Report No. : GEO Report No. 127

Report Title : Review of 1999 Landslides (2002), 70 p.

Author : K.K.S. Ho, H.W. Chan & T.M. Lam

Abstract

This report aimed to review the performance of Government's slope safety system and identify improvement to current slope engineering practice. It was carried out by the Geotechnical Engineering Office of the Civil Engineering Department, as part of the landslide investigation initiative introduced following the 23 July 1994 Kwun Lung Lau landslide.

About 400 genuine landslides occurred in 1999, all of which had been reviewed. A total of 27 landslide incidents were selected for follow-up study by the 1999 landslide investigation consultant, Fugro Maunsell Scott Wilson Joint Venture. These studies provided information and insight on the types and mechanisms of landslides in Hong Kong and enabled diagnosis of areas requiring attention.

Based on the landslide data in 1999, the annual failure rate in terms of sizeable landslides (i.e. failure volume of 50 m³ or above) on catalogued slopes processed by the slope safety system as being up to the required geotechnical standards is about 0.03%. These include slopes that were previously assessed, designed or upgraded to meet the required geotechnical standards. For slopes dealt with under the Landslip Preventive Measures (LPM) Programme, the annual failure rate in terms of sizeable landslides is about 0.04%.

More than 99.9% of the slopes processed by the slope safety system as being up to the required geotechnical standards performed satisfactorily without the occurrence of any sizeable landslides in 1999.

Recommendations for enhancement of current slope engineering practice are given in this report.

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