Abstract
Strength parameters which should be used for the calculation of slope stability analysis of landslide are discussed and a new method of determining the parameters for design use is proposed. The authors assume that the strength decrease due to the increase of pore water pressure along the potential slip surfase can be represented by a function of overconsolidation ratio (OCR) defined by the ratio of effective stresses before and after the increase of pore water pressure. It is also assumed that the strength decrease due to the state change of the material around the potential slip surface from soft rock to overconsolidated clay due to weathering etc. can qualitatively be represented, by the change of OCR.
Based on the assumption, the authors derive an equation representing the change of effective strength parameters cd, φd, which varies in between peak and residual state, as a continuous function of OCR. In addition, a practical method of determining strength parameters for stability calculation is proposed, in which the parameters are given by combining the conventional reverse calcuation method with the laboratory shear test results.
