Physical and Numerical Investigations on the Stability of Unsupported Vertical Road Cuts in Unsaturated Soils

Publication Title
Physical and Numerical Investigations on the Stability of Unsupported Vertical Road Cuts in Unsaturated Soils

Abstract
Road construction in hilly regions often involves unsupported vertical cuts that appear stable under dry conditions but can fail rapidly during rainfall. This study investigates the rainfall-induced instability of unsupported vertical road cuts, with emphasis on time-dependent failure mechanisms and wetting-front progression under different rainfall intensities. For this purpose, a laboratory-scale 1g physical model of slope was constructed and subjected to drying, controlled cutting and wetting phases with continuous monitoring of matric suction and volumetric water content. The experimental observations were related to the results of finite element numerical analyses performed under varying rainfall intensities. The results highlight that the instability of vertical road cuts is governed by the direction and rate of wetting-front propagation, which is strongly dependent on rainfall intensity. Under light rainfall intensities, wetting-front advancement is predominantly unidirectional leading to delayed, shallow instability. In contrast, moderate to very heavy rainfall intensities induce rapid bidirectional propagation of wetting front resulting in abrupt failure. The study highlights the need to explicitly consider rainfall intensity and duration when assessing the stability and safe excavation depth of unsupported vertical road cuts in landslide-prone regions.
Authors
Eedy Sana; Ashutosh Kumar

Published In

11th International Conference on Physical Modelling in Geotechnics (ICPMG2026)

Theme

Session 3: Resilient geotechnical infrastructure