The Basic Characteristics and Failure Mechanism of Guizhaoshou High-speed Landslide

摘要

Wenchuan Mw 7.9 earthquake triggered more than 60,000 landslides over a broad area, and caused huge economic losses.Although the Wenchuan earthquake has passed for five years, it should deserve attentions in the regions that there are a lot of potential unstable slopes with loose rock mass structure, high hazards and difficult to be recognized.These unstable slopes easily transfer to landslides and cause casualties and property losses after it experienced several heavy rainstorms.Guizhaoshou landslide is located in Pengzhou city, the high intensity area of the Wenchuan earthquake.It is a rainstorm-triggered high-speed landslide after four years of Wenchuan earthquake.Some studies have been done on this landslide, this paper presents some results mainly on:(1) the features of the main slide body and accumulation zone(Ⅰ, Ⅱ ,Ⅲ);(2) Six factors affecting the stability of the landslide and triggered landslides, including rugged topography, formation lithology, the slope toe under cutted by rivers and debris flow, faults effect, human engineering activities and heavy rainstorm which is the major inducing factors to landslide;(3) landslide failure mode which is defined as the slip-projectile mode with the initial projectile velocity of 40.41m/s, and runout distance of 137 meters;(4) the destruction process of Guizhaoshou landslide including four stages such as slope cumulative failure, slope ejecting, slope body movement, and slope accumulating;(5) The differences between rainstorm-triggered and earthquake-triggered rapid landslide.After the "5.12"earthquake, domestic and foreign researches have focused on the rapid and long-runout landslide triggered by ground strong motion by earthquake and acquired many results.But there are very few studies on rapid landslide triggered by rainstorm.This paper enriches the research on the rainstorm-triggered rapid landslide and has a certain reference value for the disaster prevention and mitigation work in the areas threatened by seismic geohazards.