抄録
Since the engineering design codes are updated with the new knowledge and experience, there is a need to reprove the stability of engineering structures. In many cases only a limited field investigations and data on soil properties are available. Therefore, in many cases the strength characteristics are obtained based on SPT N values. Mainly the stability of the slopes is expressed trough the factor of safety, but in the case of earthquake action more important are residual deformations. A relatively simple method for calculation of residual displacement is the Newmark′s sliding block method for slope stability. Stability analysis was made on dam ″A″ and a damaged embankment during the Kobe earthquake. In both cases only a standard penetration testing was performed. Since no testing on strength properties of the soil was made, strength properties of the soil are estimated based on SPT-N values trough empirical relationship between SPT N values and the angle of internal friction at peak strength. Since during the strong earthquakes the soil exhibits plastic behavior, the values of the residual friction angle is lower than the friction angle at peak especially in the case of medium dense and dense conditions, together with dilatancy and the effective pressure at failure. Moreover, the difference between peak and residual angle of internal friction is significantly influenced by the relative density which was obtained from the empirical relationship with the SPT-N values. In the case of dam ″A″ the residual deformation are compared with the one from the FEM analysis, while in the case of the embankment the computed residual deformation are compared with the observed after the Kobe earthquake. Good estimation of the residual displacement is obtained when using the residual angle of internal friction in the analysis.
