Bearing capacity analysis of submerged slopes subjected to water drawdown based on a nonassociated flow rule and nonlinear failure criteria

Water level drawdowns that occur outside and inside a fully, or partially, submerged slope will change the hydraulic gradient and enhance seepage forces, and may thus lead to slope instability and collapse. Existing research on this stability issue has primarily focused on the use of linear failure criteria and the associated flow rule. Little attention has been given to the effects of nonlinearity and the nonassociated plasticity of geomaterials, and of surcharge loading on slope stability. However, these conditions are more realistic for real-world cases. This study addresses this knowledge gap. The limiting surcharge on the top of submerged slopes subjected to water drawdown is analyzed in terms of nonlinearity and dilation effects using a limit analysis method. The optimal solutions were sought through optimization. The proposed method and its assumed failure mechanism were validated by comparing the results of the proposed method with results from finite element and finite element limit analysis. Parametric analysis and a case study are presented and indicate that as the water level difference increases, the bearing capacity of the slope decreases. In addition, it was found that the dilatancy effect has an effect on slope bearing capacity and that the inclusion of nonlinear effects enables better results.