FORMATION MECHANISM OF WANGSHAN-ZHUAKOUSHI LANDSLIDE IN EMEI CITY, SICHUAN PROVINCE

On June 14, 2015, an unstable slope in Xingyang village Jiuli town Ermeishan city begun to slide after continuous rainfall. It was named as Wangshan-zhuakousi landslide. It threatened more than 52 people and their property. It also caused a direct economic loss of about 5million RMB, and an indirect economic loss of more than 30million RMB. Due to timely and effective emergency evacuation by the local government organization, the landslide had no casualties. On the basis of field investigation and simulation calculation, the conclusions are as follows:(1)the landslide is belonged to the slip-cracking type. Its stability is governed by tuff interlayers. In meanwhile, the rock mass structure of landslide was crushed by the early mining excavation and 512 Wenchuan earthquake, which made the stability of landslide in critical condition.(2)Rainfall was the direct triggering factor of landslide formation. The rainfall mainly infiltrated the rock mass and became the groundwater which flowed along the tuff layer. With its weight increasing, stability coefficient of landslide was gradually reduced until high-speed landslide happened.(3)According to the characteristics of landslide in basalt area, the corresponding landslide emergency safety measures are summarizes.