In major part of the Chamoli, high degree of metamorphic rock are identified. The objective of this research paper is to examine the effect of natural foliation of Chamoli rock on shear characteristics and failure patterns through different anisotropic angles using an automated triaxial system. In present study, seven anisotropic angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) were simulated on a cylindrical specimen of diameter 50mm and length of 100mm based on the natural foliation of rock. From the experimental results and analysis based on Mohr-Coulomb and modified Hoek-Brown criteria, it is observed that the strength of rock decreased from 0° to 30° and the rock strength is continuously increased from 30° to 90°. Simulation of failure patterns in tested specimens are matched to anisotropy planes from 0° to 30°. As per above conclusion the natural foliation (anisotropic) behaviour is catastrophically affected on a strength and failure modes of Chamoli rock.
Himalaya, the juvenile and towering mountain ranges, forming the extra-peninsular and Indo-Gangetic part of the Indian subcontinent, has captivated people since times immemorial and has spiritual significance. The Chamoli, Uttarakhand area under scrutiny is one such part of the Lesser Himalaya which still confirms a number of natural landslide/rockslide records and had come in for many unsolved problems. Then some researchers worked on, (Oldham 1883, 1888; Middlemiss 1885, 1887) mapping of the Kumaun-Garhwal Lesser Himalaya and represent its geology. The rocks of the Kumaun and Garhwal Lesser Himalaya have been subjected to recapitulated stages of crustal movements (Auden 1937; Gairola 1975; Kumar and Agarwal 1975; Gairola and Srivastava 1982) which has derived in very complicated geology. The rocks type (D. H. Shugar et al. 2021) of the Chamoli region which is high to medium metamorphic rock (gneiss & schist) contains abundant of soft, platy, oriented minerals, and weathering will further weaken these rocks. In spite of many attempts made in the past to describe the engineering performance of transversely anisotropic rocks still their nature is not adequately understood. The oriented structures within the rock matrix such as schistosity, foliation, lamination and/or cleavage are responsible for anisotropic behaviour of rocks (Goodman 1989; Singh et al. 1989; Ramamurthy 1993; Nasseri et al. 2003; Esamaldeen et al. 2014).
