This standard provides criteria and guidelines for the hydraulic design of rubble mound breakwaters. It focuses on determining armour unit stability against wave action using the Hudson formula, and provides recommendations for the geometric design of the breakwater's cross-section, including crest, slopes, and filter layers.
Specifies criteria for the design of rubble mound breakwaters, including design waves, stability, and material requirements.
Quick Reference Values
Specific weight of sea water (γw)1.025 t/m³
Typical Stability Coefficient (Kd) for rough angular quarry stone (2 layers, trunk)2.0
Typical armour layer slope (cot α)1.5 to 2.0
Specific weight of rock (γr)2.65 t/m³
Porosity of armour layer37-40 %
Key Formulas
W = (γr * H³) / (Kd * (Sr - 1)³ * cot α) — Hudson's formula for Armour Unit Weight (W=weight, γr=unit wt of rock, H=wave height, Kd=stability coeff, Sr=specific gravity of rock, α=slope angle)
Practical Notes
This standard is outdated and has been superseded by IS 16474. It should be used for reference purposes only.
The core of this code is the Hudson formula, which is known to be less accurate for breaking waves or steep slopes. Modern designs often use the Van der Meer formulas or physical model testing for optimization and verification.
The selection of the Stability Coefficient (Kd) from Table 1 is the most critical and sensitive parameter in the design. It requires significant engineering judgment based on armour shape, placement method, and wave conditions.