漫坝水流条件下宽级配土石料冲刷特性试验研究  

Experimental study on scouring characteristics of wide graded earth material in overtopping flow

作　　者：赵天龙[1] 付长静[1,2] 马廷森 张川 ZHAO Tianlong;FU Changjing;MA Tingsen;ZHANG Chuan(National Inland Waterway Regulation Engineering Research Center,Chongqing Jiaotong University,Chongqing 400074,China;Geotechnical Engineering Deportment,Nanjing Hydraulic Research Institute,Nanjing 210029,China;Qinghai Water Resources and Hydropower Survey,Planning,Design and Research Institute Co,Ltd,Xining 810001,China)

机构地区：[1]重庆交通大学国家内河航道整治工程技术研究中心,重庆400074 [2]南京水利科学研究院岩土工程研究所,江苏南京210029 [3]青海省水利水电勘测规划设计研究院有限公司,青海西宁810001

出　　处：《人民长江》2023年第1期212-219,232,共9页Yangtze River

基　　金：国家自然科学基金项目(52279095,52109149);重庆市科委基础研究与前沿探索项目(cstc2021jcyj-msxmX0155);水利部土石坝破坏机理与防控技术重点实验室开放基金项目(YK319006);港口航道泥沙工程交通行业重点实验室开放基金项目(YK220001-6)。

摘　　要：堰塞坝漫顶溃坝过程本质上是漫坝水流与坝体溃口处土体颗粒之间的相互作用过程,针对该作用机制开展专门研究,对于清楚揭示堰塞坝宏观溃决机理具有指导意义。针对堰塞坝漫顶溃坝过程中水流的强非恒定特征及坝料的宽级配特性,开展了不同水流条件下的宽级配土石料冲刷特性试验研究。研究结果表明:窄级配或均匀土石料的冲刷过程宏观上表现为沙波的形成、移动,也是推移质运动的主要形式,而宽级配土石料冲刷过程以冲刷坑的形成、扩展、移动为主。宽级配土石料在弱非恒定流条件下,粗颗粒对细颗粒的包围、遮蔽效应明显,抗冲蚀性能较强,而在强非恒定流条件下,粗颗粒背水面容易发生临空并起动,抗冲蚀性能相对较弱。宽级配土石料冲刷初期以坡角垮塌破坏为主,后期则主要体现为溯源冲刷。因此冲刷初期下游冲刷强度较高,上游冲刷强度较弱,床面容易形成倾向于下游的坡面且坡角逐渐增大;后期床沙在溯源冲刷作用下,上游部分粗颗粒间歇性起动并停止于下游,在其遮蔽作用下冲刷段下游容易形成细颗粒堆积区,使坡面倾角逐渐减小。因此,堰塞坝溃坝过程计算时应当充分考虑溃口底坡的倾角变化过程。非恒定流条件下的冲刷强度要大于恒定流条件下,基于恒定水流条件下所建立的输沙公式并不能用于精确的溃坝过程计算。In essence,the barrier dam overtopping process is an interaction process between flow and soil particles at the breach.Study on this mechanism is of great significance to clearly revealing the macro collapse mechanism of barrier dams.Therefore,aiming at the strong nonlinear features of overtopping flow and the wide graded features of dam earth materials,our experimental study on the scouring characteristics of wide graded earth materials under different water flow conditions was conducted.The results show that scouring process of narrow graded or uniform earth materials is macroscopically represented by the formation and movement of sand wave,which is also the main movement form of bed load.The scouring process of wide graded earth material is mainly in a pattern of formation,expansion and movement of scouring pit.For wide graded earth material under weak unsteady flow,the surrounding and shielding effect of coarse particles on fine particles is obvious,so the erosion resistance is strong.In contrast,under strong unsteady flow,the back of coarse particles is hollow and the particle is prone to move,so the erosion resistance is relatively weak.The erosion of wide graded earth materials is mainly collapse of downstream slope in the initial stage,and is transformed to backward to source erosion at the later stage.Therefore,in the initial stage of erosion,the downstream erosion intensity is high,the upstream erosion intensity is relatively weak,and the bed surface is easy to form a slope inclined to the downstream,and the slope angle gradually increases.In the later stage,under the action of backward to source erosion,some upstream coarse particles start intermittently and deposit in the downstream.Under the shielding effect,the downstream of the scouring section is easy to form an accumulation area,which gradually reduces the slope angle.This evolution process of the bottom slope angle at the breach should be fully considered in the calculation of barrier dam failure.The scouring intensity of unsteady flow is greate

关 键 词：堰塞坝 漫坝水流 宽级配 冲刷机理 非恒定流 

分 类 号：TV65[水利工程—水利水电工程]