Numerical model for clay core dam breach process due to overtopping considering different failure modes of core wall

Based on the breach mechanism of clay core dam due to overtopping failure, a numerical model for dam breaching process is put forward. In this model, the initial scour position on the downstream slope is determined by means of the characteristics of dam figuration and overtopping flow, the broad-crested weir formula is adopted to calculate breach flow discharge, and a time averaged backward erosion formula is adopted to simulate the dam shell breach. The moment and mechanical equilibrium methods are utilized to model the overturning and sliding failures of the core, respectively. In order to simulate the actual failure mode of the dam, one-and two-sided erosion, as well as dam base erosion, are taken into account. The model adopts the iterative calculation method to simulate the coupling process of water and soil during dam breaching. 10 clay core dam overtopping failure cases which have measured data are adopted to testify the present model. The comparison of measured data and calculated results on peak breach flow, final breach width and failure time shows that the calculated results can meet the engineering requirements, and the statistics of model’s relative errors validate the reasonability of the present model.