EFFECTS OF MULTIPLE-LAYER SUPPORTING METHOD IN SQUEEZING ARGILLACEOUS ROCKS

Abstract

The multiple-layer supporting method for a tunnel in squeezing argillaceous rocks is defined as the method to control the tunnel displacement within the displacement tolerance. Results of its application to Iiyama Tunnel are described. The respective functions of the first and second layer supports are examined based on the measured tunnel displacement and support stress behaviors. Three-dimensional numerical analysis on this tunneling method is performed to discuss the role of the second layer support applied at different distances from the face. The appropriate execution management conditions are proposed based on the execution experiences. Consequently, it is found to be a very flexible, secure and rational tunneling method.