The Fully Softened Shear Strength of Lake Agassiz Clays

This paper presents a review of the factors impacting the stability of riverbanks slopes along the Red River of the North which involve Lake Agassiz clays. In particular, the impact of the presence of fissures and micro-fissures and the role of fully softened shear strength in slope stability is discussed. The paper also presents and discusses the results of laboratory testing on disturbed and undisturbed Brenna Formation clay and its relevance to instability. It was found that at the field scale the fully softened shear strength can be a representative lower bound of the strength of the sliding mass not subjected to prior shearing.