Numerical simulation study of seepage field before and after the failure of piping outlet in double-stratum dike foundation

GeoStudio software was used to simulate the distribution of hydraulic gradient before and after the failure of the piping outlet in the double-stratum dike foundation. By comparing the changes in hydraulic gradient and flow velocity in the dike foundation before and after the failure of the piping outlet, the weak position was determined. The results show that the pressure head in the double-stratum dike foundation before the failure of the piping outlet is mainly borne by the overlying clay layer, and it is then borne by the underlying sand and gravel layer after the failure of the piping. The maximum flow velocity is transferred from the foot of the dike to the outlet of the piping.