THE STUDY ON WATER-RESISTING AND MUD-RESISTING ROCK-SOIL PLATE AND ITS FAILURE PATTERNS

In tunnel excavation, there exist the water inrush and mud burst disaster-causing structures which are closed to the excavated surface or are outside of the contour lines. Due to the thickness of water-resisting and mud-resisting rock-soil plate, located in the water inrush and mud burst disaster-causing structures between the excavated surface and the front of the excavated surface or between the excavated contour line and outside of the excavated contour line, is less than the minimum safety thickness of the rock-soil plate, and under the stress of the underground water of the water inrush disaster-causing structure or the stress of the clay of mud burst disaster-causing structure, water-resisting and mud-resisting rock-soil plate is instable, water inrush or mud burst disasters are triggered in tunnel excavation. Based on the cases of water inrush and mud burst disasters in decade, this paper summarizes and proposes the structure types and the patterns of the water-resisting and mud-resisting rock-soil plate causing water inrush and mud burst disasters. It also analyses five types of the water-resisting and mud-resisting rock-soil plates:the various sizes of broken rock blocks with or without clay(rock particles and sand-cobbles),the fractured rocks filled with or without fractured clay, the clay or fault gouge, the complete rock, and the water-resisting and mud-resisting rock-soil initial support plate. Meanwhile, on the fundament of those five types of the water-resisting and mud-resisting rock-soil plates, this paper presents five failure patterns:seepage(collapsibility) failure, shear failure, softening and burst failure, cracking and burst failure, and bending failure. It also analyses the interrelations between the structure types and the patterns of the water-resisting and mud-resisting rock-soil plate.