An unsteady RANS-based CFD model (STAR-CCM+) is used to optimize the non-reflective chamber and define design loads under the action of extreme focused wave groups for the new sheet-pile quay-wall of Vlora's harbour. The use of different extreme focused wave groups generated according three different spectral wave conditions, i.e. northern exercise condition, southern exercise and extreme conditions, is presented. The proposed method, through spectral analysis of the incident and reflected wave signal, allows the estimation of the reflection coefficients, hence the identification of the best site specific solution. The recorded pressure time series on the structure surfaces, after a validation by comparison with empirical formulas, allows the definition of the design loads.
The development of global trade and ship transportation often requires that the existing docks must be upgraded, consolidated or enlarged, in order to face effectively the increasing demand of people and freight traffic. With such aims, quays over piles with absorbing rubble mound slopes can be used to enlarge or rebuild structures in the existing docks. Generally the rubble mound assures low reflection in the port basins, very important for mooring and manoeuvring but they lead to the construction of very wide superstructures that are not always possible due to the available spaces and economic sources. The use of vertical walls as berthing structures is an alternative quite used in port areas: in fact this kind of solution represents a compromise between the simplicity of construction and the small covered area. Nevertheless vertical quay walls present the drawback of undesirable high wave reflection into the port areas. Low reflecting quays sort out the reflection in port areas by means of porous or open structures that dissipate a part of the incident wave energy. Thereby several different vertical dissipative solutions have been proposed during the last decades as result of research studies from all over the world. To attenuate wave reflection various structures have been designed, being Jarlan-type structures (JarIan, 1961) the most widely used. A JarIan-type structure consists of a perforated chamber which dissipates, basically, the wave energy by turbulence, friction and phase delay between the wave reflection on the front wall and the impermeable back wall. Jarlan-type structure experiments have been widely reported in the literature for short waves (wave period less than 25 s), their results revealing a maximum antireflective efficiency for structures with an antireflective zone width, almost a quarter of the wavelength, being even more effective with a multi-chamber design. However, all the existing antireflective solutions for vertical maritime structures have the drawback of their exiguous efficacy to reduce the reflection of low frequency waves (i.e. wave periods larger than 25 s). To overcome this technical problem, the design of a vertical structure can be based on a multi-cell circuit concept which is considered to be especially effective to reduce the wave reflection of wind waves and oscillations associated with intense storms, resonance waves in port basins, (Medina et al., 2010, Garrido et al 2014). Altomare and Gironella (2014), Matteotti (1991) and Faraci et al. (2012) investigated, by means of physical model tests a quay walls consisting in prefabricated caissons with frontal openings and internal rubble mounds. In cases where the sheet piling is allowed, when great retaining heights have to be achieved a combined quay wall structure is normally used. In this work we investigated, by means of CFD simulations CD-ADAPCO (2013), a structure consisting of a sheet-pile quay-wall, a relieving platform, an anchors and piles foundation system and an antireflective wave chamber filled with a rock armoured slope, Fig.1. The main aim of the paper is to present this new approach for investigating innovative non-reflective quay-wall. Through the paper the optimization of non reflective quay-wall as well as its design phase, based on the numerical results are presented and discussed.
