Shear strength of soft fissured clays

Case histories of failure of water-retaining structures on highly plastic clay indicate that the intact strength of the clay does not reliably predict the stability condition. A study of the foundation conditions revealed the presence of structural discontinuities such as nugget and blocky structure, joints, fissures, and slickensides. A re-analysis of the failures, using the normally consolidated strength of the soft highly plastic clay, as suggested by Skempton and Hutchinson for stiff fissured clays, gives a more reliable prediction of the in situ stability condition.