Abstract
A method for predicting slope failure that is based on seepage analysis and the stability analysis of a slope is presented. Lateral unsaturated seepage flow is discussed as well as vertical one, and the seepage flow in a saturated zone is calculated in one or two dimensions taking into account the influence of the coefficient of permeability of saturated soil and the lateral unsaturated seepage flow. The threshold condition of slope failure is evaluated by making a stability analysis of a slope of infinite length. The method was used in an experiment and in the field. When the lateral unsaturated flow was taken into account, the theoretical data for the water level in the slope was in good agreement with the experimental data. In the simulation of slope failure in the field, a coefficient of permeability for saturated soil was taken to be 10 times that obtained by the standard permeability test as the representative coefficient of permeability for saturated soil with large pores may be about 10 times that found by the standard permeability test, in which the sample core was too small to include a large size pore. Use of such a larger coefficient improved the accuracy of prediction for the places and times of slope failure.

【Key words】: slope failure, hazard prediction, seepage analysis, surface landslide, unsaturated seepage