Topology optimization to prevent tunnel heaves under different stress biaxialities

Floor or sidewall heave imposes a severe issue in tunnel construction. We p ropose a two-phase mixture model consisting of the original rock and the fu lly anchored rock mass. The host ground is discretized by finite elements. The relative ratios of two phases in various elements are optimized by opti mality criteria method so that the floor or sidewall heave is minimized. Th e topology of reinforcement is designed to prevent floor heave or sidewall heave of a tunnel surrounded by homogeneous rock. The stress biaxiality k d ictates whether the floor heave or the sidewall heave control the tunnel di stortion. The results indicate the importance to set reinforcement near the tunnel corners to prevent sidewall and floor heaves. Part of the results i s confirmed in the practices. Copyright (C) 2000 John Wiley & Sons, Ltd.