含砂水流之梳子壩撞擊力試驗分析

Abstract

目前國內對於梳子壩或防砂壩等防災構造物之設計在巨礫撞擊力考量方面，多半採用國外經驗公式，但經由文獻之回顧，各公式計算出之衝擊力差異性甚大，若計算出之衝擊力太大，會產生設計之工程構造物尺寸過大，甚不經濟，若公式計算出之衝擊力較小時，則可能有安全上之問題。 本研究目的為利用彈性體碰撞理論，推求出巨礫衝擊力之理論式為基礎，藉由實驗方式，以混合粒徑模擬土石流撞擊梳子壩，來修正推算出之衝擊力理論式，求得一個更符合實際撞擊情形之巨礫衝擊力計算式，期能對爾後梳子壩設計及土石流災害防治問題，提供一設計之參考。經由公式推導與試驗修正，得一巨礫衝擊力計算式，結果如下： F=30.8*U^1.2*R^2 式中： F為巨礫衝擊力(ton) U為巨礫速度(m/s) R為巨礫半徑(m) 關鍵字：梳子壩、彈性體碰撞理論、巨礫衝擊力

Currently, most of domestic designs of slit dam and check dam are based on foreign experiential formulas for the capability against boulders. From the literature reviews, we find great differences among the results of these formulas. If the impact force calculated is overvalued, the production will be too large in size and will not be economical. If the impact force calculated is insufficient, there may be hidden troubles of safety. In this research, we try to find a more practical formula for calculating the impact force of boulders. We infer an academic formula from the elastic collision theory. Then, in the experiments, we simulate the impact by debris flow with mixed diameters in order to correct the result formula. We hope we can provide a reference for future slit dam design and debris flow prevention. From the formula derivation and experiment correction, we have the following equation for calculating the impact force of boulder: F=30.8*U^1.2*R^2 In the equation, F is the impact force of boulder (ton) U is the speed of boulder (m/s) R is boulder’s diameter (m) Keywords: slit dam, elastic collision theory, impact force of boulder