不同拦挡结构对滑坡-碎屑流冲击和堆积特征的影响

The different retaining structures influenced on landslide-debris flow impact and accumulation characteristics

滑坡碎屑流是高位滑坡的一种常见运动形式,具有大规模、远程、高速的特点,在滑坡碎屑流运动路径上设置拦挡结构,可减小其致灾范围和致灾强度。文章运用三维离散元模拟软件,研究3种不同拦挡结构对滑坡碎屑运动和堆积特性的影响。研究结果表明:由于拦挡结构的作用,碎屑流颗粒的运动方向发生偏转,同时滑体的速度分布产生显著的变化-滑体最大速度从坡脚处变化到滑槽上颗粒的后缘。随着拦挡结构宽度的增加,法向力显著增大,切向力增加不显著;堆积区面积和最大水平运动距离不断减小,安全区的面积逐渐增加。本文引入无量纲数(Nk)分析颗粒分选效应对不同颗粒的运动和堆积特性的影响,相同拦挡宽度时,K3的Nk值最小,K1的Nk值最大;3种颗粒的Nk值随着拦挡结构宽度的增加逐渐增大。有拦挡结构时,碎屑流颗粒堆积体积百分比呈现指数函数分布,即随着运动距离的增大逐渐减小;无拦挡结构时,颗粒堆积体积的百分比呈现Extreme函数分布,即体积分布在中间位置附近取得峰值,向两侧呈递减趋势。

Landslide-debris flow is a common form of motion for high-level landslides. It has the characteristics of large scale, long runout distance, and high flow velocity. The deposit area of landslides and weaken the intensity of hazard could be reduced by the retaining structure. In this study, we used three-dimensional discrete element simulation software to study the accumulation and kinematic characteristics of debris flow with three different retaining structures. The results indicated that the movement direction of the debris flow particles is deflected and the velocity distribution of the sliding body changes significantly, which the maximum speed of the sliding body changes from the slope to the trailing edge. As the length of the retaining structure increases, the normal force increases significantly, and the tangential force increases slightly, the area of the stacking area and the maximum horizontal moving distance continue to decrease, and the area of the safe area continues to increase. Also, this paper introduced the dimensionless number ( N k ) to analyze the effect of particle sorting effect on the kinematic and accumulation characteristics of different particles. For the same intercept width, the N k value of K 3 is the smallest and the N k value of K 1 is the largest, the N k values of three particles gradually increase with the increase of the barrier structure width.After adding the resistive structure, the percentage of debris flow volume exhibits an exponential function distribution, and it decreases gradually with the increase of the moving distance;when there is no resistive structure, the percentage of the particle bulk volume exhibits the Extreme function distribution, that is, the volume distribution reaches the peak near the middle position, both sides show a decreasing trend.