Geological characterisation of the Lai Ping Road Landslide

This report describes the geological and engineering geological features of the Lai Ping Road Landslide which occurred on the evening of the 2nd of July 1997 during an exceptionally heavy rain storm. There were no injuries or major damage to property. The landslide affected a cut slope and adjoining quasi-natural terrain up-slope. The cut slope has had a long history of failure, and although the subject of earlier phases of gound investigation, no remedial work was carried out. The report was produced by the Planning Division as part of a wider technical investigation by GEO (Sun and Campbell, 1998), and in parallel with consultants working on behalf of the Territory Development Department. The landslide comprises a series of failures at five locations within the original cut slope. All but one of these represent the reactivation of an existing failure scar. Extensive deformation was also identified in the quasi-natural terrain above the cut slope indicating a larger composite (Cruden and Varnes, 1997) landsilde. Subsequent ground investigation has demonstrated that the composite landslide affects a thick saprolite mass (c. 20 m) and has an estimated volume in the order of 100,000 m3. The report summarises the results of aerial photograph interpretation, a desk study, detailed geological and engineering geological mapping, and a comprehensive ground investigation.