Techniques for Determining the Geofiltration Properties of Clayey Soils Related to the Design of Seismically Stable Suffosion Earthen-Rock Dams

Abstract

The seismic stability of earth dams for the most part is evaluated based on mechanical stability characteristics of the retaining prisms; these are analyzed by numerical methods with allowance for the additional loading generated by a seismic wave of specified magnitude on its passage through the dam location. One may quote a whole range of instructive examples [1, 2] of seriously damaged earth dams (including cases with catastrophic consequences) associated with fractures of the earth dam’s body that were caused by earthquakes and then aggravated by the scour (suffosion) of the fractures by infiltrated water. Obviously, a major threat is posed by transverse through-the-body fractures at the waterresistant wall where tensile stresses to which the material is subjected are close to critical. Consequently, neglect of a detailed analysis of the conditions that lead to the emergence of stress-strain and seepage (filtration) states in the water-resistance structure of a dam to be erected in a seismically active region will not allow reliable evaluation of the dam’s resistance to filtration — even in the provision of piezometric slopes (hydraulic gradients) of the filtration flow in conformance with standard design requirements [3].