Report No. : GEO Report No. 178

Report Title : Report on the Shum Wan Road Landslide of 13 August 1995 (2006), 177 p. (Bilingual)

Author : Sir John Knill & Geotechnical Engineering Office

Abstract

This Report is presented in two volumes. Volume 1 contains the independent findings of Sir John Knill on the Shum Wan Road landslide of August 1995 and the lessons to be learnt from it. Volume 2, prepared by the Geotechnical Engineering Office of the Civil Engineering Department, presents the detailed findings of the landslide investigation. The contents of Volume 2 have been reviewed and agreed by Sir John Knill who relies on them in his own assessment given in Volume 1.

On 13 August 1995, a landslide took place at the hillside above Shum Wan Road, Aberdeen. It caused the collapse of a 30 m long section of Nam Long Shan Road that included a passing bay supported by a fill embankment. The landslide debris crossed Shum Wan Road and damaged three shipyards and a factory near the seafront. The landslide resulted in two fatalities, and five other people were injured.

A comprehensive investigation into the landslide was carried out by the Geotechnical Engineering Office (GEO) during the period August 1995 to March 1996.This detailed study included a desk study, interviews with witnesses, topographic survey, observations and measurements at the landslide site, geological mapping, ground investigation, examination of the condition of drainage systems and water-carrying services, theoretical stability and seepage analyses, and diagnosis of the causes of the failure.

The investigation concluded that the main landslide involved two distinct parts that occurred almost simultaneously. The failure was caused principally by:

1. the presence of weak layers in the ground, i.e. clay seams and clay-infilled joints,
2. ingress of water during prolonged heavy rainfall,
3. a minor failure of the fill embankment below a passing bay on Nam Long Shan Road, and
4. water flowing along Nam Long Shan Road, because of partial blockage of its drainage system, and discharge of part of this water onto the hillside.

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