Excavation method of tunnel crossing high-angle thrust water-rich sand-rich fault

Abstract

The invention discloses an excavation method for a tunnel passing through a high-angle thrust water-rich and sand-rich fault. A construction tunnel hole is divided from the top to the bottom into an upper hole body, a central hole body, and a lower hole body, wherein the upper hole body is divided into a left guide hole and a right guide hole. A primary support structure of the tunnel hole is a double-layer primary support structure. During the excavation of the construction tunnel, the construction tunnel is divided into a plurality of tunnel segments from the back to the front for excavation. During the excavation of any one tunnel segment, the method comprises the steps: 1, performing the excavation of the upper hole body and the primary supporting; 2, performing the excavation of the central hole body and the primary supporting of an outer layer; 3, performing the excavation of the lower hole body and the primary supporting of the outer layer; 4, performing the primary supporting of an inner layer; 5, repeatedly performing the steps 1-4 for many times, and completing the excavation of the tunnel. The method is simple in step, is reasonable in design, is convenient for construction, is good in use effect, employs a three-step method for the excavation of the tunnel hole, employs double primary support structure for the full-section support of the tunnel hole after excavation, and can guarantee the safety of the tunnel structure later.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to an excavation method for a tunnel crossing a high-angle thrusting water-rich and sand-rich fault. Background technique [0002] The fault fracture zone refers to the relative movement of the two disks of the fault and the mutual extrusion, which breaks the nearby rocks and forms a fracture zone roughly parallel to the fault plane, referred to as the fault zone. In China, high-angle thrust faults with a cross-sectional dip greater than 45° or 30° are called thrust faults. It is very difficult to construct tunnels that cross high-angle thrust faults. The above-mentioned high-angle thrust faults refer to thrusts with a cross-sectional dip greater than 60° Fault. Especially when the formation is rich in water and sand, the construction is more difficult. Water-rich and sand-rich formations are also called water-rich sand formations, which refer to formations...

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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