Dynamic analysis and field investigation of a fluidized landslide in Guanling, Guizhou, China

On June 28, 2010, a large catastrophic landslide was triggered by a heavy rainfall in Guanling, Guizhou, China. This catastrophic event destroyed two villages and caused 99 casualties. The landslide involved the failure of about 985,000 m3 of sandstone from the source area. The displaced materials traveled about 1300 m with a descent of about 400 m, covering an area of 129,000 m2 with the final volume being accumulated to be 1,840,000 m3, approximately. To provide information for hazard zonation of similar type of landslides in the same area, we used a dynamic model (DAN3D) to simulate the runout behavior of the displaced landslide materials, and found that a combined frictional–Vollemy model could provide the best performance in simulating this landslide and the runout is precisely duplicated with a dynamic friction angle (ϕ) of 30° and a pore pressure ratio (ru) of 0.55 for the materials at the source area and with Vollemy parameters of friction coefficient f = 0.1 (dimensionless) and turbulent coefficient ξ = 400 m/s2. The simulated results indicated that the duration of the movement is estimated at about 60 s for a mean velocity 23 m/s. To examine the effectiveness of simulation by means of DAN3D and also to evaluate the reactivation potential of these displaced landslide materials depositing on the valley, we used electrical resistivity tomography (ERT) method to survey the depth and internal structure of landslide deposits. The ERT results showed that DAN3D gave a good prediction on the shape and runout distance of the landslide deposits, although the predicted maximum depths of landslide deposit on some areas were differing from those obtained by ERT method.