Strength of Weathered Melbourne Mudstone

Abstract

The mudstone underlying the Melbourne area forms the principal bearing stratum of the region. Because of its wide range of weathering characteristics, the mudstone is transitional between soils and more competent hard rocks. Little quantitative engineering data is available for these weak rocks and therefore a comprehensive series of laboratory tests including uniaxial compression tests, Brazilian tests, direct shear tests and triaxial compression tests, on several hundred individual intact specimens of the mudstone were performed. The variation of strength across a wide range of weathering characteristics is investigated. The suitability of several failure criteria is examined. A new nonlinear criterion is proposed and is shown to adequately predict the strength of the mudstone for the range of testing conditions considered.