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The use of quantitative landslide risk assessment (QLRA) in the slope safety system is relatively new in Hong Kong. This paper presents two pioneer cases where QLRA was employed to determine landslide mitigation measures for cost-effective geotechnical risk management. In the first case, the landslide risks posed by the abandoned quarry faces and the natural terrain adjoining a squatter village in Lei Yue Mun were quantitatively assessed. The aim was to draw up a zone where the risk is unacceptable and to confirm the area for squatter clearance. In the second case, the landslide risks, mainly due to debris flow and debris slide hazards, posed by the 194m high natural slope adjacent to a housing development in Fanling Area 49A were assessed using QLRA techniques. The results confirmed the need of landslide and boulder fall barriers to meet the risk acceptance criteria. The paper will describe the main factors considered in the two cases, the acceptable individual and societal risk levels, the methodology for QLRA, the engineering judgement exercised and the role of the Government regulator. |
