Role of Actual Evaporation on the Stability of Residual Soil Slope

Tropical countries like Singapore are associated with high relative humidity, high temperature, and high amount of rainfall throughout the year. Therefore, flux boundary conditions of slopes are affected by rainwater infiltration and evaporation rate. The research aims to examine the stability of a residual soil slope under arid and damp period conditions. The actual evaporation was utilized in combination with rainfall as flux boundary conditions in the mathematical investigations to study the impact of actual evaporation on the distribution of pore-water pressure and factor of safety variation in residual soil slope. The significance level of actual evaporation in the stability analysis of residual soil slope was tested by performing two instances of seepage analysis on a slope subjected to (1) rainfall only and (2) rainfall and estimated evaporation. The data from the field instrumentation was compared with pore-water pressure variations in residual soil. It was observed that actual evaporation should be incorporated in the numerical analyses as a flux boundary condition in addition to rainfall loading since both actual evaporation and rainfall have a significant effect in generating accurate factor of safety variations and pore-water pressure distribution within soil layers.