Abstract
In the last two decades, there has been a significant increase in infrastructure development on slopes of hilly regions of the world, due to population growth. There are many infrastructures on unsaturated expansive slopes, especially in semi-arid and arid regions. Rainfall infiltration is one of the major factors that contributes to the slope and infrastructure foundations failures on hilly slopes with unsaturated expansive soils. In the current study, a rational approach is proposed considering the combined influence of the foundation-slope behavior based on the principles of unsaturated soil mechanics. This is achieved by a novel numerical modelling approach using the commercial software Geo-studio to investigate the performance of strip foundation located on the top of the unsaturated expansive soil slope subjected to various rainfall infiltration conditions. Hydro-mechanical coupling analysis is conducted to evaluate the rainfall water infiltration influence combined with slope stability analysis using limit equilibrium method. Comparisons are made between both the foundation bearing capacity, slope stability before and after rainfall water infiltration. Different failure mechanisms of the foundation and slope system are presented with and without foundation loading for various rainfall scenarios. Results summarized in this paper are helpful for the geotechnical engineers for understanding the performance of shallow foundations on unsaturated expansive soil slopes considering the influence of rainfall infiltration conditions.
Highlights
The growth of population in various regions of world during the last five decades has promoted significant increases in human settlements on hilly regions
These studies highlight how matric suction decreases in unsaturated soils due to rainfall infiltration which in turn contributes to a reduction of soil shear strength and slope factor of safety (FS)
These locations are at the slope top, beneath the foundation, mid slope and slope toe shown in Figure 1 as section 1-1, 2-2, 3-3 and 4-4 respectively
Summary
The growth of population in various regions of world during the last five decades has promoted significant increases in human settlements on hilly regions. The slope stability of unsaturated soils have been widely investigated considering the influence of rainfall conditions (Qi & Vanapalli [2], Ng et al [17], Khan et al [18]) These studies highlight how matric suction decreases in unsaturated soils due to rainfall infiltration which in turn contributes to a reduction of soil shear strength and slope factor of safety (FS). Some of these studies provide rational interpretation of the slope stability by taking account of the hydro-mechanical behavior of expansive soils (Qi & Vanapalli [2]) The results of these studies suggest that shallow surface failure is a common failure mechanism and may be associated to the cracks and fissures that form due to the evaporation in drying period and the water infiltration in rainy seasons (Qi & Vanapalli [2], Khan et al.[18]). The relationships between the soil properties; namely, the variation of shear strength and modulus of elasticity with respect to the matric suction have been considered in the model
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