Engineering With Cut Rock Slopes on Highways:Geotechnical Perspective

Abstract

Infrastructure development in the Himalayan region frequently requires steep rock cutting, particularly during highway widening and road construction. Although rocks are generally considered strong and capable of supporting heavy loads, Himalayan rock masses are often highly fractured and intersected by numerous joints, making them weak and anisotropic. The stability of these rock slopes largely depends on the orientation, dip, dip direction, and other geological characteristics of the joints. Therefore, proper assessment of rock mass stability is essential before carrying out excavation activities. This lecture highlights the key properties of rock joints that must be identified and mapped during field investigations to evaluate potential slope failures. It also emphasizes the additional instability caused by foundations constructed on slopes. While detailed geotechnical analysis and design are important for ensuring safe excavation, the complex geological conditions, limited time, and financial constraints often make such investigations impractical for every road section. To address these challenges, a simplified rock mass classification approach is proposed to estimate safe cutting heights using basic field observations. Furthermore, practical design charts are developed to assist field engineers in making quick and reliable assessments of slope stability, ultimately supporting safer and more efficient infrastructure development in the Himalayan region.