Engineering geological and geotechnical responses of schistose rocks from dam project areas in India

For a rational and safer design of civil and mining engineering structures in or on rocks, a proper understanding of the quality of rock mass is required. To assess the rock mass quality, evaluation of physical and mechanical characteristics of the intact rocks is essential. Especially if the rock is anisotropic in nature, the genetic complexity associated with its petrofabric makes it more difficult to predict its behaviour. In this paper, a comprehensive study of the compositional, physical and geotechnical responses of four varieties of schists, i.e., quartzitic, chlorite, quartz mica and biotite schists obtained from two hydroelectrical project sites in the foot hills of Himalayas, India, has been presented. Anisotropic strength behaviour of the schists has been brought out through the testing of specimens with varying orientation of schistosity with respect to the major principal stress under uniaxial and triaxial conditions. The significance of anisotropic response for consideration in the design is emphasized.