Report No. : GEO Report No. 104

Report Title : Review of Natural Terrain Landslide Debris-resisting Barrier Design (2000), 91 p.

Author : D.O.K. Lo

Abstract

The demand for land in the hilly terrain of Hong Kong means there is increasing pressure for developments to encroach onto the steeper parts of its natural terrain. Typically more than 300 natural terrain landslides occur in Hong Kong every year. The vast majority of these are shallow failures involving the top few metres of the ground surface and some may develop into channelised debris flows with long runout. Given the close proximity of some of the developments to natural hillsides, even a relatively small failure can potentially result in serious consequences.

Preventive works on the hillside can be extensive and prohibitively costly and landslide barriers may prove to be a cost-effective solution in certain situations. This study examines some salient aspects of the design of barriers for natural terrain landslides. Key data on some of the barriers constructed in Hong Kong are presented. Various approaches put forward in the literature for evaluating the impact loads on barriers have been reviewed and this illustrates, inter alia, the considerable scatter in the predictions as well as in some of the reported field measurements.

Based on the present state of knowledge, some suggestions are put forward to facilitate the assessment of debris mobility and debris impact loads in the design of landslide debris-resisting barriers. Given the developments in the subject, the suggestions are intended to be interim. They will be reviewed and updated when new data and results of further research become available.

Further research is needed to gain a better fundamental understanding of the nature and mechanisms of natural hillside failures in Hong Kong and to improve the methods for assessment of debris mobility and debris impact loads under local conditions.

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