68th Canadian Geotechnical Conference and 7th Canadian Permafrost Conference

POISSON’S RATIO EFFECT OF SLOPE STABILITY CALCULATIONS

Session: Landslides and Slope Stability I / Mouvements de terrain et stabilité des pentes I

Murray Fredlund, SoilVision Systems Ltd. (Canada)
Rob Thode, SoilVision Systems Ltd. (Canada)

This paper presents the results of a study on the effect of varying Poisson’s ratios on limit equilibrium slope stability analyses performed using the dynamic programming search technique. An example model is completed to show the impact of Poisson’s ratio on the strain vectors, the critical slip surfaces and factor of safety. The results showed that decreasing Poisson’s ratio causes the location of the critical slip surface, selected by the dynamic programming method, to move deeper into the slope, leading to a higher factor of safety. The critical slip surface is selected based upon kinematic admissibility criteria. The results of the method were also shown to become numerically unstable as cohesion approaches zero if adjustments to the kinematic admissibility criteria are not made. Therefore, care needs to be taken when analyzing cohesionless soils with low values of Poisson’s ratio.