Travel distance angle for rapid landslides in constructed and natural soil slopes

Rapid landslides in constructed and natural soil slopes have the potential to cause loss of life, destruction of property, and damage to the natural environment because the velocity of the slide mass is such that persons in the travel path do not have time to evacuate and the kinetic energy is such that even small landslides can severely damage buildings and other structures. This paper presents methods for prediction of the post-failure travel distance for rapid landslides from constructed cut and fill slopes and natural soil slopes derived from a database of some 350 rapid landslides in predominantly soil slopes. The characteristics of soils, both dilative and contractive on initial shearing, and the slope conditions for which landslides are susceptible to development into slides of rapid post-failure velocity are discussed. Methods for estimating the travel distance angle of the post-failure travel of the slide mass have been developed and are based on consideration of the failure mechanics of the initial slide (whether contractive or dilative on initial shearing), the type of slope, the slide volume, the geometry of the slope at and below the slide source area, and the degree of confinement of the travel path of the landslide.