ABSTRACT
This paper describes findings of a series of experiments carried out to characterize physical and mechanical behaviour of Katra sandstone—a Middle Siwalik sedimentary rock of the Himalayas. Being sandwiched between two active tectonic thrusts—Main Boundary Thrust and Main Frontal Thrust towards north and south respectively and also being a young sedimentary sequence, the rock mass of Siwalik Himalayas have been subjected to stress induced deformations.
The experimental results reveal following characteristics of Katra sandstone (i)Microstructural analysis shows coarse grained matrix comprising of fractured quartz grains alongwith more than 25% of feldspar and mica (ii)Uniaxial compressive strength of dry and saturated Katra sandstone varies from 8–25 MPa and 2–8 MPa respectively (iii)Post failure behaviour of the rock depicts increase in strength and failure strain with increase in strain rate from 10–3/s to 10–1/s. (iv)Under uniaxial compression in strain controlled mode, Katra sandstone mostly shows axial splitting failure which changes to single and conjugate shear failures under triaxial compression (v)Triaxial stress-strain curves of Katra sandstone demonstrate an increase in strength with confining pressure (vi)Volumetric strain was characterized by initial phase of compaction dominated behaviour followed by dilatancy
