Critical failure Surface Location using Simple Genetic Algorithm and Multiple Wedge Slope Stability

Established slope stability analysis methods cope well with moderately noncircular shear surfaces, and the Simple Genetic Algorithm (SGA) has been used successfully to find the critical slip surface. In complex situations, for example with concentrated soil reinforcement, strong or weak layers, or concentrated applied loading, the assumptions made to allow ‘rigorous’ analysis are likely to be simplistic. The results of individual analyses could be in error, and the location of the critical slip surface is thus likely to be wrong. The factor of safety could be overestimated because of the impossibility of full shear strength being mobilised all along a shear surface at once, or underestimated because the need to distort the sliding mass of soil as movement takes place is not properly accounted for. In such cases, an engineering judgment has been necessary to identify the potential problem (if it has been recognised at all), and hence an automated optimisation routine cannot work. The multiple wedge method as used here avoids these problems, and so can be used successfully with SGA to identify the critical surface. This is demonstrated here.