SHALLOW SLIPS IN HIGHWAY EMBANKMENTS CONSTRUCTED OF OVERCONSOLIDATED CLAY

Highway embankments constructed of overconsolidated clay at conventional side slopes have been prone to shallow slope failure a few years after construction. The extent of the problem and areas currently at risk are identified. Factors likely to increase the risk of a slip and probable mechanisms of failure are described. Effective stress parameters are suggested for use in analysis and problems in determining these parameters are discussed. Back analysis and parametric sensitivity studies are described. The investigation of a slipped area and field trials of various repair techniques are briefly reported. The techniques, some including the use of geogrids, are considered as alternatives to the conventional "excavation and granular replacement" repair method. Comment is made on the future design of embankments in overconsolidated clay. For the covering abstract of the symposium see IRRD 286603. (Author/TRRL)