西藏终碛湖溃决形式研究

A study of the outburst form of the end-moraine lake in Tibet

西藏终碛湖众多,一旦发生溃决,将造成巨大损失。冰湖溃决机制的研究对冰湖溃决预测和溃后灾害评估是十分必要的。将冰湖终碛堤视为天然堆石坝,用水力学和土力学理论研究冰湖溃决的力学机制。重点研究溢流型溃决形式和管涌型溃决形式,根据野外观测数据和前人的研究,发现溢流型溃决的溃口多呈梯形或圆弧状形,对比真实数据发现溃口顶宽与坝高的关系,并且所有冰川终碛堤都表现为局部溃决。通过实地考察、取样分析,判断光谢措终碛堤的可能渗透破坏形式。

Many end-moraine lakes are distributed in Tibet. Once any of theses lakes outbursts, this region will undergo a huge loss. So studying the outburst mechanism is essential for forecast and assessment of the disaster. In this paper, the end-moraine dam is considered as a natural dam and the outburst of end-moraine lake is researched in terms of hydraulics and soil mechanics. According to field observations and previous researches, our study focuses on the overflow and piping-break types of outburst. It is found that the dyke breach in the overflow type usually has the shape of an are or a trapezoid. From the field observations, we have found a relationship between the height and the open width of the breach. Almost all end-moraine lakes collapse partially. Based on field surveys and sampling analysis, we have determined the possible ways of collapse of the Guangxieco end-moraine lake by infiltration.