Geosynthetic-Reinforced Slopes in Cohesive Soils Subject to Seismic Action

Abstract

Currently, geosynthetic reinforcements are calculated assuming the backfill to be purely frictional. However, accounting for the presence of even a modest amount of cohesion may allow using locally available cohesive backfills to a greater extent and less overall reinforcement. Unlike purely frictional backfills, cohesive soils present are subject to the formation of cracks that tend to reduce slope stability which therefore need to be properly accounted for in any slope stability assessment.Utili & Abd [1] derived a semi-analytical method for uniform c-ϕ slopes accounting for the presence of cracks that provides the amount of reinforcement needed as a function of soil cohesion, tensile strength, angle of shearing resistance and slope inclination employing the limit analysis upper bound method.In this paper the formulation is extended to the seismic case, accounting for earthquake action by employing the pseudo-static approach. Ready to use design charts providing the value of the required reinforcement are plotted for both uniform and linearly increasing reinforcement distributions. From the results it emerges that accounting for the presence of cohesion allows significant savings to be made, but the presence of seismic action may require considerable additional reinforcement.