American Society of Civil Engineers

Paper describing the development of the "Hudson formula" for the stability of armor on a breakwater.

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Laboratory investigation of rubble-mound breakwaters

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Design of Riprap Revetment

This paper examines the applicability of a neural network to analyze model test data of the stability of rubble-mound breakwaters. The neural network is an information-processing system, modeled on the structure of the human brain, that is able to deal with information whose interrelation is not clear. Seven parameters concerning the stability of rock slopes are used: the stability number, the damage level, the number of attacking waves, the surf-similarity parameter, the permeability parameter, the dimensionless water depth in front of the structure, and the spectral shape parameter. The damage levels predicted by the neural network, calibrated by using a part of Van der Meer’s 1988 experimental data, agree satisfactorily well with the measured damage levels of another part of the data source by Van der Meer 1988 and by Smith et al.’s 1992 data. The agreement between the predicted stability numbers by the neural network and the measured stability numbers is also good.

Neural network for stability analysis of rubble-mound breakwaters

Hydraulic scale modelling involves scale effects. The limiting criteria for scale models of subaerial landslide generated impulse waves including solid, air, and water are discussed both based on a literature review and based on detailed two-dimensional experimentation. Seven scale series based on the Froude similitude were conducted involving the intermediate-water wave spectrum. Scale effects were primarily attributed to the impact crater formation, the air entrainment and detrainment, and the turbulent boundary layer as a function of surface tension and fluid viscosity. These effects reduce the relative wave amplitude and the wave attenuation as compared with reference experiments. Wave amplitude attenuation was found to be more than 70 times larger than predicted with the standard wave theory. Limitations for plane impulse wave generation on the basis of the present research are given by which scale effects can be avoided.

/pdf/scale-effects-in-subaerial-landslide-generated-impulse-waves-137qaavyki.pdf

Scale effects in subaerial landslide generated impulse waves

Design of quarry-stone cover layers for rubble-mound breakwaters

This paper reports on a laboratory investigation conducted at the United States Army Engineer Waterways experiment station, Vickburg, Mississippi, to determine criteria for the design and construction of rubble mound breakwaters. Small-scale breakwater sections are hand-constructed in a concrete wave flume 119 ft long, 5ft wide, 4 ft deep, and subjected to mechanically generated waves to determine the stability of the armor units. A general stability equation has been derived and is being used to guide the experimental program and correlate the test data. From the test data obtained important unknown functions in the general stability equation have been determined for selected breakwater and test-wave conditions, and a new breakwater stability formula has been obtained. In conjunction with the stability tests, wave run-up data are obtained for each breakwater section and wave condition tested. Also, measurements are obtained that enable the thickness and porosity of cover layers composed of different types of armor units to be determined. The new stability formula and the experimental data obtained so far have provided essential information for an improved method of designing rubble-mound breakwaters with protective cover layers composed of quarry-stone and tetrapod armor units. Tests in progress (1959) to obtain experimental data for other special shapes of cast concrete armor units (cubes, tetrahedrons, and tribars) should increase considerably the accuracy of rubble-mound breakwater design.

/pdf/laboratory-investigations-of-rubble-mound-breakwaters-50pun0zpax.pdf

Laboratory investigations of rubble-mound breakwaters

Tests to determine stability characteristics of various armor-unit shapes; new stability formula for rubble breakwaters was derived, which provides essential information for improved design; stability, thickness, and porosity data are presented for quarry-stone and tetrapod armor units.

/pdf/laboratory-investigation-of-rubble-mound-breakwaters-1s0hvlx6fp.pdf

Robert Y. Hudson

Papers

Laboratory investigation of rubble-mound breakwaters

Design of quarry-stone cover layers for rubble-mound breakwaters

Laboratory investigations of rubble-mound breakwaters

Laboratory Investigation of Rubble-Mound Breakwaters

Engineering Aspects of Water Waves: A Symposium: Wave Forces on Breakwaters