Breaching Characteristic Analysis of Landslide Dam Failure Experiment in Landao Creek

• Main Authors: Yi-Liang Chien, 簡依亮
• Other Authors: Su-Chin Chen
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/40942469275076467286

碩士 === 國立中興大學 === 水土保持學系所 === 104 === In recent year, the sediment disaster scale and hazard rating were increased with the climatic change, which raised the chance of landslide dam forming by blocked river. When landslide dam breached, large amount of floods burst out from the breach, which would result in significant damages and lost lives and properties of the residents. In this research, Landoa Creek Field-Scale Sediment Transport Experimental Station was used to conduct the global unique landslide dam failure experiment by control the sluice gate of Nengkao irrigational tunnel. To investigate the failure procedures and the characteristics of breaching, image process, hydrological monitoring, and the measurement of topography were combined. The experimental results were compared with the previous researches to clarify the real landslide dam failure process. According to the hydrological analyzing, landslide dam failure process could be divided into four important parts, and the influence factors were proposed. The water storage and dam subside period (Stage 1 and 2) were affected by inflow rate, impoundment volume, and the initial condition of the dam body. The head-cutting erosion period (Stage 3) was influenced by dam height and width. The breach varying and peak discharge period (Stage 4) was effected by the experimental scale. In this study, image process and analyzing are used to quantified the phenomenon of dam subside. The subsidence rate was 0.01 cm/s. The maximum value of dam subside was approximate 5 % of original dam height, which meant that the water storage period was decreased 8 %. In the other hand, Acoustic Doppler Current Profiler (ADCP) and pressure gauges were used to measure the erosion procedure of breach development. The vertical erosion rate of breach development was 0.86 cm/s, as a linear progress. The variation of the breach width was the key factor to control the outburst discharge. After landslide dam breaching, the downstream river morphology and topography were varied strongly by the breaching floods. Approximate 30% to 40 % of breach materials were deposited and formed sand bar in front of the landslide dam, which affected the river morphology in the future.