RMR and RHRS of Ngaizel Road cutting section, Aizawl, Mizoram

Abstract

Due to unfavourable topographical features roads in hilly areas are usually small as compared to plain areas, therefore several problems may arise whenever rockfall occurs. One of the busiest domestic road in Aizawl i.e. Ngaizel road often encountered rockfall along its cutting slope. This road act as an important gateway which connects the southern parts of Mizoram. This road is packed with human activities which adds on the hazard level to rise high. The main factors that contribute to rockfalls include slope degree, geomechanical properties of rock mass and anthropogenic activities. Taking into consideration of all the adverse effect of rockfalls, RMR (Rock Mass Rating) become indispensable to identify the actual condition of rock mass on the slope of the study area. RMR classification is carried out to determine the geomechanical condition of slope rock mass and Rockfall Hazard Rating System (RHRS) is applied for identifying the hazard-prone area of rockfall along the cut slope of Ngaizel road. RHRS depends on various parameter which include slope height, annual precipitation, block size, block volume, decision sight distance, average vehicle risk, road width and rockfall history which mainly concern about the safety of pedestrians along the road. The RMR and RHRS study along Ngaizel cut slope provides a detailed and useful information about the geological condition and delineating the hazard level. The study also gave awareness and alertness about the actual condition of the area.