Reliability analysis of slopes under slow drawdown conditions

In the analysis of slope stability under slow drawdown conditions, it has been shown that there exists a critical pool level that results in the minimum factor of safety. This paper will use the random finite-element method (RFEM) to conduct reliability analyses of slopes subjected to slow drawdown. It is shown that the critical pool level corresponding to the maximum probability of failure is affected by a non-dimensional stability number in relation to shear strengths, unit weight and slope height. For flatter slopes, the critical pool level is also affected by the depth ratio. At the critical pool level, more slope failures will be obtained by RFEM, due to the trade-off between the destabilising influence of internal pore pressures and the stabilising influence of exterior hydrostatic pressures.