Energy approach to seismically induced slope failure and its application to case histories

An energy approach is proposed here to make a simple evaluation of travel distance of debris during seismically induced slope failures. In the evaluation, earthquake energy and gravitational potential energy are dissipated in large flow deformations. Shake table tests on dry sand slopes together with theoretical consideration on a rigid block model are revisited to show that measured slope displacements can be evaluated by the proposed energy approach if an appropriate friction coefficient of the slope is specified. Then, slope failures during recent earthquakes are investigated, and the energy approach is applied to them. Mobilized friction coefficients during failures are back-calculated, revealing their strong dependency on initial slope inclinations. The friction coefficients are found to be smaller than the initial slope inclinations for gentler slopes, indicating that the failed debris tends to accelerate. The friction coefficients tend to decrease with increasing volume of failed slopes, which is consistent with previous case studies on huge landslides.