Failure Analysis of Gated Culvert Structure by Numerical Simulations

This paper summarizes the investigation of a failure of a gate-controlled culvert structure made of precast concrete segments while operating under high flow. Seepage underneath the culvert and the complex hydrodynamic conditions induced by the flow in the culvert were studied separately to ascertain their relevance in the structure's failure. Seepage was studied by the Analytic Element Method including estimates of uncertainties in model output by Predictive Analysis techniques. The flow structure in the culvert (velocity and pressure fields) was modeled by Reynolds-Averaged Navier-Stokes (RANS) while pressure fluctuations were modeled using Detached Eddy Simulations (DES). Results suggest that the seals used at the culvert segments failed from the combined effect of pore pressure from seepage flow combined with negative pressure fluctuations within the culvert barrel induced by the flow behind the partly open gate. After seal failure, negative pressures promoted high exit-seepage gradients at the joints that induced piping and erosion of the foundation and ultimately resulted in dislodgement of the culvert segments.