6. Stability Assessment of Rockfall-Prone Slides in Garhwal Himalayas Using CSMR and Q-Slope Techniques

Rockfall is a natural mass-wasting phenomenon in mountainous regions that involves the detachment of rock fragments by sliding, toppling and falling. The fragments sliding and toppling the hill slopes are often weakened by improper road-cutting, and sometimes are subjected to sliding by rainfall or earthquake occurrences. To minimize the risk, slope stability analysis and its stabilization play a crucial role. In the present study, two rockfall-prone slopes near Shivpuri along NH-58 in the Garhwal Himalayas, India, have been studied. A field study was carried out along this route. The rock mass classification techniques such as Continuous Slope Mass Rating (CSMR) and Q-slope were used for slope stability assessment. The stability grade of these slopes evaluated from CSMR has been validated with Q-slope rock mass classification. The results of Q-slope techniques have been plotted on the Q-slope stability chart and stability condition of both the slopes have been observed. The safe slope angle for both the slopes has been determined using the Q-slope technique. These rock mass classification systems are much more effective for quick assessment of slope stability. Hence, the methodology present in this study will be beneficial for a critical stability assessment of slope vis-a-vis for selection of suitable control measures.