Formation and characteristics of Guang'an Village landslide in Wuxi, Chongqing, China

摘要

At 00:20 on 21 October 2017, a large landslide occurred in Guang'an Village, Wuxi County, Chongqing, China. The overall length of the landslide was approximately 1500m, the width was approximately 1300m, the distribution area was approximately 1.95km(2), and the total volume was approximately 24.8 million m(3), with volume of the slipped area being approximately 6 million m(3). Nine people were reported missing after the landslide deposits accumulated in the riverbed of the Xixi River and blocked approximately 160m of the river, forming a dammed lake. We investigated the cause and mechanism of the initiation and development of the landslide using field investigations and on-site monitoring. The formation process of landslides can be divided into three stages: the start-up stage of the rock avalanche, the transportation stage, and the accumulation stage. In this case, the strength of the upper limestone was much greater than the strength of the lower shale. Under the effect of groundwater softening, the lower shale was plastically deformed with the combination of weak and hard lithologies, resulting in a rapid slip of the upper rock mass under gravity. After the slip of the rock mass in the source area, the rock mass of the lower slope was pushed downward. Then, the sliding mass moved from the source area pushing through the transportation area and formed the depositional area. There is still a possibility of further slip, so preventive measures must be taken as soon as possible to manage the potential slippage.