Static analysis of tunnels in blocky rock masses by using a Cosserat equivalent continuum

The Cosserat continuum theory has several advantages over the classical theory when the behavior of a discontinuous rock mass is to be studied by means of the equivalent continuum approach, especially if the bending stiffness of the rock layers and relative rotation of the blocks play an important role in the problem to be solved. In this paper an equivalent Cosserat continuum is used to study the elasto-plastic behavior of a shallow tunnel in a blocky rock mass. Several FEM analyses were carried out to investigate the influence of the block size - tunnel radius ratio on static behavior.