EVALUATION OF FUNCTION OF PASSIVE LOAD FOR TUNNEL LINING

Abstract

A method to analyze the concrete lining of tunnel taking passive loads into consideration is proposed. The basic assumptions used are given as follows : (1) The structural system of the tunnel lining is an arch under the plain strain condition supported elastically at the ends and (2) passive loads acting on the lining are induced in proportion to displacement of the lining toward the surrounding rock over void between the lining and the rock. Using a model, which is almost the same as the tunnel lining of the Shinkansen of Japanese National Railways, many numerical results are obtained for various loading patterns, heights of the rock mass, thickness of the lining and the voids. From the results, characteristics of passive loads associated with magnitude and shape of active loads, the thickness and the void are discussed. Stress reducing effects of the passive loads are significant. But the effects are reduced by the void. Finally, rough standards of the allowable height of the rock mass are presented.