窗口坝是常用泥石流拦挡坝之一,其泥砂粒径调节能力是窗口坝设计的主要考虑因素,也是目前急需解决的基本问题。通过试验对窗口坝拦截不同性质泥石流的泥砂粒径调节功能进行了探讨,初步研究结果表明:窗口坝具有一定拦粗排细功能,拦粗排细效果对黏性泥石流最差;提出了临界粒径的概念并给出了临界粒径变化范围;临界粒径的大小与变化范围受泥石流性质和窗口坝闭塞类型(全闭塞、部分闭塞、不闭塞)的影响;就同一坝而言,拦截泥砂的临界粒径随泥石流密度增加而增大。

Window-frame dam is a common measure in debris flow prevention engineering. The function of changing sediment size distribution is one of the main factors in the design of window-frame dam, and is also an urgent issue to be solved. In order to improve the design methods, we conduct a series of experiments to research the function of changing sediment size distribution of window-frame dam. Results show that 1) window-frame dam has a function of trapping coarse sand and discharging fine sand, and this function has a worst performance for viscous debris flow compared with trapping sub-viscous and intermediate debris flow; 2) we put forward the concept of critical particle size for the first time and give a variation range of critical particle; 3) the critical particle size and its variation range were affected by the density of debris flow and the type of window-frame dam (totally blocked, partially blocked, and open dams); 4) the critical particle size increases with the increase of density of debris flow for the same window-frame dam.