Stability control construction method of water-enriched soft rock tunnel passing through fault crushed zone

Abstract

The invention discloses a stability control construction method of a water-enriched soft rock tunnel passing through a fault crushed zone. A plurality of tunnel segments in a construction tunnel are constructed respectively from back to front. During construction of any one of the tunnel segments, the method comprises the following steps: 1, performing pipe shed forepoling; 2, performing tunnel excavation and preliminary bracing: performing upper peripheral side cavity excavation and preliminary bracing, performing a reserved core soil area cavity excavation and preliminary bracing, excavatingthe cavity which is excavated firstly and performing preliminary bracing as well as excavating the cavity which is excavated secondly and performing preliminary bracing; and 3, performing tunnel secondary lining construction. The method is reasonable in design, simple and convenient in construction and good in use effect; before excavation, the upper cavity is subjected to forepoling by a self-drilling pipe shed and is excavated by a two-step method, so that the excavation efficiency is effectively improved; and meanwhile, an integral supporting system with a stable structure, which is formedby connecting a surrounding rock integral reinforced structure outside the cavity and a tunnel preliminary bracing structure and tunnel secondary lining, can effectively improve the stability of thetunnel structure and guarantee the later safety of the 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 stability control of water-rich soft rock tunnels passing through fault fracture zones. 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 r...

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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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