Debris mobility modeling is important and challenging in Hong Kong. Under the concept of equivalent fluid, which is aimed to reproduce the motion experienced by the debris by appropriately choosing the rheology and its parameters, various models have been developed for debris mobility modeling. Yet the appropriateness of the rheologies chosen and the model uncertainties associated with these methods were seldom systematically assessed. In this thesis, recent practice of debris mobility prediction and its limitations will first be reviewed. Then, a methodology is presented to evaluate the relative validity of the rheological choices, in due consideration of model uncertainty and parameter uncertainties using observed past instabilities. The strengths and characteristics of the framework...[ Read more ]

Debris mobility modeling is important and challenging in Hong Kong. Under the concept of equivalent fluid, which is aimed to reproduce the motion experienced by the debris by appropriately choosing the rheology and its parameters, various models have been developed for debris mobility modeling. Yet the appropriateness of the rheologies chosen and the model uncertainties associated with these methods were seldom systematically assessed. In this thesis, recent practice of debris mobility prediction and its limitations will first be reviewed. Then, a methodology is presented to evaluate the relative validity of the rheological choices, in due consideration of model uncertainty and parameter uncertainties using observed past instabilities. The strengths and characteristics of the framework is illustrated using 18 field mapping of apparently high mobility landslides. It is found that the proposed framework could deal with landslides that impinged obstacles satisfactorily. Finally, a site-specific application of the method is conducted for North Lantau Expressway. It is found that the number of past instabilities required to obtain a reasonable estimation on model uncertainty is much less compared to the conventional approach. Meanwhile, the accurate determination of rheology and the model uncertainty of equivalent fluid model plays an important role in hazard prediction. Difficulties, and limitations of the present research as well as future research will also be discussed.