Deformation characteristics and mechanism of the landslide in West Open-Pit Mine, Fushun, China

The West Open-Pit mine in Fushun, NE China is currently the largest open-pit coal mine in Asia. A serious problem of slope instability has developed and is worsening. Several studies have investigated the northern slope instability, while little attention has been paid to the stability problem on the southern slope which faces northwards into the mine. Recent monitoring data show continuous deformation of the southern slope, which is a serious threat to the safe operation of the mine. In this paper, we study the deformation characteristics and mechanism of the landslide on the southern slope of the West Open-Pit mine. Our results show large deformation of the partial surface of the landslide, deep rock mass sliding, and clear sliding surface dislocation characteristics. The southern slope is a bedding rock slope with a weak interlayer. There are two faults in the study area, and the development of joint fissures promotes the internal mechanism of the landslide. The safety factor of the southern slope has decreased with the deepening of the open-pit, which shows that excavation unloading was a main triggering factor for the landslide. The mining is stripping rock mass from the bottom of the open-pit, cutting the foot of the slope and causing the rock mass to lose support. The downslide force caused by the gravity stress of the slope becomes greater than the shear strength of the weak interlayer, causing the slip body to undergo bedding slide and continuous deformation.