In this study, numerical simulations by elasto-plastic FEM analysis program GeoFem which is developed by Port and Airport Research Institute, were carried out to examine the applicability of GeoFem for the slope stability and the bearing capacity. Through this study, following conclusions are obtained.
1) The bearing capacity factors calculated by GeoFem approximately well agreed to plasticity theory solutions for loose sand with Φ’<30°. However, for dense sand with Φ’=40°, GeoFem calculated the values of Nc and Nq to be smaller than 'plasticity theory.
2) The ultimate bearing capacity of a shallow foundation on the sand layer overlying clay layer was calculated. GeoFem solutions and the bearing capacity equation proposed by Okamura et al. (1998) based on limit equilibrium method, agreed well together regardless of the change of λc and H/B. Yamaguchi's equation was somewhat overestimated compared to GeoFem and Okamura's equation for loose sand. It seems to be because that the assumption of α=30°in Yamaguchi's equation is excessive.
3) The safety factor of gravity type quaywall on the sand ground was calculated. GeoFem solution showed well agreement with the slip circle method (Modified Fellenius' method).
4) The applicability of GeoFem analysis for the stability problem of a ground-sheet pile system was examined in detail. In order to carry out the stability analysis by GeoFem with high accuracy, it seems to be necessary to have finer subdivision of the finite element mesh and to evaluate the friction between the ground and a sheet pile by considering the joint element.
5) The method to calculate the safety factor of a ground-sheet pile system by GeoFem considering the yielding of a sheet pile is proposed. In this method, it seems to be necessary to evaluate approximately the elastic coefficient of ground, Es.
6) From a practical viewpoint, a new slip-circle method is proposed, where the rigidity ofa sheet pile is considered. The applicability of the proposed method for the stability problem of a ground-sheet pile system was examined. Although the safety factors by proposed method and GeoFem do not always coincide with each other, both analyses calculate the similar tendency on the relationship between the safety factor and the rigidity of a sheet pile.