Development and applications of debris mobility models in Hong Kong

Landslides are major natural hazards that can pose significant risks to human lives and properties in mountainous areas. Mobility assessments of landslide debris are integral to the management of landslide risks. Over the past two decades, the Geotechnical Engineering Office (GEO) in Hong Kong has expended considerable effort on the development of debris mobility models, and a suite of advanced numerical tools has been developed using different numerical techniques, including particle-in-cell, smoothed particle hydrodynamics and arbitrary Lagrangian–Eulerian methods. The accuracy of the tools was corroborated against historical landslides in Hong Kong and typical values of model parameters were established for use in routine practice. These numerical tools offer geotechnical practitioners a pragmatic and efficient approach to assess the dynamics of landslide debris in landslide hazard investigations and quantitative risk assessments. Some of the numerical tools recently developed by the GEO can also be used to assess the dynamic interaction between landslide debris and structural countermeasures, thereby allowing design optimisation. This paper presents a holistic review of the technical development and engineering applications of these numerical tools with a focus on their roles in landslide risk management in Hong Kong. It also documents the experience of Hong Kong in steering and promoting the use of numerical modelling of large ground mass deformations for the purposes of slope safety management.