A study of soil-nailed wall behaviour at limit states

A detailed study of soil-nailed wall behaviour is investigated under limit states by the three-dimensional finite-difference method. To simulate failure conditions and to investigate the failure surface, two kinds of limit states are modelled: (a) by applying a uniform pressure on top of the wall (called load collapse) and (b) by reducing the shear strength of the soil (called the strength reduction method). For cohesion soils where the soil friction angle is low, the slip surface is in good agreement with circular shapes. However, tension cracking is caused and the factor of safety obtained is smaller than those found by the limit equilibrium method. For granular soils, the shape of the slip surface is trilinear and bilinear under the associated and non-associated flow rule, respectively. Moreover, some results support and improve the current method of design in using the assumptions of interaction between the nail and soil at the limit state which is discussed in this paper.