沥青混凝土心墙坝漫顶溃坝试验与溃坝过程数值模拟

Model tests and numerical simulation of overtopping-induced breach process of asphalt concrete core dams

基于中国新疆射月沟水库溃坝案例资料,在水槽冲蚀试验系统进行了沥青混凝土心墙坝漫顶溃坝试验,直观展现了坝壳料冲蚀与心墙折断过程,发现了抗冲蚀能力强的沥青混凝土心墙对溃坝过程的重要影响。将沥青混凝土心墙坝的漫顶溃坝过程分为3个阶段:坝壳料溯源冲蚀至沥青混凝土心墙裸露;心墙第一次折断,溃口流量迅速增大并出现峰值;心墙发生多次折断直至溃口稳定。在试验成果的基础上建立了模拟溃口流量和溃口形态演化的沥青混凝土心墙坝漫顶溃坝过程数学模型,模型的特色在于通过冲蚀公式模拟沥青混凝土心墙的裸露长度,采用力矩平衡法计算裸露心墙的折断时刻、折断长度和折断次数,从而合理反映了沥青混凝土心墙坝漫顶溃坝时坝壳料与心墙的耦合作用机制。采用建立的数学模型对射月沟溃坝过程进行了反演分析,计算结果表明重要溃坝参数与实测值误差均在±25%以内,较好地反映了溃坝过程,研究成果可为沥青混凝土心墙坝漫顶溃坝过程模拟提供借鉴。

Based on the dam breach case data of Sheyuegou Reservoir in Xinjiang Autonomous Region of China,the model tests on overtopping-induced breach of asphalt concrete core dams are conducted in the flume erosion model test system,and the process of erosion of dam shell materials and bending of core walls is visually demonstrated.It is found that the asphalt concrete core with strong erosion resistance has important influences on dam breach process.The breach process of asphalt concrete core dams due to overtopping can be divided into three stages:retrogressive erosion of dam shell materials,the first fracture of asphalt concrete core until the occurrence of the peak flows,occurrence of multiple fractures of core wall until the stabilization of the breach morphology.Based on the breach model test results,a mathematical model is developed to simulate the breach flow discharge and the breach morphology evolution of asphalt concrete core dams due to overtopping.The highlights of the model are the simulation of the exposed length of asphalt concrete core by soil erosion formula,and the calculation of breaking time,breaking length,and number of breaking time of the exposed core wall by the moment balance method.Therefore,the coupling mechanism between dam shell materials and core wall of asphalt concrete core dams can be reflected reasonably during dam breaching.The mathematical model is used to conduct back analysis of the dam breach process of Sheyuegou Reservoir,and the calculated results show that the relative errors of important breaching parameters are within±25%,which gives a good perfomance in dam breach modeling.The research results can provide reference for simulation of breach process of overtopping-induced asphalt concrete core dams.