不同断面泄流槽的堰塞坝溃决模型试验研究

Experimental Study on Collapse Models of Landslide Dam with Different Cross-Section Discharge Troughs

以2018年“11·3”金沙江白格滑坡堰塞坝为原型,对所布设的泄流槽从断面形状、位置、尺寸等方面进行考虑,采用相同颗粒级配材料,设置7种试验工况,在控制上游来水量相同条件下,对各工况下试验溃决过程进行观察,进而揭示堰塞坝溃决演变机理及其影响因素。结果表明:溃决过程可分为初始孕育阶段、溯源坡面侵蚀阶段、溯源陡坎侵蚀阶段、河床稳定平衡阶段4个阶段;不同断面形状泄流槽的溃决过程中,冲蚀程度影响范围由强到弱排序为自然组、三角形槽、矩形槽、梯形槽。对于泄流槽断面形状尺寸及位置,当宽度相同且深度较低时,受约束影响溃决过程会较为提前;当泄流槽断面一致,布设位置位于一侧时,受一侧固定约束影响,溃口宽度扩展会小于布设位置位于中间的情况。研究结果可为堰塞坝溃决机理分析及堰塞坝应急救援处置提供参考。

Taking the Jinsha River Baige landslide dam on November 3,2018 as a prototype,the same particle grading material was used,and 7 kinds of test conditions were set up,which considered the cross-sectional shape,position,size,and other aspects of the installed discharge troughs.Under the same condition of controlling the upstream water inflow,the experimental breaching process under each condition was observed to reveal the evolution mechanism of landslide dam breaching and its influencing factors.The results show that the breaching process can be divided into four stages:the initial gestation stage,the erosion stage of the backwater slope,the erosion stage of the backwater steep bank,and the stable equilibrium stage of the riverbed.During the breaching process of different cross-sectional shapes of discharge troughs,the impact range of erosion degree is ranked from strong to weak as natural group,triangular groove,rectangular groove,and trapezoidal groove.For the cross-sectional shape and size as well as the location of the discharge trough,when the width is the same and the depth is lower,the breaching process will be earlier under the influence of the constraints;when the section of the discharge trough is the same and the layout is located on one side,under the influence of the fixed constraints on one side,the breaching width expansion will be smaller than that when the layout is located at the center.The research results can provide a reference for the analysis of failure mechanism and emergency rescue and disposal of landslide dam.