不同體積濃度與堆積長度土石流撞擊力試驗

Abstract

本研究主要目的為研究不同情況下的土石流撞擊力。調配五種體積濃度 (30％、40％、50％、60％、70%)進行土石流撞擊試驗。分析體積濃度對撞擊力的影響，希望對未來構造物設計及土石流防治提供參考。另外，考慮連續豪雨時第一波土石流發生後，來不及清除壩前堆積土石時，第二波土石流接連發生之情形。設計壩前堆積長度0cm、20cm、25cm的礫石堆積，討論構造物在不同堆積情況下對土石流撞擊力之影響。 試驗結果發現撞擊力一開始隨體積濃度增加而增加，在體積濃度超過50%後因扮演潤滑劑角色的水份減少加上礫石量增加，土石流中的巨礫運動受阻礙且相互碰撞加劇而使體積濃增加撞擊力反而有下降的情形。而堆積長度方面，若堆積高度大於第一波土石流波高，則以壩前無堆積撞擊力最大，隨著堆積長度增加撞擊力減少。 本研究實驗設計錯誤，所以實驗結果有誤不足採信。

The purpose of this research is to investigate debris flow impact force under different situations. We mixed water and boulders in five kinds of volume concentration(30％、40％、50％、60％、70%) for debris flow impact force experiment. By analyzing the influence between volume concentration and impact force, we hope we can provide a reference for future structure design and debris flow prevention. Besides, consider continuous heavy rain, after the first debris flow occur and before the second debris flow occur, there is not enough time to clean out the deposition in front of dam, for this situation we design boulders deposition length by 0cm, 20cm and 25cm in front of dam, discuss the influence between different deposition in front of structure and debris flow impact force. After experiment and analysis, we found impact force increase with volume concentration, but over 50% impact force began to reduce. Because of water content reduce and boulder amount increase, boulder motion in debris flow was obstructed, collision increase, so when volume concentration increase the impact reduce on the contrary. For deposition length, if the height of deposition was higher than that of first debris, The max impact force occurred in 0cm deposition in front of dam and forces reduce when deposition is increase. This research was wrong in experiment design, so conclusions in this research cannot be use directly.