An influence line approach to the stabilization of slopes by cuts and fills

Abstract

The effects on stability of concentrated downward and upward influence loads acting at successive positions between the head and toe of a landslide with a fixed failure surface are expressed in terms of influence lines for the resultant changes in the factor of safety. Of particular importance are the positions where no change in factor of safety is produced. On a slope section these are referred to as "neutral points": the traces of these in plan are termed "neutral lines." These concepts provide valuable guidance on the most effective locations and distributions of corrective cuts and fills, particularly for slides on pre-existing slip surfaces.Stabilization of slides by loading the toe is shown to be generally preferable to unloading the head. In complex slides, corrective cuts and fills are best restricted to the extreme head and toe positions, intermediate cuts or fills being avoided.The conditions are defined under which the flattening of slopes by the removal of material reduces stability. In certain cases such a flattening can occur naturally by the local collapse of the steep toe of a landslide. This can lead to an immediate reduction in its factor of safety and a consequent sudden acceleration. Keywords: Slope stabilization, corrective cuts, corrective fills, influence lines, neutral points, neutral lines, slope flattening.