Comparison of Landslide Dam Overtopping Failure for Field and Laboratory Experiment

• Main Authors: Tzu-Yang Hsu, 徐子陽
• Other Authors: Su-Chin Chen
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/29329292081639337615

碩士 === 國立中興大學 === 水土保持學系所 === 101 === Due to the extreme climate, torrential rain cause Taiwan a lot of landslide and debris flow events, even turning into landslide dam collapse disaster. Research of the dammed lake mostly based on site investigation after disaster, laboratory experiment and numerical simulation. But they are still not precise for scene reoccurrence. This study used cameras and water level sensors for practicing field experiment of landslide dam overtopping failure in Landao creek, Huisun experimental forest. Laboratory experiment was also exceeded for supplying the insufficiency of field experiment in order to get accurate understanding of dammed lake disaster. On the basis of laboratory experiment, ascendant and descendent of water level variation in landslide dam are the same, indicate that inflow and outflow rate are the same. Because of the seepage, landslide dam start failing from downstream dam toe, and the shape turning into triangle from regular trapezoid. Water surface is higher than the dam after overtopping, and the gap increase with time due to flow force. According to the field experiment results, no matter whether the dammed lake is filling or out breach, water velocity is inversely proportional to time, and so is the outflow discharge. Breach development can be divided into degradation and expander. Under usual circumstances, degradation quantity is larger than the expander, due to the water force and flow direction. The strong flood induced by the dam failure would create a new flow path, and the river wide would increase from upstream to downstream, but the slope does opposite. If the seepage is small, the process of landslide dam failure is really quick, and vice versa. The procedure of breach development is always from V type to U type. Destruction of landslide dam is related to sediment composition and consolidation of the dam.