For concrete breakwater elements often a variant of the Hudson formula is used. Therefore nowadays for armourstone the Van der Meer formula or a variant of it is used. It is not possible to estimate the degree of damage on a breakwater during a storm with this formula. (2004) formulations is proposed and tested by physical model experiments. Based on the results of this study, a new design flowchart that uses Van der Meer (1988) and Van Gent et al. Also it is not valid for breakwaters and shore protections with an impermeable core. The use of rock in hydraulic engineering (2007) are discussed. The drawback of the Hudson formula is that it is only valid for relatively steep waves (so for waves during storms, and less for swell waves). This formula has been for many years the US standard for the design of rock structures under influence of wave action Obviously, these equations may be used for preliminary design, but scale model testing (2D in wave flume, and 3D in wave basin) is absolutely needed before construction is undertaken. Authors: van der Meer, J W Publication Date: 1986-12 Media Info. Availability: Find a library where document is available. The formulas have been rewritten in the form of reliability functions and can be used for probabilistic design. The armourstone may be considered stable if the stability number N s = H s / Δ D n50 3. A deterministic approach was used in drawing design graphs. θ is the angle of revetment with the horizontal.K D = around 10 for artificial interlocking concrete blocks.K D is a dimensionless stability coefficient, deduced from laboratory experiments for different kinds of armor blocks and for very small damage (a few blocks removed from the armor layer) (-):.D n50 is the nominal median diameter of armor blocks = (W 50/ρ r) 1/3 (m).ρ r and ρ w are the densities of rock and (sea)water (kg/m 3).(ρ r / ρ w - 1) = around 1.58 for granite in sea water very shallow water, physical model tests, Van Der Meer’s formula INTRODUCTION Project. Δ is the dimensionless relative buoyant density of rock, i.e. Rubble Mound Breakwater Design Example Given: Design Conditions Water depth: 5.5 m Beach slope: 1:20 Design high water: 1.7 m Design wave Hs 2 m.H s is the design significant wave height at the toe of the structure (m).The equation was developed by the United States Army Corps of Engineers, Waterways Experiment Station (WES), following extensive investigations by Hudson (1953, 1959, 1961a, 1961b) Initial equation (2004) formulas are applied as recommended by The Rock Manual: The. Hudson's equation, also known as Hudson formula, is an equation used by coastal engineers to calculate the minimum size of riprap ( armourstone) required to provide satisfactory stability characteristics for rubble structures such as breakwaters under attack from storm wave conditions. An example study showed that there may be 70 difference in armour stone weight when Van der Meer (1988) and Van Gent et al.
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