Abstract
A combined analysis involving a laboratory test and numerical modeling was performed to investigate the hydraulic processes leading to slope failure during rainfall. Through a laboratory landslide test in which artificial rainfall was applied to a homogeneous sandy slope, the timing and configurations of multiple slides were identified. In addition, volumetric water content was measured in real time through the use of monitoring sensors. The measured volumetric water content data were then used to validate the relevance of the numerical modeling results. The validated numerical modeling of the laboratory-scale slope failures provided insight into the hydraulic conditions that trigger landslides. According to the numerical modeling results, the miniaturized slope in the laboratory test was saturated in a manner so that the wetting front initially progresses downward and then the accumulated rainwater at the toe of the slope creates a water table that advances toward the crest. Furthermore, each of the five sequential failures that occurred during this experiment created slip surfaces where the pore-water pressure had achieved full saturation and an excessive pore-water pressure state. The findings of this study are expected to help understand the hydraulic prerequisites of landslide phenomena.
Highlights
Advances in Civil Engineering mechanisms according to slope shape [8] as well as studies on surface runoff and soil erosion according to rainfall characteristics [9]. e occurrence of slope failure under various slope conditions during rainfall was experimentally investigated by Acharya et al [10]; Gallage et al [11]; and Lourenco et al [12]
As 95 min elapsed after the beginning of the rainfall, a marginal failure was first observed at the toe of the slope as an initiator of four successive slope failures that occurred within 25 min (from Figures 6(a)–6(d)). e failure scale gradually expanded, and thereafter, with a long interim dormant period of 111 min, the largest and final slope collapse was recorded at the Drying Wetting van Genuchten
Iverson et al [13] found that changes in pore-water pressure exerted by changes in volume of the soil mass during sliding depend on the initial porosity and the relative time scales for soil deformation and porepressure diffusion. erefore, this initial porosity condition has been a pivotal factor in laboratory experiments for simulating debris flow mobilizations. Despite such possible dissimilarities from full-scale natural phenomena in terms of the stress conditions during sliding and postfailure behaviors, the laboratory experiment in this study is deemed validated as the scope of this study focuses on providing insight into comprehensive hydraulic processes “prior to” slope failures
Summary
In order to simulate rainfall-induced slope failures and the corresponding subsurface hydrologic processes, experiments were performed using a set of laboratory test apparatus. (3) In the model chamber, a sandy slope was formed with a steep angle to be failure-prone under rainfall. 5 e change in volumetric water content according to rainfall was measured and analyzed by the data management system in real time. 7 e real-time monitored data on volumetric water content were analyzed and compared to the numerical modeling results of rainfall seepage
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