Distinct-Element Method Applied to The Landslide Evolution of Hungtsaiping Area
Date Issued
2007
Date
2007
Author(s)
Chang, Chia-Wei
DOI
zh-TW
Abstract
In 1999, a landslide took place at Hungtsaiping, Nantou, because of Chichi earthquake. By former researches, the landslide has several unique, such as few displacements in a large region, the different direction of displacement in different area, colluvium reactive slide and a curved slip surface, etc. The landslide behavior is different from custom, so it could be a topic for discussion.
The texture of colluvium at Hungtsaiping is related to the fractures of slide mass. Equally, the deposition of colluvium is related to the kinematics of landslide. These behaviors can not be analyzed by limit equilibrium method or continuum deformation analysis. Therefore, distinct-element method (DEM), which can discuss the separation of element and large deformation, is suitable to infer the landslide evolution of Hungtsaiping area.
In this study, we collect the geological and geomorphical data to set the landslide model. To investigate the mechanical behavior of material, the cores were used to conduct laboratory experiments. We use the Hoek-Brown failure criterion to represent the strength of the insitu rock mass with the intact rock strength obtained from laboratory experiments and the geological strength index (GSI). Finally, we use Particle Flow Code in 2 Dimension (PFC2D) to simulate the landslide kinematics of Hungtsaiping area in two events, old landslide and Chichi earthquake landslide.
The results show that the three zones of slide mass due to the sliding direction by former researches should be the same slide mass. In the major materials which compose the colluvium of Hungtsaiping, the sandstone rock mass has higher strength than that of shale rock mass may explain that the shale rock mass is prone to disintegrate after slide and the causes for the matrix as well as the granular supported colluviums. With some reasonable assumptions, we can reproduce the region and characteristics of colluvium in Hungtsaiping area before Chichi earthquake. It is possible to evaluate the similar displacement field to that with aerial photo by applying the strong ground motion of Chichi earthquake to the boundary of model.
Subjects
紅菜坪
崩積層
集集地震
地滑演化
Hungtsaiping
colluvium
Chichi earthquake
landslide evolution
Type
thesis
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