Control of structural damage on the rock mass characteristics and its influence on the rock slope stability along National Highway-07, Garhwal Himalaya, India: an ensemble of discrete fracture network (DFN) and distinct element method (DEM)

The existing structural discontinuities such as faults, joints and cleavages in rock slopes control the rock mass properties. The presence of structural discontinuities is strongly influenced by the regional tectonic structures. The concept of damage as applied to intact rock and rock mass relates to the degradation of their strength properties. The high variability in fracture intensity and trace length has been found as one move away from the hinge zone due to damage caused by regional syncline in Garhwal Himalaya. The high in situ stresses in fold hinge zone during folding propagated the fractures utmost and result in a high frequency of mean-sized fractures. The high fracture intensity and nearly equal joint traces intersected comparatively smaller-sized blocks. Whereas the rock mass away from the damage zone (fold core) at sites 2 and 3 comprises low fracture intensity and intersects relatively larger-sized blocks. Deterministic and stochastic DFN approaches were implemented in 3DEC to model the rock mass conditions within and away from damage zone. The study provided a comprehensive insight into rock mass behavior using structural investigation and numerical modeling. The work concluded that the high fracture intensity in fold hinge zone reduced the rock mass strength, providing the kinematic freedom to blocks resulting in slope failure.