Influence of asynchronism between the spatial distribution of the hydraulic conductivity and shear strength parameters on the reliability assessment and failure mechanism of layered slopes

The spatial distributions of hydraulic conductivity and shear strength parameters are influenced by the soil structure, property and mineral composition. However, hydraulic conductivity is not only determined by the intrinsic soil property but also influenced by external factors such as fractures and interlayers. This study investigates the impact of the asynchronism between the spatial distribution of hydraulic conductivity and shear strength parameters on the reliability assessment and failure mechanism of unsaturated soil slopes with different titled stratifications under rainfall conditions. The results indicate that the asynchronism in the rotational angles (alpha) of hydraulic conductivity and shear strength parameters shows the greatest impact on the probability of failure (Pf) of slopes. By contrast, the asynchronism in the scales of fluctuation of hydraulic conductivity and shear strength parameters and employing different autocorrelation functions (ACFs) show minor impact on the Pf. The impact of using different ACFs, alpha, and scales of fluctuation to characterise the spatial variability of hydraulic conductivity on sliding mass and failure modes is minimal.