冰湖溃决会引发突发性洪水与泥石流，直接冲毁下游基础设施、威胁生命财产安全，并破坏生态环境，探明冰湖溃决机制对灾害预警及防治至关重要。冰碛坝作为溃决过程中的关键天然屏障，其表层“铠甲层”直接决定了冰碛坝的抗侵蚀能力与整体稳定性。为研究冰碛坝铠甲层表面大块石的起动机理，以西藏别隆措冰碛湖为原型，通过水槽试验探明块石起动的关键机制。基于大块石在涌浪下以滚动起动为主的观测事实，建立了考虑附加力与上覆推力的滚动起动流速公式。结果表明：块石在涌浪作用下的起动过程可分为单颗粒滑移或滚动、局部动态失稳及整体溃决式起动3 种模式，且起动行为与冰崩涌浪规模、块石粒径、容重、暴露度以及坝坡坡度等因素密切相关。铠甲层块石起动流速公式实用性好，解决了传统公式忽略颗粒形状差异、采用平槽泥沙推导并将块石简化为均质球体等与实际情况不符的问题。该计算模型能够较准确地预测起动流速，可用于分析冰碛坝铠甲层块石在涌浪等水流作用下的起动问题。未来研究应聚焦冰碛坝铠甲层的失稳机制，通过试验、野外观测与数值模拟揭示其在水力与冻融作用下的破坏阈值，建立耦合该过程的溃决动力学模型，发展基于结构状态的预警方法。

Abstract：Glacial lake outburst floods represent a classic chain-reaction disaster in high-mountain regions, frequently triggering sudden floods and debris flows that severely threaten downstream infrastructure and ecological security. Against the backdrop of global warming and ongoing glacial retreat, the frequency and scale of such disasters are increasing, yet the underlying mechanisms and dynamic processes remain incompletely understood. Deepening our understanding of glacial lake outburst flood mechanisms and evolutionary patterns not only enhances regional disaster warning and risk prevention capabilities but also provides crucial scientific insights into catastrophic processes within mountainous systems under climate change. As the key natural barrier during outbursts, the surface “armor layer” of morainic dams directly determines the dam's erosion resistance and overall stability. To investigate the initiation mechanism of large boulders on the armor layer of glacial moraines, the Bielong Co glacial lake in Xizang was used as a prototype. Water channel experiments were conducted to clarify the key mechanisms of boulder initiation. Based on observations showing that large boulders primarily initiate movement through rolling under surge waves, a rolling initiation velocity formula was established, accounting for additional forces and overburden thrust. Results indicate that the initiation process of boulders under surge waves can be categorized into three modes: single-particle sliding or rolling, localized dynamic instability, and overall catastrophic initiation. The initiation behavior is closely related to factors such as the scale of the ice avalanche surge wave, boulder grain size, bulk density, exposure degree, and dam slope gradient. The initiation velocity formula for armor layer boulders demonstrates high practicality, addressing shortcomings of traditional formulas that neglect particle shape variations, rely on flat-channel sediment dynamics derivations, and simplify boulders as homogeneous spheres, approaches inconsistent with reality. This computational model accurately predicts initiation velocities and can be applied to analyze the initiation of armor layer boulders in glacial till dams under surge wave and other flow conditions. Future research should focus on the microstructural characteristics and initiation mechanisms of the armor layer. By integrating field observations, experimental simulations, and numerical analysis, it is essential to systematically investigate its mechanical response and progressive failure process under sustained seepage, water level fluctuations, and freeze-thaw cycles, with particular emphasis on revealing the governing principles of armor layer shear strength and permeability stability controlled by particle gradation, cementation degree, and structural integrity, and elucidating the dynamic thresholds from localized erosion to overall failure. Building on these findings, we develop a coupled dynamic model that simulates the entire ice-lake outburst process, incorporating the initiation mechanism of the armor layer. This work advances a dynamic disaster risk assessment system based on real-time monitoring of dam structural conditions and multi-parameter early warning indicators. Consequently, it provides critical theoretical support and scientific tools for precise early warning and risk prevention of ice lake outbursts.