This paper presents the use of the discontinuum approach based on the Discontinuous Deformation Analysis (DDA) for the modeling of granular debris flows which are found to be the major type of the debris flow in Taiwan. Differing from the conventional continuum-based method which lacks of the mechanics for describing the behavior of the stony debris flow or the granular flow, our proposed method based on DDA is capable of exploring the initiation and mechanism of the granular debris flow to further understand the debris flow behavior. In addition, the incorporation of the effects of fluid flow into the DDA for establishing the methodology and code is presented in this study. Results obtained demonstrate that the proposed method can be a useful tool to model the initiation and mechanism of the granular debris flow based on the discontinuum mechanics with emphasis on the particle mechanics for more realistically studying the debris flow problem.


Occasional rainfall, steep relief, and adequate debris flow materials are three major components to form a debris flow event in a potential debris-flow creek. The topographic, geological and hydrologic characteristics of Taiwan are corresponding to the three components of occurrence of debris flows. Taiwan is, therefore, frequently beset by debris flow problems during typhoon and heavy rainfall. These fastmoving flows accompanying mud and rock are capable of destroying houses and lives, washing out roads and bridges, or obstructing streams and roadways. It is widely recognized that most shallow landslides in Taiwan occurred as a result of heavy rainfall and consequent pore pressure increases in the near subsurface. Historically typhoon events with high-intensity, long-duration rainfall often triggered shallow, rapidly moving landslides, i.e. debris flows, resulting in casualties and property damage in the past decades.

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