Response of Step-Like Landslide to Pore-Water Pressure under the Action of Typhoon and Rainstorm

Abstract

Step-like landslides have been attracting more and more attentions because of their displacement with step-like characteristics. At present, there are few studies about the mechanism of a step-like landslide from the perspective of its response to pore-water pressure. This paper considers the Yaoshan landslide disaster mainly affected by rainfall and groundwater in Anxi County, Quanzhou City, Fujian Province, as an example. Based on an in situ monitoring test, we explored the infiltration pathways of typhoons and rainstorms, the main influencing factors, and characteristics of pore-water pressure and determined the relationship between landslide displacement and pore-water pressure in the study area. The results show the following: (1) the pore-water pressure within the slope varies with fluctuation in groundwater level which is influenced by vertical infiltration of rainwater through the slope surface and dominant channels in the study area. (2) The landslide exactly produces a step-like displacement when the pore-water pressure near the slip surface increases from the minimum point to the maximum and then dissipates to the vicinity of the starting point. (3) The correlation between pore-water pressure change and landslide displacement is revealed, and the empirical formula that can characterize slope displacement generated by increment in per unit of pore-water pressure in unit time has been proposed. This study is crucial as it offers important theoretical and practical significance for the analysis of disaster-causing mechanism and monitoring and early warning of the same type of landslide.