A MODEL OF THE TIME-DEPENDENT INTERACTION BETWEEN ROCK AND SHOTCRETE SUPPORT IN A TUNNEL

A viscoelastic model is developed to simulate the tunnel-support inter action of a circular tunnel in a viscoelsatic rock mass. This model ac counts for the time-dependent stiffness and the yielding strain of sho tcrete support. This model is formulated to analyze the effects of the time -dependence of support characteristics on tunnel convergence, su pport pressure, and tunnel-support interaction. Results of a parametri c study reveal that the time-dependence of shotcrete stiffness has a s trong influence on tunnel convergence and support pressure. Ignoring t he yield strain of shotcrete may lead to the underestimation of tunnel convergence and the overestimation of the ultimate capacity of shotcr ete support.