Use of residual strength for stability analyses of embankment foundations containing preexisting failure surfaces

Abstract

Three case histories are described which involve the construction of major bridge approach fills on heavily overconsolidated clay or clay shale foundations, in which the residual strength of the foundation materials governed the design. The case histories are well documented by both field and laboratory observations.The difficulties of detecting thin preexisting failure planes in overconsolidated foundation materials are described. The case histories demonstrate that for such foundation conditions, and where major structures are involved, unusually thorough sampling, field instrumentation and laboratory testing programs are justified, and can provide the required data to permit a reliable stability analysis.