ABSTRACT

Sandy ground with a clay layer is frequently encountered in tunnel construction work. However, there are few studies of tunnel face stability for alternate ground. The tunnel face stability is affected strongly by the three-dimensional effect. We evaluated the three-dimensional effect of the tunnel face stability for sandy layers with a clay layer, by applying three-dimensional Rigid Plastic Finite Element Method (3D-RPFEM) and two-dimensional Rigid Plastic Finite Element Method (2D-RPFEM). Special features of the method, which were cleared by results, are shown below. 1) 3D-RPFEM is more sensitive to a clay layer than 2D-RPFEM. 2) 3D-RPFEM expresses remarkably influence in the dilatancy at the upper part of the tunnel.