Construction method of water-rich and weak surrounding rock tunnel crossing fault fracture zone

Abstract

The invention discloses a construction method for a water-rich and weak surrounding rock tunnel crossing a fault fracture zone, in which a plurality of tunnel segments in the constructed tunnel are respectively constructed from back to front, and when any tunnel segment is constructed, the following steps are included: The following steps: 1. Advance support of the pipe shed; 2. Tunnel excavation and initial support: excavation and initial support of the upper surrounding side cave body, excavation of the cave body and initial support in the reserved core soil area, and first excavation Tunnel excavation and initial support and post-excavation Tunnel excavation and initial support; 3. Tunnel secondary lining construction. The invention is reasonable in design, simple in construction and good in use effect. Before excavation, the self-drilling pipe shed is used to carry out advanced support on the upper cave body, and the two-step method is adopted for excavation, which can effectively improve the construction efficiency; at the same time, the surrounding rock The overall reinforcement structure is connected with the primary support structure of the tunnel in the tunnel and the secondary lining of the tunnel to form a structurally stable integral support system, which can effectively improve the stability of the tunnel structure and ensure the safety of the later tunnel structure.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a construction method for a water-rich and weak surrounding rock tunnel passing through a fault fracture zone. Background technique [0002] In recent years, among underground projects such as railway tunnels, highway tunnels, and urban subways that are being built and planned, soft rock tunnels (also known as soft surrounding rock tunnels) account for a high proportion, and the length and span of the tunnels are also increasing. A large number of tunnels are still in special geology, such as loess with large pore structure, water-rich fully weathered granite, water-rich fault fracture zone, debris flow stratum, sandy pebble stratum and loose accumulation bodies, etc. It is extremely difficult to build large-section and long-span tunnels in these strata, and landslides often occur during construction. Among them, the fault fracture zone refers to the rela...

AI Technical Summary

Problems solved by technology

When adopting the step method to excavate the water-rich and weak surrounding rock tunnel passing through the fracture zone of the stratum, due to the large number of excavation sections, the construction is difficult and the construction risk is high, especially when the tunnel excavation section is large. It is very difficult, and it is easy to cause large-scale subsidence of the vault during the excavation process. After excavation, the deformation rate of the vault is fast, the subsidence is too large in a short period of time, and the side walls and arches are twisted and deformed. Serious In this case, if the conventional support system is adopted, the deformation is very controlled, and the construction time is long, and the surrounding rock is exposed for a long time, which may easily cause large-scale encroachment of the surrounding rock, spalling of shotcrete, and The distortion and deformation of the steel frame will further increase the risk of collapse, and the safety and quality cannot be guaranteed. At the same time, it also seriously restricts the construction period

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