Comparison of single- and dual-permeability models in simulating the unsaturated hydro-mechanical behavior in a rainfall-triggered landslide |
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| Authors: | Wei Shao Zongji Yang Junjun Ni Ye Su Wen Nie Xieyao Ma |
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| Institution: | 1.Key laboratory of Meteorological Disaster, Ministry of Education / Joint International Research Laboratory of Climate and Environment Change / Collaborative Innovation Centre on Forecast and Evaluation of Meteorological Disasters / School of Hydrology and Water Resources,Nanjing University of Information Science and Technology,Nanjing,China;2.Key Laboratory of Mountain Hazards and Surface Process,Institute of Mountain Hazards and Environment, Chinese Academy of Sciences,Chengdu,China;3.Department of Civil and Environmental Engineering,The Hong Kong University of Science and Technology,Clear Water Bay,Hong Kong SAR;4.Department of Physical Geography and Geoecology, Faculty of Science,Charles University,Prague,Czech Republic;5.Quanzhou Institute of Equipment Manufacturing,Haixi Institutes, Chinese Academy of Sciences,Quanzhou,China |
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| Abstract: | Landslide-prone slopes in earthquake-affected areas commonly feature heterogeneity and high permeability due to the presence of cracks and fissures that were caused by ground shaking. Landslide reactivation in heterogeneous slope may be affected by preferential flow that was commonly occurred under heavy rainfall. Current hydro-mechanical models that are based on a single-permeability model consider soil as a homogeneous continuum, which, however, cannot explicitly represent the hydraulic properties of heterogeneous soil. The present study adopted a dual-permeability model, using two Darcy-Richards equations to simulate the infiltration processes in both matrix and preferential flow domains. The hydrological results were integrated with an infinite slope stability approach, attempting to investigate the hydro-mechanical behavior. A coarse-textured unstable slope in an earthquake-affected area was chosen for conducting artificial rainfall experiment, and in the experiment slope, failure was triggered several times under heavy rainfall. The simulated hydro-mechanical results of both single- and dual-permeability model were compared with the measurements, including soil moisture content, pore water pressure, and slope stability conditions. Under high-intensity rainfall, the measured soil moisture and pore water pressure at 1-m depth showed faster hydrological response than its simulations, which can be regarded as a typical evidence of preferential flow. We found the dual-permeability model substantially improved the quantification of hydro-mechanical processes. Such improvement could assist in obtaining more reliable landslide-triggering predication. In the light of the implementation of a dual-permeability model for slope stability analysis, a more flexible and robust early warning system for shallow landslides hazard in coarse-textured slopes could be provided. |
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