Hydraulic performance of double perforated seawalls

Many coastal structures constructed for the purpose of harbour securing and shore protectionare porous. For many years, rubble-mound type porous structures are extensively used.However, vertical permeable structures are seldom used due to limited information on thehydraulic performances.The seawall structures which have vertical faced walls are exposed to wave actions such asrunup, overtopping or reflection. After these actions, waves cause various hazards bothforward and back of structure and upon of structure. These situations cause navigationproblems for vessels and worsens mooring conditions, cargo/passenger movements in theharbour basins. Furthermore, other hazards affect drivers and passengers in road vehicles ortrains back to shore protection facilities. There are some alternatives of perforated seawalls toreduce of reflection and overtopping on vertical seawalls.This study is an investigation of hydraulic performance of double perforated walls withregular and nonbreaking wave conditions and different wave characteristics. The hydraulicperformance of walls consider such as wall permeability, attribute of reflection andovertopping. Wave overtopping is neglected in this study, but walls have satisfying height forevaluating on reflection and transmission.Consequently, the reflection and transmission cofficients came out with evaluating reflectionand transmission wave height of double waves. Thus, the performances of double seawallswhich have different porosity are appreciated under different locations and wave conditions.Tests have revealed that the most effective parameters for the reflection and transmissionperformance of the double perforated vertical walls are the relative wave height, (Hi/d), thestructure porosity, (P) and relative screen spacing, (B/Li).Key words: Double perforated vertical walls, hydraulic performance, wave reflection, wavetransmission.