Crossing high-angle thrust water-rich sand-rich fault tunnel excavation and drainage construction method

Abstract

The invention discloses a crossing high-angle thrust water-rich sand-rich fault tunnel excavation and drainage construction method. A tortuous pilot tunnel and a water release hole are formed in the same side of a front hole of a construction tunnel. The construction process includes the steps: first, preliminarily excavating and constructing a rear tunnel section; second, synchronously excavatingand constructing the rear tunnel section and a drainage hole body of the water release hole; third, synchronously excavating and constructing the rear tunnel section, the drainage hole body of the water release hole and a rear tortuous pilot tunnel section; fourth, constructing a front water release hole body, a front pilot tunnel section and a middle tunnel section; fifth, constructing a front tunnel section. The method is reasonable in design, simple and convenient in construction and good in use effect, water on an upper wall of a fault is drained by the high-level water release hole between the front hole of the tunnel and the tortuous pilot tunnel, drainage is assisted by the tortuous pilot tunnel excavated before the front hole of the tunnel, the front fault condition of a tunnel face of the front hole is verified in advance, the water in the fault can be maximally drained, water pressure in the front fault of the tunnel face is reduced, construction safety of each tunnel face can be ensured, and construction period is shortened.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to an excavation and drainage construction method for a tunnel crossing a high-angle thrusting fault rich in water and sand. 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, w...

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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