| Summary: | 碩士 === 國立中興大學 === 水土保持學系所 === 94 === The hazards of debris flow triggered by earthquake activities and heavy rainfalls occur frequently in Taiwan along the past decades. Especially after the 921 earthquake in 1999, considerable damages of debris flow hazards in hillside resident areas are increasing dramatically in which debris flow become a major obstacle for engineers to deal with. Accordingly, the study on the mitigation of debris flow hazards is the major concern in Taiwan.
Based on the observation from colluviums of conglomerate formation in certral and east Taiwan, it is found that the granular debris flow is the major type in these areas. The Discontinuous Deformation Analysis (DDA) is therefore adopted to study the initiation and mechanism of the granular debris flow. To properly model the behaviour of the granular debris flow, several modifications including the consideration of water effects, linear distributed line load, and drag forces have been made.
The methodology proposed in this study has been examined through the calculation of a number of numerical examples and comparison with available analytical results. Application examples were also provided to demonstrate the applicability of the revised DDA method. In addition, the influence of several important factors such as slope, friction angle, and water depth (or flow discharge) on the initiation of the granular debris flow were studied. The results obtained show that: (1) the DDA method can be a useful tool to model the initiation and mechanism of the granular debris flow under different situations, and (2) the hydrodynamic mechanism of mixed fluid and solid particles needs to be further studied.
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