Stability Of Armour Layer Research Articles

Discussion of “ Armor Layer Stability of Rubble‐Mound Breakwaters ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Discussion of “ <i>Armor Layer Stability of Rubble‐Mound Breakwaters</i> ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Discussion of “ Armor Layer Stability of Rubble‐Mound Breakwaters ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Discussion of “ <i>Armor Layer Stability of Rubble‐Mound Breakwaters</i> ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Discussion of “ Armor Layer Stability of Rubble‐Mound Breakwaters ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Discussion of “ <i>Armor Layer Stability of Rubble‐Mound Breakwaters</i> ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Discussion of “ Armor Layer Stability of Rubble‐Mound Breakwaters ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Discussion of “ <i>Armor Layer Stability of Rubble‐Mound Breakwaters</i> ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Discussion of “ Armor Layer Stability of Rubble‐Mound Breakwaters ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Discussion of “ <i>Armor Layer Stability of Rubble‐Mound Breakwaters</i> ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Closure to “ Armor Layer Stability of Rubble‐Mound Breakwaters ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Closure to “ <i>Armor Layer Stability of Rubble‐Mound Breakwaters</i> ” by Per Anders Hedar (May, 1986, Vol. 112, No. 3)

Pilot study of an aggregate abrasion test for breakwater armourstone

The long-term performance of the materials out of which breakwaters and coastal protection works are constructed depends not only on physico-chemical degradation processes but also on the mechanical abrasion resistance of the rock or concrete used. The abrasion of breakwater armourstone affects the armour layer stability directly by causing weight loss from the rock blocks. Another important though unquantified source of stability reduction in the armour layer is the progressive rounding of armour by abrasion leading to poor interlocking between individual blocks and their neighbours (see the discussion of this phenomenon by Dibb et al. 1983). Gupta (1985) and others have demonstrated that there is a relative decrease in aggregate (macro)porosity for rounded compared with angular fragments. Such a decrease in an armour layer porosity due to the rounding of blocks may have a deleterious effect on energy absorbing properties of the layer. The assessment of abrasion resistance is therefore of great interest to the engineer concerned with in-service deterioration of armour layer performance. New quantitative methods for measuring the effects of abrasion on the entire profile of the breakwater armour layer were reported by Latham &amp; Poole (1986). Several standard engineering tests and analytical procedures have been recommended for the assessment of suitability of a particular rock for breakwater core and armour material (Fookes &amp; Poole 1981; Allsop et al. 1985). The test values recommended for acceptance by Allsop et al. are drawn from a list of tests which does not include an abrasion resistance test, although several abrasion

Stability of breakwater armour layers — design formulae

New practical design formulae have been developed which describe the stability of rubble mound revetments and breakwaters under random wave attack. The formulae are based upon a series of model tests. More than two hundred and fifty tests have been performed in order to ensure that all the relevant variables could be varied systematically. As a result of the present series of investigations the main shortcomings in Hudson-type formulae have been solved. Stability formulae are given which include the influence of wave period, number of waves, armour grading, spectrum shape, groupiness of waves and the permeability of the core. A clearly defined damage level parameter is introduced in the formulae.

Armor Layer Stability of Rubble‐Mound Breakwaters

Improved stability formulas for rubble‐mound breakwaters are developed. These formulas for the design of the required weight of the armor units in the cover layer reflect the complex phenomena and take into account the most important parameters affecting the stability. The influence of the wave climate, the difference between the angle of repose and the slope angle, the density of the block material and the fluid, and the permeability of the underlayers are involved. The weight of the armor units under no‐damage conditions is in this way determined. The method may be a contribution to a better understanding and explanation of why some rock‐fill breakwaters have recently failed.

Stability of Armour Layers in Rivers

The importance of both the overpassing and the embedding of river bed particles is demonstrated by experiments. When a single layer thick armouring layer of uniform d\d1 size particles on a bed of uniform finer d\d2 size particles is broken at one location the stability of the remainder of the armour layer depends on the tendency of the d\d1 particles to embed into the surface of d\d2 particles. If a d\d1 size particle is seated in the exposed position on the surface of the d\d2 sized bed sediment it may, by virtue of its exposure to the flow, be preferentially entrained and it may then overpass the finer bed sediment. Alternatively, the d\d1 particle may be too large for overpassing and it will become embedded. Armour layers composed of particles which embed, tend to be more stable.