The three trigger methods are: a water surface elevation, a water surface elevation plus a duration of time that the water is above that elevation, and a specific time and date. Trigger Failure At - This field is used to select one of three trigger methods for initiating the breach. This elevation should be entered as the center of the piping flow while the breach develops. If a piping failure mode is selected the user must enter an initial piping elevation. However, for a piping breach, the coefficient should be lower to represent all of the additional energy losses occurring.

Typical Orifice coefficients for a true designed orifice are around 0.8. This coefficient is an Orifice coefficient, which is used while flow is coming out of the dam in a piping mode. Piping Coefficient - If a piping failure mode is selected, the user must enter a piping coefficient. This time represents the duration from when the breach begins to have some significant erosion, to the full development of the breach.įailure Mode - This option allows the user to choose between two different failure modes, an Overtopping failure and a Piping failure. Suggested range of values are 2.0 to 3.2, with 2.6 as a default value for most earth dams.īreach Formation Time (hrs) - This field is used to enter the breach development time in hours. For an overtopping failure, or when the top of a piping failure collapses, the program uses a weir equation to calculate the flow through the breach.

Right Side Slope - This is the right side slope of the trapezoidal breach.īreach Weir Coef – This field is used for entering a weir coefficient for the breach area. Left Side Slope - This is the left side slope of the trapezoidal breach. If the ' User Entered Data' Breaching Method is selected, then the following data must be entered for the breaching analysis:Ĭenter Station - This field is used for entering the centerline stationing of the final breach.įinal Bottom Width - This field is used to enter the bottom width of the breach at its maximum size.įinal Bottom Elevation - This field is used to enter the elevation of the bottom of the breach after it has been fully developed.

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