Mesh-free limit analysis of circular tunnel in cohesive soils

ABSTRACT:A novel mesh-free limit analysis approach is presented for stability analysis of a circular tunnel in cohesive soils under plane strain condition. In the presented method the domain is just simulated by nodes and there is no need of elements in the traditional sense. The limit analysis consists of computing lower and upper bounds and, taking the average value as the limit load. In the lower bound analysis the Shepardʹs shape functions are used and, the statically admissible stress field is derived by satisfaction of equilibrium, non-yielding and boundary conditions. The upper bound analysis consists of the establishment of an admissible velocity field which satisfies the compatibility, incompressibility and kinematic boundary conditions. In both approach, the smoothing technique is used to guarantee the rigorousness of bound solutions.