冰崩涌浪作用下的冰湖溃决过程试验研究

冰崩涌浪是导致冰湖溃决的一个主要的诱发因素之一。本文通过水槽模型试验，研究了在冰崩涌浪作用下，不同颗粒级配、坝高、下游坝坡坡度时冰碛坝的溃决过程，主要结论如下：（1）冰碛坝存在漫顶溃决、坝坡失稳、管涌破坏三种溃决模式；（2）根据冰崩涌浪的对坝体的侵蚀效应，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）；（3）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；（4）从动力学的角度提出了冰碛坝临界溃决条件的判定方法；（5）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（D50）呈现负相关关系。

Experimental Study on the Process of Glacial Lake Outburst under Surge Caused by Glacier Avalanches

Glacier avalanche surge is one of the main inducing factors leading to glacial lake outburst. Through the flume model test, this paper studies the process of moraine dam failure under the action of glacier avalanche surge with different grain-size distribution, dam height and downstream slope gradient. The main conclusions are as follows: (1) There are three modes of moraine dam failure: overtopping failure, dam slope instability, and piping failure; (2) 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 is divided into two stages: surge erosion stage (stage I) and small disturbance overflow erosion stage (stage II) in the reservoir area; (3) The strong hydrodynamic conditions after the surge passes the dam increase the erosion rate of the dam body. When the breach passes through, the surge has basically dissipated, and the breach process turns into a normal overflow failure, and the surge provides high-frequency transient load to the dam body, reducing the stability of the dam body; (4) From the point of view of dynamics, a method to determine the critical failure condition of moraine dam is proposed; (5) The peak discharge of glacial lake outburst is positively correlated with the dam height and downstream dam slope, and negatively correlated with the median particle size (D50) of the dam body.