Three-dimensional stability analysis of slopes using a plastic limit method

This paper presents a three-dimensional (3-D) numerical upper bound method for slope stability analysis. The 3-D method is an extension of the two-dimensional (2-D) upper bound method developed by Donald & Chen (1997). The failure mass in this 3-D method is divided into a number of prisms with vertical or inclined interfaces. The factor of safety is only involved in the energy-work-balance equation and can be determined using an iterative technique. To illustrate the proposed 3-D method and its practical application, a back-analysis of the landslide occurred at Milestone 14(1/2), Castle Peak Road on 7 August 1994, Hong Kong, is carried out, The main analysis results are presented and discussed in this paper.