Excavation and support methods for tunnels crossing high-angle thrust water-rich sand-rich faults

Abstract

The invention discloses an excavation and supporting method for a tunnel crossing a high-angle thrust water-rich and sand-rich fault. A circuitous pilot tunnel and a drainage tunnel are arranged on asame side of a tunnel main hole. When excavation and supporting construction is carried out on a construction tunnel, the excavation and supporting method for the tunnel crossing the high-angle thrustwater-rich and sand-rich fault comprises the steps that 1, preliminary excavation and supporting construction is carried out on a rear side tunnel segment; 2, synchronous excavation and supporting construction is carried out on a rear side tunnel segment and a drainage tunnel body of the drainage tunnel; 3, the synchronous excavation and supporting construction is carried out on the rear side tunnel segment, the drainage hole body of the drainage tunnel and a rear side circuitous pilot tunnel segment; 4, the excavation and supporting construction is carried out on a front drainage tunnel body, a front pilot tunnel segment and a middle tunnel segment; and 5, the excavation and supporting construction is carried out on a front side tunnel segment. According to the excavation and supportingmethod for the tunnel crossing the high-angle thrust water-rich and sand-rich fault, the steps are simple, design is reasonable, construction is simple and convenient, the using effect is good, the tunnel hole is excavated by adopting a three-step method, full fracture surface supporting is carried out on the tunnel hole by adopting a double-layer preliminary supporting structure after excavation,and the safety of a later tunnel structure can be ensured.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to an excavation and support method for a tunnel crossing a high-angle thrusting fault rich in water and sand. Background technique [0002] Tunnel support includes advanced support before excavation, initial support and post-support after excavation, and post-support is also called tunnel secondary lining. In order to ensure that the soil body will not collapse or produce quicksand during the excavation process, auxiliary measures such as advance support and grouting reinforcement must be taken for the soil body in front of the excavation. Curtain grouting is to use hydraulic pressure or air pressure to press the solidified grout into the specified rock and soil layer according to the designed concentration through the special grouting hole to fill the cracks or pores in the rock and soil mass, so as to provide a certain range in front of the tunnel. The so...

AI Technical Summary

Problems solved by technology

In water-rich and sand-rich strata, rock mass fragmentation provides more favorable conditions for the occurrence and enrichment of groundwater, and the construction is very difficult. In addition, the stratum contains sand layers, and water and sand gushes are prone to occur during construction. In addition, The dip angle of the fault section is greater than 60°, which is likely to cause catastrophic consequences and seriously affect the safety and efficiency of construction

Therefore, when the tunnel crosses a fault that is rich in groundwater, the rock mass is mostly clastic rock, and is rich in sand and gravel at a high angle and thrusts against a water-rich and sand-rich fault, the construction risks are very high. When the water-rich thrust fault is at an angle, under the action of high water pressure, geological disasters such as water gushing and sand gushing are very likely to occur suddenly on the working face, and the construction risk is high, the construction is difficult and the construction progress is slow

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