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.