极端冰雪灾害条件下松散堆积体边坡演化分析

针对2008年初南方罕见的极端冰雪气候，为研究其与地质灾害的相关性，探讨了极端冰雪灾害条件下均质松散堆积体边坡的演化特征。比较了融雪与降雨触发滑坡的异同点，通过具体事例分析了融雪触发滑坡灾害的一般规律。引入度日因子与雪雨当量两个物理量，根据南方极端冰雪气候特征建立了简化的有效融雪模型，并从渗流场、稳定性及变形3个方面模拟计算在不同雨雪当量下均质松散堆积体坡体的演化特征。结果表明，一定的融雪速率与融雪量对松散堆积体边坡渗流场无影响。随着融雪的持续，非饱和区基质吸力逐渐减小，坡体整体稳定性逐渐降低。坡面上水平位移与竖向位移逐渐增大，表现为水平方向上前缘变形大于后缘，竖直方向上后缘下错与前缘隆起。在融雪持续一段时间后，坡体失稳破坏。

Evolution analysis of loose debris slope under condition of extreme snow hazard

In the beginning of 2008,South China encountered the rare extreme snow climate;and in this period many geological hazards happened.In order to study the correlation between the extreme snow climate and geological hazard,this paper explored the evolution characteristics of homogeneous loose debris slope in the condition of extreme snow hazard.The landslide triggered by snowmelt is compared with rainfall to obtain the similarities and differences and then the general law of snowmelt triggering landslide is analyzed through a specific example.Two physical quantities named degree-day factor and snow rainfall equivalent are used to establish the simplified effective snowmelt model based on the characteristics of extreme snow climate in Southern China.The evolution characteristics of the debris slope are simulated from seepage,stability and deformation under the different snow rainfall equivalent proposed above.The results show that a certain snowmelt rate and quantity have no influence on the seepage of the slope.With the snowmelt continuing,the metric suction in the unsaturated zone decreases gradually which causes the whole stability decreasing.The horizontal and vertical displacements of the slope surface increase gradually and the deformation of the front is larger than the back in the horizontal direction as well as the down dislocation in the back and protrusion in the front.After a time of snowmelt the slope fails and slides.