Poro-mechanical coupling influences on potential for rainfall-induced shallow landslides in unsaturated soils

• An analytical solution to coupled infiltration into an infinite unsaturated soil slope is obtained using a Laplace transform-based method.
• The analytical solution is able to analyze the coupling effect and consider the influence of time-dependency on the estimation of Fs.
• The poro-mechanical coupling of water infiltration and deformation play an important role in the stability of the infinite unsaturated slope.

Rainfall-induced landslides are a common occurrence in terrain with steep topography and soils that have degradable strength. Rainfall infiltration into a partially saturated slope of infinite extent can lead to either a decrease or complete elimination of soil suction, compromising the slopes' stability. In this research the rainfall infiltration coupled with deformation of a partially saturated soil slope during rainfall infiltration is analyzed. The limit equilibrium conditions and the shear strength relationship of a partially saturated soil are employed to develop an analytical solution for calculating the stability of an infinite partially saturated slope due to rainfall infiltration. The analytical solutions are able to consider the influence of the coupled effects on the stability of the slope. The factors that affect the safety of a partially saturated slope of infinite extent are discussed. The results indicate that the poro-mechanical coupling of water infiltration and deformation has an important effect on the stability of the infinite unsaturated slope.