甘肃舟曲县2019年“7·19”牙豁口滑坡复活成因及机理

Cause for and mechanism of the reactivation of Yahuokou landslide in Zhouqu County, Gansu Province

通过区域地质调查、无人机测绘以及工程地质勘探,结合降水数据、地面全球导航卫星系统监测形变数据和电阻率成像数据,对2019年"7·19"舟曲牙豁口滑坡特征、复活成因、变形模式和机理进行分析.发现本次滑动为大型推移式断裂带堆积层滑坡的复活,滑坡体近年来一直处于蠕滑变形状态;滑坡活动受多因素影响,软弱的岩土体、地质构造、有利的地形等因素是导致此次复活的内部因素;崩塌体的加载、地下水的富集是滑坡复活的外部因素,前期持续的降雨是诱发滑坡的主要原因;滑坡体的变形模式为逐级加载、逐级传递应力、逐级启动的缓变推移式变形;变形破坏方式为蠕滑-拉裂-土石流模式.在未来强降雨条件下,仍然存在滑动堵断岷江形成堰塞湖的风险,应选择抗滑桩+排水孔的组合工程对上级块体进行治理,同时要减少下级块体上的工程活动.

A combination of geological survey and advanced techniques of unmanned aerial vehicle mapping, global navigation satellite system monitoring, and electrical resistivity tomography were used to systematically study the morphological characteristics and reactivation mechanism of the "7·19" Yahuokou landslide and it was found that the landslide was a reactive slide of an accumulation of ancient landslides along the fault region and had been in a creep deformation state in recent years. The weakness of rock and soil, and its geological structure were the main internal causes for the revival of the landslide;the loading of the collapsed body and enrichment of groundwater the external factors leading to the landslide while a continuous rainfall in the early stage directly induced the landslide. It could be concluded that thedeformation mode was activated step by step by the gradual loading and gradual stress transfer. The type of failure was the result of a combination of creep, tension crack and earth rock flow. There were potential risks of landslides-blocking river-barrier lake and flood under the future condition of a heavy rainfall.Anti-slide piles with drainage holes could be used as an effective mitigation strategy against the upper block sliding along with a prohibition of engineering activities on the lower part of the slide.