Analysis On Stability And Formation Mechanism Of The Donghekou Landslide In Qingchuan County, Sichuan Province

The Donghekou landslide which is located in Qingchuan County, Sichuan Province, was triggered by the “5.12” Wenchuan earthquake, and destroyed the entire Donghekou village. The disaster caused a great loss of lives and properties. By conducting a thorough review on previous studies, field investigations, remote sensing interpretations and engineering drilling in this study, the objective of this thesis is to analyze and improve the current understanding on the morphological characteristics, formation and movement mechanismsof the Donghekou landslide. A three-dimensional geological model of the Donghekou landslide before and after the earthquake were establishedbased on the field investigation, which wereused in the numerical simulation to analyze the static and dynamic stability of the landslide in multi-scenarios. Thegeological conditions of landslide area was hypothetically reproduced, and then was used to predict the deformations of the current Donghekou landslide under the possible earthquake and rainfall conditions in the future. The primary conclusions obtained from this study mainly include:(1) The formation and triggering mechanism of the Donghekou landslide. Under the influence of earthquake loadings, the upper portion of the Donghekou landslide starts moving from its in-situ place, and sliding downward along the slip surface.The moving portion falls apart during the sliding process, and causes a barrier lake in the Qingzhu river.(2) The factors of safety of the Donghekou landslide equal to 1.9 and 2.33 before and after the “5.12” earthquake. Based on the numerical simulation results, the large deformation and damage occurred on the upper portion near the fault boundary, with the fault weak zone, displacement of rock and soil were in different directions.(3) The predominant factors affecting the stability of the Donghekou landslide. The strength parameters of the fault activity and rock, rainfall characteristics The inertia force of fault movement have a certain guiding role in main sliding direction.