摘要
冰崩涌浪是导致冰湖溃决的一个主要的诱发因素之一。通过水槽模型试验,研究了在冰崩涌浪作用下,不同坝体颗粒级配、坝高、下游坝坡坡度对冰碛坝溃决过程的影响,揭示了涌浪对溃决过程的影响机制,并得到了冰碛坝溃决的临界条件。结果表明:冰碛坝存在漫顶溃决、坝坡失稳、管涌破坏3种溃决模式;根据冰崩涌浪对坝体的侵蚀效应,结合溃口的纵向演化过程,将冰碛坝的溃决过程划分为涌浪侵蚀阶段(阶段Ⅰ)、库区小扰动溢流侵蚀阶段(阶段Ⅱ);涌浪过坝后的强水动力条件增加了坝体的侵蚀率,当溃口贯通后,涌浪已基本消散,溃决过程转为正常的溢流溃决,并且涌浪向坝体提供了高频瞬时荷载,削减了坝体稳定性;从动力学的角度提出了冰碛坝临界溃决条件的判定方法;冰湖溃决洪峰流量与坝高和下游坝坡呈现正相关,与坝体中值粒径D_(50)呈现负相关关系。
Glacier avalanche surge is one of the main inducing factors leading to glacial lake outburst.The effects of different dam grain-size distributions,dam heights,and downstream slope gradients on the failure process of moraine dams under the action of ice avalanche surges were studied using flume model tests.The mechanism of the impact of surge waves on the failure process was revealed,and the critical condition for moraine dam failure was obtained.The results show that there are three modes of moraine dam failure of overtopping failure,dam slope instability,and piping failure.According to the erosion effect of glacier avalanche surge on the dam body and the longitudinal evolution process of the breach,the process of moraine dam failure can be divided into two stages of surge erosion stage(stage Ⅰ) and small disturbance overflow erosion stage(stage Ⅱ) in the reservoir area.The strong hydrodynamic conditions after the surge passing through the dam increase the erosion rate of the dam body.Once the breach is formed,the surge is basically dissipated and the breach process turns into a normal overflow failure.The surge also provides high-frequency transient load to the dam body,which reduces its stability.From the point of view of dynamics,a method to determine the critical failure condition of moraine dam is proposed.The peak discharge of glacial lake outburst is positively correlated with the dam height and downstream dam slope,while it is negatively correlated with the median particle size D_(50) of the dam body.
作者
阮合春
陈华勇
陈晓清
赵万玉
陈剑刚
李霄
俞昀晗
RUAN He-chun;CHEN Hua-yong;CHEN Xiao-qing;ZHAO Wan-yu;CHEN Jian-gang;LI Xiao;YU Yun-han(Key Laboratory of Mountain Hazards and Surface Processes,Chinese Academy of Sciences,Chengdu 610299,China;Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610299,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《科学技术与工程》
北大核心
2023年第29期12391-12398,共8页
Science Technology and Engineering
基金
第二次青藏高原综合科学考察研究(2019QZKK0904)
国家自然科学基金(U19A2049,U20A20112)
中国科学院“西部之光”人才培养计划(2020)。
关键词
冰崩涌浪
冰湖溃决
冰碛坝
洪峰流量
溃决过程
glacier avalanche surge
glacial lake outburst
moraine dam
peak discharge
breaching process
