Interaction between along-shore drift flow and marine water-development works

Abstract

A unique approach is developed for determination of along-shore flow rate of drift on beaches.For the majority of marine ports, thick enclosing structures are required to protect the water body of the port from waves and other external effects. Having considerable length in the direction transverse to the shore, the enclosing structures intercept littoral drift flowing along the shore. As a rule, these structures are designed to be impermeable to drift, since drift protection of the water body on which the port is located is one of the problems encountered in their construction.Studies of drift movement in the littoral zone of a sea, and the models and computational methods that have been developed on the basis of this drift [1 -3] have made it possible to solve many problems of the interaction between drift movement and structures. Moeover, problems requiring additional research remain unresolved.Flat beaches comprised primarily of sandy drift with particle diameters ranging from 0.1 to 1.0 mm are characteristic of certain seas of Russia (Baltic, Barents, Okhotsk). Other seas (Black) possess beaches that drop-off sharply and are comprised of sandy-gravelly-pebbly drift with particle diameters of the gravelly-pebbly fractions ranging from 1.0 to 50.0 mm. The sandy beaches, however, may also include slime fractions, and coarse inclusions right up to boulders.In engineering analyses, various relationships are employed to determine the along-shore flow rates of sandy and pebbly drift; historically, this is base on an understanding of various interactions between waves and flat beaches and beaches that drop-off sharply. The majority of relationships for the transport of drift in the littoral zone of a sea include calibration factors obtained from measurements in the section under investigation.Geologic-engineering surveys, and also experimental investigations [4,5] indicate that the material of a beach in its above-water and underwater sections is distributed nonuniformly over the transverse profile. This is caused by nonuniform initial distribution of the beach material, which is then subjected to wave action. Moreover, the maximum average size of the material is observed to be somewhat greater than the upper limit of the roll of the waves [4]. When moving in the direction of sea, the average size of the material decreases along the profile of the beach.This redistribution of material is characteristic of both sandy, and also pebbly beaches, and in certain sections of the littoral zone, it results in the formation of a profile comprised of sand in the lower underwater portion, and pebbles, and then gravel along the above-water profile. Similar transverse beach profiles have been measured for the littoral zone of the Imeretinsk Depression (Sochi), where it is planned to construct freight-handling marine ports -new freight-handling areas for the marine port of Sochi.The flow rates of pebbly and sandy drift are usually accounted for by different relationships, but, here, the actual beaches have sandy and pebbly section...

Mathematical modeling of lithodynamic processes

“…A unified approach to determining sediment rate on pebble and sandy beaches is based on the modification of energy formulas for alongshore sediment rate. At the same time, in addition to the features of beaches, this approach also takes into account the distribution of sediments along its profile [5,6].…”