强震触发大型滑坡抛石运动特征研究

大光包滑坡是2008汶川地震触发的最大滑坡。滑坡位于四川省绵阳市安县高川乡,与汶川地震发震断裂直线距离5 km,滑坡最大长度4.6 km、最大高差0.73 km、规模近12亿m~3,改变了近10 km~2地形地貌。大光包滑坡除了具有超强动力与远程运动特征外,还表现出大规模块石高速抛射现象。在对大光包滑坡边界特征、运动和堆积特征分析基础上,研究了大光包滑坡抛石运动特征。结果表明:大光包滑坡抛石发生在滑坡南侧滑体,堆积于门槛石沟;坡体结构、大光包滑坡主滑体与对岸山梁相撞后产生的"刹车效应",以及门槛石沟开阔地形为抛石产生提供了条件;理论计算得出抛石速度平均值为99 m/s。

Study on flying rock movement characteristics of large landslide induced by earthquake

Daguangbao landslide, the largest landslide triggered by Wenchuan earthquake in 2008, is located in Gaochuan Township, Anxian County, Mianyang City, Sichuan Province. It is 5 km away from the Wenchuan earthquake causative fault. The maximum length of the landslide is 4.6 km with maximum elevation difference of 0.73 km and a scale nearly of 12×108 m3, and had changed the landform of the ambient region about 10 km2. In addition to the characteristics of high speed and long runout, Daguangbao landslide also showed the phenomenon of large-scale flying rock in high speed. Based on investigations of the failure boundary, motion and deposition of the Daguangbao landslide, the block rock movement characteristics was studied. The results showed that the rock flying occurred in the south-side sliding body of the landslide and was accumulated in Menkanshi gully. The slope body structure, the "brake effect" due to the collision of the main sliding body of the landslide and the opposite mountain ridge and the open terrain of Menkanshi gully all provided the condition for the rock flying. The calculated flying velocity of the block rock was 99 m/s.