Abstract:Stability analysis of inhomogeneous soil slope is one of classical problems for soil mechanics. The authors establish a rotational failure mechanism with combination of different logarithmic spiral arcs based on the theory of limit analysis method. When slip mass is looked upon as rigid-body,the layered soil slope can be discretized and meshed by triangle elements which are the pre-processor of the ANSYS software. According to upper bound theory of limit analysis method,not only every triangle element¢s external work-rate done by self-weight and seismic force but also the internal energy dissipation produced in different logarithmic spiral arcs can be totally calculated. By means of strength reduction method and virtual work-rate equation for upper bound theorem,the calculation formula of upper bound solution with rigid elements for inhomogeneous soil slope stability analysis can be deduced. As an example of two layered soil slope,the factor of safety is computed by different methods such as Sweden slice method,Bishop method,Janbu method and upper bound approach of rigid elements. The results show that the new method can obtain the upper-bound solution for layered soil slope,but the value of factor of safety calculated by the method of Bishop is close to the lower-bound solution. It is very important to choose proper solution of factor of safety when the upper limit and lower limits are certainly made. At last,the new method has good applicability for layered soil slope stability analysis.