Rock Slope Stability Assessment of Tamhini Ghat and Nearby Areas, Deccan Traps, India, using Rock Mass Characterization and Numerical Modeling Techniques.

Abstract

Landslides and rock falls along the northern part of the western ghats, which is predominantly underlain by the basaltic formations of the Deccan Traps, are very common during the rainy seasons of every year. This region is characterized by steep escarpments, deeply incised valleys, and road cut slopes that are highly susceptible to instability. Developments like road widening, slope cutting with inadequate drainage systems intensify the instability in the province. Removal of earlier slopes without proper strengthening disturbs the natural equilibrium and exposures of new discontinuities, cumulating the possibility of failure. The main focus of the study targets the slope stability analysis of the rock and soil slopes along the Tamhini Ghat of Pune, Maharashtra. This is an attempt to employ a combination of Field mapping, Kinematic analysis, Rock Mass Classification (such as RMR, SMR, Q-slope etc.), and stability analysis techniques to evaluate the slope conditions. The results indicate that the many slopes in the Tamhini Ghat region fall under partially stable to unstable categories. The mechanical properties of these rocks vary depending on the degree of jointing, fracturing, vesicularity, and weathering. The presence of multiple joint sets and flow contacts often creates planes of weakness that act as potential failure surfaces. In addition to this, geomorphological factors such as steep slope angles, differential erosion, and plateau-edge topography enhance the slope failures. Additionally, hydrological conditions play a significant role in stability of slopes in this region. During heavy rainfall, water infiltration leads to increased pore water pressure, reduction in shear strength, and lubrication along discontinuities, thereby triggering landslides and rockfalls. Slope Stability Assessment is done using Finite Element Method (FEM) with help of Phase 2 and Limit Equilibrium Method (LEM) with help of SLIDE 2 softwares. An average factor of safety (FoS) was estimated to be 0.49. Effective mitigation measures such as slope reinforcement, proper drainage management, controlled excavation, and regular monitoring are essential to reduce landslide hazards and ensure safe transportation routes in this geologically sensitive terrain.