Numerical Simulation on the Landslide of an Unsaturated Soil Layer under Different Rainfall and Soil Conditions
| Autor: | Zong-YouWu, 吳宗祐 |
|---|---|
| Rok vydání: | 2017 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 105 Landslide is a general, natural geomorphic erosion process on hillsides and can be threaten to people’s life and properties. In this study, landsliding along an infinite slope for diverse soil materials were analyzed under different rain infiltration, and initial saturation conditions. We developed a model that describes landsliding (i.e., triggering and movement) based on the factor of safety and the Newton's second law. Evolution of capillary pressure within a soil layer obeys a dissipative wave equation and the Fourier’s series is employed into boundary conditions to describe time-varying, unsaturated rain infiltration. Factor of safety is used to determine the depth and timing of landslide triggering and the Newton's second law is solved by the classical Simpson’s rule. Results show that the intensity of rain infiltration controls the timing of the landslide occurrence, but landslide triggering is mainly influenced by accumulated rainfall infiltration and soil properties. Here we categorize 11 soil properties used in this study into stable and unstable hillslopes. Numerical results for the stable hillslope indicate that landslide could not be triggered when its corresponding soil materials containing silt more than 30% and clay more than 70%. For unstable hillslopes, failures in sand, loamy sand, and sandy loam can be from the top, gradually propagating to soil-bedrock boundary; however, that in sandy clay and loam is occurred at soil-bedrock boundary directly. Hyetographs of rain infiltration can play an important role in landslide triggering, showing that advanced peak and delayed peak can lead to early landslide occurrence and the significant terminal velocity of landslide movement, respectively. In addition, the timing of landslide occurrence and the terminal velocity of its movement are also governed by initial soil saturation, indicating that the higher the saturation, the earlier the timing of landslide triggering and the faster the terminal velocity of landslide movement. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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