Method for constructing water-rich weak surrounding rock tunnel crossing fault broken belt

Abstract

The invention discloses a method for constructing a water-rich weak surrounding rock tunnel crossing a fault broken belt. The method comprises the following steps that firstly, construction is carriedout on a plurality of tunnel sections in a construction tunnel from front to rear, and when any tunnel section is constructed, the construction method comprises the following steps that 1, advanced support is carried out on a pipe shed; 2, tunnel excavation and initial support are carried out, wherein upper peripheral side hole excavation and initial support are carried out, reserved core soil area hole excavation and initial support are carried out, first hole excavation and initial support are carried out firstly and thereafter second hole excavation and initial support is carried out; and3, tunnel secondary lining construction is carried out. The method has the beneficial effects that the design is reasonable, construction is easy and convenient, and the use effect is good; the self-drilling pipe shed is adopted to carry out advanced support on the upper hole body before excavation, and two-step method excavation is adopted, so that the construction efficiency can be effectively improved; meanwhile, the whole reinforcing structure of the hole peripheral rock, the tunnel primary support structure in holes and the tunnel secondary lining are connected to form an integral supportsystem with a stable structure, the stability of the tunnel structure can be effectively improved, and the safety of the later tunnel structure is ensured.

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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