A protective measure for expansive soil slopes based on moisture content control

Abstract

For expansive soil slopes, the primary failure mode is surface- or shallow-layer slide, which can occur easily under repeated rainfalls. In this investigation, a field testing program is implemented on five expansive soil slopes with different inclination subjected to artificial rainfalls, against which a numerical model is calibrated. Hydro-mechanical analysis is then conducted to estimate the factor of safety for expansive soil slopes with different pattern of fissures. A high slope inclination can increase the surface runoff, although the factor of safety decreases. It is of significance to minimize the amount of rainfall infiltration through desiccation cracks, since the increase in volumetric water content from rainfall events is more detrimental to reduce the unsaturated shear strength of soil. A conceptual framework is proposed to apply a drip irrigation system for expansive soil slopes. The volumetric water content can be maintained above a critical level to avoid the initiation of desiccation cracks. In the end, design parameters for the drip irrigation system are optimized.