DEFORMABILITY OF COMPACTED TECTONISED CLAY IN CONTROLLED-SUCTION OEDOMETER TESTS

摘要

Due to their structural features and natural water content, scaly clays may be placed and compacted as excavated to obtain a material with adequate engineering properties, suitable as core material in earth dams and in waste isolation fills. A reliable prediction of the field performance of these constructions during different stages of their design life requires the characterisation of the material under partially saturated conditions, and its response during cyclic suction variations. In order to investigate these processes and to identify the relevant features of soil behaviour, an experimental programme was performed on compacted scaly clay using controlled-suction oedometer cells. Applied stress paths included loading and unloading cycles at constant matric suction and controlled-suction wetting-drying cycles at constant vertical net stress. Selected results pointed out that during wetting and drying cycles, samples experienced progressive shrinkage as the suction cycles accumulated, which was larger at higher stresses. However, a quasi-reversible response was approached as the number of cycles increased. Test results have been interpreted within the framework of a suction-dependent elastoplastic constitutive model.