undamaged or only slightly damaged, except at the location of a sudden surge. First, silt is removed from the branch tunnel and downstream tunnel. Then, silt is removed from the upstream tunnel of the branch tunnel until a critical position and critical state are reached. The critical position and critical state refer to the critical position or state where continuing dredging poses a risk of a sudden surge. Afterwards, the exposed surface of the silt in the tunnel is tidied up, and drainage pipes are installed inside the silt to drain accumulated water or seepage from the sudden surge location. Finally, the exposed surface of the silt in the tunnel is tidied up. The process involves hanging steel mesh on the exposed surface, embedding steel mesh, and spraying C20 concrete (30cm thick). After drilling to the location of the sudden surge, the grout is injected to initially stabilize the silt within a certain range of the tunnel. Then, a hole is drilled in the initially stabilized silt to install a Φ42 small guide pipe with an overflow hole at the front end (10m). Grouting is then performed to fill a certain range of silt within the tunnel to stabilize the sudden surge location and prevent the sudden surge problem from recurring during the subsequent removal of silt within the tunnel. The hole is inspected for verification. Finally, the grout stop wall is removed, and the silt within the tunnel is cleared.

[0018] Grouting principle: divergent-constrained grouting; grouting sequence: from outside to inside, skip-hole operation, and reinforcement by supplementing holes; grouting range: 50m construction length per operation, 10m grouting reinforcement length (distance from the sudden surge location), reinforcement range refers to the area within the excavation outline; grouting method: drill rod retraction type + small guide pipe; grouting pressure: initial stabilization grouting pressure of 2-4Mpa for retraction type grouting; grouting pressure of 4-6Mpa for the front end (10m) with overflow hole Φ42 small guide pipe; grout mix ratio: two-component grout (volume ratio) C (cement grout): S (water glass) = 1:1; single-component grout (weight ratio) W (water): C (cement) = (0.8-1):1.

[0019] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for clearing silt from a confined space by horizontal pre-grouting and filling, characterized in that: The method involves first clearing the silt in the branch tunnel and downstream tunnel, then clearing the silt in the upstream tunnel of the branch tunnel to the critical position and critical state. After that, the exposed surface of the silt in the tunnel is cleaned up, drainage pipes are installed in the silt to drain the water accumulated in the silt or seepage from the sudden gushing points, and then wire mesh is hung and shotcrete is sprayed on the exposed surface of the cleaned silt in the tunnel. The silt is then initially stabilized by grouting, and then a hole is drilled to install a Φ42 small guide pipe with an overflow hole at the front end for grouting to fill the silt in the tunnel. Finally, the grout stop wall is removed, and the silt in the unreinforced section of the tunnel is cleared. Retreating grouting for initial stabilization refers to drilling to the sudden surge location and then retreating to grout and initially stabilize the silt within a certain range of the tunnel. Grouting and filling the silt within the tunnel involves drilling a hole in the initially stabilized silt, installing a Φ42 small guide pipe with an overflow hole at the front end, and grouting and filling the silt within a certain range of the tunnel to stabilize the sudden surge location. Grouting range: 50m for each construction phase, grouting reinforcement length, i.e. 10m from the location of the sudden surge, the reinforcement range is within the excavation outline; The grouting pressure is as follows: 2-4 MPa for initial stabilization grouting in retreating grouting; 4-6 MPa for grouting in Φ42 small guide pipes with overflow holes at the front end.

2. The method for clearing silt from a confined space by horizontal pre-grouting filling, as described in claim 1, is characterized in that: The grouting is a divergent-constrained grouting type, and the grouting sequence is: from the outside to the inside, skip-hole operation, and reinforcement by filling holes.

3. The method for clearing silt from a confined space by horizontal pre-grouting filling, as described in claim 1, is characterized in that... Grout mix ratio: Two-component grout, cement grout: water glass = 1:1, volume ratio; Single-component grout, water: cement = (0.8~1):1, weight ratio.

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