Groundwater and earthquakes: Screening analysis for slope stability

Groundwater is a factor behind the occurrence of landslides, and so is the action of seismic shaking in sloping terrain. This paper presents closed-form expressions for the factor of safety and yield coefficient of slopes subjected simultaneously to seismic forces and variable groundwater conditions. Two failure modes of natural slopes are considered in this work, namely, long slope with phreatic surface parallel to the ground surface and slope with emerging phreatic surface. For these failure modes, the factor of safety and yield coefficient are determined for various conditions of drainage using effective-stress analysis and total-stress analysis. The effect of soil strength reduction by seismic loading is accounted for in the derived factors of safety and yield coefficients. The specification of the lateral seismic coefficient for equivalent seismic loading relies on recent advances in geotechnical earthquake engineering and seismic engineering geology. The role of liquefaction and clay softening is introduced in the analysis of seismic slope stability and slope deformation considering variable groundwater conditions. Several examples illustrate the application of the methods herein presented. (C) 2015 Elsevier B.V. All rights reserved.