Dolos Hydraulic-Stability Formula Update and Optimum Packing Density

Abstract

This paper effectively summarizes dolos stability results for a slope of 1:1.5 that were obtained from the same flume at the Council for Scientific and Industrial Research (CSIR) laboratory in Stellenbosch, South Africa, over a period of more than 10 years. The initial CSIR investigation into dolos stability was conducted with regular waves and included the effect of packing density, concrete density, storm duration, and waist-to-height ratio. Subsequent investigations into the effect of wave period, armor slope, and waist-to-height ratio were conducted with irregular waves yielding 316 data points. These data formed the basis of the present dolos stability formulas. For establishing the effect of packing density, 286 regular wave results were used. The analysis included the establishment of a relationship between packing density and ultimate displacement just prior to failure. An optimum packing density can be estimated by using this approach together with the change in displacements as a function of packing density. The effect of concrete density on stability as previously established in the same flume was included in the formulas, as was the effect of storm duration. Final stability formulas were compared with those of other researchers for dolosse, tetrapods, cubes, and Accropode (SOGREAH, Echirolles, France).