Investigating the Effect of Geometrical Changes of Earth Dam Dimensional Parameters on the Assessment of Piping Failure Discharge with Considering Uncertainty in the Mechanical Properties of Materials

The aim of this paper is to study the uncertainty in piping failure of the Teton earth Dam with considering geometrical parameters and material uncertainty using the BREACH-GUI model. Piping phenomenon in the body of the dam is one of the two common factors in the dam failure, which is a small intubation in the early hours with low diameter and low flow rate, due to erosion of the tunnel walls, the erosion of the tunnel walls increases the diameter of the tunnel and the flow of water passing through It will be tunnel that, if this amount of flow exceeds a limit, it will break the body of the dam and ultimately lead to the complete destruction of the body of the dam. Predicting the main breach characteristics (size, shape, time of formation) and the break outflow hydrograph with Monte Carlo uncertainty simulation are presented in this paper. The model is physically based on the principles of hydraulics, sediment transport, soil mechanics, geometric and material properties of the dam, and the reservoir properties (storage volume, spillway characteristics, and time- dependent reservoir inflow rate).Obtained results show that, the critical uncertainty parameters that produce the shortest time and maximum discharge flow arising from dam failure are  (frictional angle) and D50 (efficient diameter of soil). Obtained results show that earth dams with smaller shape factor fails faster and also with increasing in the level of water in the reservoir earth dam piping failure of dam intensify and also with increasing height of dam with constant shape factor the possibility of piping failure of dam is increased.