Parameters Affecting Stability of Rubble Mounds

The paper examines the hydraulic reasons for failure of rubble structures suggesting improvements in design methods. The importance of forces by uprush and downrush, and forces depending upon friction and permeability is analyzed. The most dangerous combinations of these forces and of resonance between uprush/downrush period and wave period is evaluated. The conclusion is that armor units should be placed. Impermeable sheets should be put in the upper as well as in the lower part of the slope. Furthermore the commonly used trapezoidal linear slope profile should be substituted by better reasoned design to obtain a greater degree of compatability between the wave action, slope geometry structure, and armor unit geometry. A self-adjusted profile may be divided into three zones with different slope angle and block-characteristics and combined to achieve maximum stability.