The research of the mechanisms that trigger debris flow by surface runoff and upwelling ground water

• Main Authors: Po-Hsiang Chang, 張博翔
• Other Authors: Meei-Ling Lin
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/62770964689338781791

碩士 === 國立臺灣大學 === 土木工程學研究所 === 87 === Debris flow has been a severe slope instability problem in Taiwan over the years. Effective mitigation depends on understanding the mechanisms that trigger debris flow. Takahashi proposed that surface runoff is the primary factor causing debris flow, whereas Brand, Ellen, Sitar and Johnson proposed sudden increase in pore water pressure as the primary factor transforming unstable soil mass into debris flow. Rainfall, traditionally considered, saturates soil mass and increases pore water pressure by vertical infiltration, whereas Sitar et al. suggested that pore water pressure are associated with upwelling ground water from fragmentary bedrock. In this research, the boundary element method is used to establish numerical models based on tank experiments on different water supply systems to simulate debris flow generated by surface runoff and upwelling ground water by Wang (1994). Good agreement is achieved between numerical analysis and laboratory testing results. Meanwhile, the propagation in water pressure can be observed. In addition, the model can predict well presents free water surface rising phenomenon and water pressure distribution at various time intervals and locations in soil mass.