THE EFFECT OF TWIT WEIGHTS OF ROCK AND FLUID ON THE STABILITY OF RUBBLE MOUND BREAKWATERS

Anton Brandtzaeg

Abstract


To study the effect of the specific weights of armour block material and fluid on the stability of rubble mound breakwaters a total of 110 model tests were made, with varying specific weights of armour and fluid, sizes of blocks and slopes of the breakwater face. The tests indicate that in cases where the specific weights deviate much from usual values, the current design formula (Eq. (1)) should be modified by entering a variable quantity, <p , instead of the figure "1" in the denominator. Within the scope of these tests, values varying from <p « 0,37 to <p = 1,05 were indicated. Theoretical considerations seem to show that also higher values of <p may be expected, in particular on account of the effect of the sloping water surface on the buoyancy of the armour blocks. As neither tests nor analysis have given conclusive evidence as to under what conditions higher respectively lower values of <p should be applied, at present only model tests can give the answer in any particular case.

Keywords


unit weights of rock and fluid; breakwater stability; rubble mound breakwater

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