Evaluation of soil-nail pullout resistance using mesh-free method

Soil nailing has been widely used in the world during the last two decades; because of its technical and economical advantages. The shear strength versus displacement behavior of soil-nail interface has significant effects on economic and safety design of a soil-nail system. In this paper, by application of mesh-free method, MFM, a new approach is presented to investigate the behavior of interface in soil-nail pullout process and also the interaction between nail and surrounding soil. Simulation of soil-nail interface in mesh dependent methods such as finite element method, FEM, has been associated with problems of heterogeneous deformations. In the presented method, the problem domain and its boundary are represented by using sets of nodes scattered in the problem domain and on its boundary. Interaction between nail and surrounding soil is simulated using interface layers with small thickness which is able to model slippage between nail and surrounding soil. The model is based on a Mohr-Coulomb failure criterion, including deviatoric hardening/softening during pre and post peak pullout point and ultimate state. A computer code has been developed to simulate elasto-plastic soil-nail pullout behavior. Simulation results show good performance of MFM in numerical simulation of soil-nail interaction and also soil-nail pullout resistance.