Overflow for the Complete Failure of the Downstream Shell of a Rockfill Dam

Resumen

his paper presents the results of experimental research using physical models regarding the failure of the downstream shoulder of rockfill dams caused by overtopping. The aim of this investigation is to analyze how different parameters such as the rockfill permeability, the main geometric dimensions of the dam, or the impervious element type affect the flow that initiates failure and also the ultimate flow needed to break the downstream shell of the dam. The primary objective of this study is to develop predictive models for both discharge flows. For this purpose, tests with stepwise flow increments were performed by varying the rockfill size, the height and width of the dam, the downstream slope and the type of impervious element. The regression analysis was based on results from 61 experimental tests: 50 tests were used to calibrate the formulas and 11 were used for validation. The analysis shows that, for a given dam height, the failure and the initiation discharges depend essentially on the rockfill permeability and, to a lesser extent, on the slope of the downstream shell. The type of impervious element, central core, upstream face or the absence of this element, seems to have no significant effect.