Analysis of Tunnel Support Structure with Consideration of Support/Rock Interaction

Procedures are given for calculating stresses in underground tunnel supports which accounts both for the structural behavior of the support and that of the adjacent rock mass. Stresses in the support are caused by service loads and rock reactions. Service loads are due to rock pressures, hydrostatic and hydraulic pressures, selfweight of the support, or other utilitarian-type loads. Rock reactions, equal and opposite those in the support, are due to the deformational interaction that results as service loads deform the tunnel support against the adjacent rock mass. The procedures developed for solving this problem are an application of matrix structural analysis. The principles involved in this method allow for the consideration of the deformable characteristics of most tunnel support systems and an iterative solution procedure is applied to determine the areas of support-rock interaction. Numerical results of example problems are given.