Effects of flux boundary conditions on pore-water pressure distribution in slope

Abstract

Many geotechnical analyses commonly ignore the flux boundary conditions at the ground surface to avoid the complexity in determining the actual flux values at the soil-atmosphere interface. However, actual flux boundary conditions can be an important input to many geotechnical analyses, especially those related to unsaturated soils. Therefore, the effects of flux boundary conditions on pore-water pressure distribution in a residual slope are investigated in this paper. The study focuses on infiltration and evaporation processes. The characterization of climatic data in Singapore is presented in this paper to illustrate the quantification of flux boundary conditions. Evaporation rate for the seepage analyses is calculated using Penman's method. The classification of Singapore climate is carried out using Thornthwaite index.The typical differences between air and soil temperatures in Singapore are presented in this paper using case study from a residual soil slope at Yishun, Singapore. Finite element seepage analyses were conducted to investigate the effect of rainwater infiltration and evaporation on pore-water pressure distribution of a residual soil slope at Jalan Kukoh, Singapore. The numerical analysis results show good agreement with those obtained from field measurements if the evaporation is applied in the analyses during the drying process. This indicates that rainfall and evaporation play important roles in pore-water pressure changes within soil slope.