Slope stability analysis by strength reduction HI8mNX3 "j
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KEYWORDS: embankments; landslides; limit state design analysis; numerical modelling and analysis;plasticity; slopes. }5
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INTRODUCTION !5ps,+o
For slopes, the factor of safety F is traditionally de®ned as the ratio of the actual soil shear strength to the minimum shear strength required to prevent failure (Bishop, 1955). As Duncan (1996) points out, F is the factor by which the soil shear strength must be divided to bring the slope to the verge of failure. Since it is de®ned as a shear strength reduction factor, an obvious way of computing F with a ®nite element or ®nite difference program is simply to reduce the soil shear strength until collapse occurs. The resulting factor of safety is the ratio of the soil's actual shear strength to the reduced shear strength at failure. This `shear strength reduction technique' was used as early as 1975 by Zienkiewicz et al. (1975), and has since been applied by Naylor (1982), Donald & Giam (1988), Matsui & San (1992), Ugai (1989), Ugai & Leshchinsky (1995) and others. z!}E2j_9P
The shear strength reduction technique has a number of advantages over the method of slices for slope stability analysis. Most importantly, the critical failure surface is found automatically. Application of the technique has been limited in the past due to the long computer run times required. But with the increasing speed of desktop computers,the technique is becoming a reasonable alternative to the method of slices, and is being used increasingly in engineering practice. However,there has been little investigation of the accuracyof the technique. In this paper, factors of safety obtained with the shear strength reduction technique are compared to limit analysis solutions for a homogeneous embankment.
