梅里雪山1991年和2019年雪崩事件重建及影响因素分析北大核心CSCD

梅里雪山雪崩多发,但缺乏系统监测和研究。1991年1月3日梅里雪山发生了造成中日联合登山队17名队员遇难的巨大雪崩事件。2019年安装在明永冰川末端附近的物候相机拍摄到临近梅里雪山明永冰川的一次雪崩事件。两次事件类型不同,这对我们进行雪崩预测预警有良好的指示作用。本研究以RAMMS(Rapid Mass Movement System)模型为手段,利用经验值和经验公式确定影响模拟结果的主要模型参数和积雪可能断裂深度,在优化分析的基础上,对两次雪崩事件进行重建,定量分析雪崩堆积量、堆积范围等。结果显示:1991年雪崩共持续了192s,雪崩体从海拔5730m处断裂,沿坡面崩塌而下最终堆积在海拔约5000m的冰川粒雪盆地区,形成面积为0.6km^(2),体积约67×10^(4)m^(3)的堆积体。2019年雪崩共持续了158s,雪崩流最大高度35.91m,最大速度79.34m·s,堆积量76.2×10^(4)m^(3),雪崩堆积范围与野外观测到的一致。两次雪崩事件发生地位于雪崩极高危险区和高危险区,在一定程度上验证了风险评估的准确性。研究结果可为梅里雪山地区未来潜在雪崩灾害的风险评估提供依据,为雪崩预测预警提供良好的参考。

Reconstructing and analyzing avalanche events of 1991 and 2019 in Meili Snow Mountain

Snow avalanche refers to the phenomenon that the cohesion of the snow inside the slope is less than the gravity， and the friction force at the bottom is less than the shear stress， which makes it unstable slide and cause a large number of snow bodies to fall. Avalanches occur at uncertain times and can be extremely destructive when they destroy trees， sweep away roads and bridges， and destroy important infrastructure such as communications and electricity. Large-scale avalanches can also cause debris flow， landslides and other secondary disasters. The damage caused by an avalanche is incalculable and avalanches have seriously affected human productive activities and destroyed the natural environment. Therefore， snow avalanches are regarded as a serious natural disaster. Meili Snow Mountain is located in the monsoon maritime climate zone. Due to the difficult natural environment and lack of meteorological stations， there are few studies on snow avalanches， especially the necessary understanding of the reconstruction of the avalanche process. On January 3， 1991， 17 members of a Sino-Japanese mountaineering team were killed in an avalanche disaster at Meili Snow Mountain. On February 16， 2019， our field observation equipment recorded a large avalanche near the Mingyong glacier in Meili Snow Mountain. The avalanche generated a wave of air and destroyed the weather station at the end of the glacier. The trees in the path of the avalanche body were destroyed and the surrounding ecology suffered serious damage. To date， no detailed study of the avalanche process has been published. Only a good understanding and grasp of historical avalanche events can effectively avoid risks. Through the analysis of the two events， it is found that they belong to different avalanche types， which has a good indication for us to analyze the formation mechanism of avalanche， forecast and early warning. In this study， RAMMS （Rapid Mass Movement System） model was used as the main method. Firstly， the empirical values and empirical formulas were used to determine the avalanche fracture depth of the two avalanche events， and then the friction coefficient was determined by referring to the literature and model manual. On this basis， the two different avalanche disasters were reconstructed. Quantitative analysis of avalanche accumulation， range and maximum speed， et al. The simulation results show that： （1） In 1991， the avalanche lasted for 192 s. The avalanche broke at an altitude of 5 730 m， collapsed along the slope and finally accumulated in the flat area of 5 000 m above sea level， forming an accumulation body with an area of 0.6 km² and a volume of 67×10⁴ m³. The maximum height of the accumulation body was 13.46 m. The team’s camp 3 was completely submerged by the avalanche. The numerical simulation results show that the maximum height and velocity of avalanche flow are 16.98 m and 42.22 m·s^-1， respectively. （2） In 2019， the avalanche lasted for 158 s， the maximum height of avalanche flow was 35.91m， the maximum velocity was 79.34 m·s^-1， and the accumulation volume was 76.2×10⁴ m³. The range of avalanche accumulation was consistent with that observed in the field. （3） The two avalanche events occurred in the extremely high risk area of avalanche and high risk area， which verifies the accuracy of risk assessment to a certain extent. Field observation of snow properties and meteorological conditions can determine the cause and type of avalanches， while numerical simulation can analyze and reproduce avalanche dynamics. Based on the observed avalanche accumulation range， the numerical model can give quantitative results such as avalanche path， accumulation amount and movement speed through parameter calibration. On this basis， combined with the avalanche hazard zoning map and the overlay of the actual weather process， the avalanche disaster can be predicted at fixed points and the early warning information can be issued. Therefore， the RAMMS model is an effective tool for snow avalanche modeling and prediction， which can perform avalanche process reconstruction and hazard zoning well.