Mechanism of water inrush from the tunnel face induced by fault and its application

Abstract

The limit equilibrium method, slice method and elastic mechanics method are adopted to investigate the mechanism of water inrush from the tunnel face induced by fault. Semi-analytical expressions of the minimum safety thickness of the rock resisting water inrush are derived. The safety thickness calculation method is applied to the actual tunnel engineering, and the accuracy of the proposed method is verified by comparing with the actual excavation results. On this basis, the minimum safety thickness affected by karst water pressure, fault dip, vertical force, width and shear strength indexes of the fault fracture zone are further analyzed and discussed. The results show that: 1) The minimum safety thickness increases with karst water pressure; 2) As the fault dip increases, the minimum safety thickness first increases and then decreases, and water inrush from the tunnel face is prone to occurring when the fault dip is between 45° and 60°; 3) The minimum safety thickness linearly increases with the width of fault fracture zone; 4) The minimum safety thickness linearly decreases with the increase of shear strength of the fault fracture zone; 5) The minimum safety thickness increases with vertical force on the fault fracture zone. The research results provide a new idea for calculation methods and theoretical research of water inrush in karst tunnel, which has certain reference significance and application value for similar projects.

Keywords

limit equilibrium method / slice method / elastic mechanics method / water inrush mechanism / fault

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