Report No. : GEO Report No. 220

Report Title : Review of Landslides in 2005 (2008), 53 p.

Author : S.M. Tam, T.M.F. Lau, A.F.H. Ng & H.S.W. Kong

Abstract

This report presents the findings of a diagnostic review of the landslides in 2005 that were reported to the Geotechnical Engineering Office (GEO) of the Civil Engineering and Development Department. The review forms part of the GEO's systematic landslide investigation programme, which was introduced following the 23 July 1994 Kwun Lung Lau fatal landslide. The aims of this report are to review the performance of the Government's slope safety system and identify areas for improvement in order to further enhance the slope engineering practice in Hong Kong.

Altogether 481 genuine landslides were reported to the Government in 2005. All the available landslide data were examined and 18 landslide incidents were selected for follow-up studies under the systematic landslide investigation programme. These studies provided information and insight into the types and mechanisms of slope failures, and facilitated the identification of areas deserving attention and improvement.

Based on the landslide data in 2005, four major landslides (viz. failure volume of 50 m³ or more) occurred on engineered man-made slopes that have been accepted under the slope safety system. The corresponding annual failure rate is about 0.02% on a slope number basis (i.e. number of landslides relative to the total number of slopes of such category). In terms of minor landslides (viz. failure volume of less than 50 m³) on engineered man-made slopes, the annual failure rate is about 0.11% on a slope number basis.

Overall, about 99.87% of the engineered man-made slopes performed satisfactorily without occurrence of landslides in 2005.

Recommendations for further improvement of the slope safety system and the slope engineering practice in Hong Kong are given in this report.

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