Wave interaction with a submerged floating tunnel in the presence of a bottom mounted submerged porous breakwater

摘要

A coupled model of wave interaction with a submerged floating sea-tunnel in the presence of a bottom mounted submerged porous breakwater is proposed to study the role of porous breakwater in mitigating wave effects on tunnel. In this study, three configurations of the porous breakwater namely trapezoidal, circular and wedge shapes are analyzed. The Sollitt and Cross' model is adopted for fluid flow inside the porous medium. For solution, the problem is handled with eigenfunction expansion for uniform seabed whereas it is handled with mild-slope equation as an approximate technique for arbitrary shape of porous breakwater. Solutions from both the methods are matched at the interface boundaries under certain physical conditions. Reflection and transmission coefficients, and wave forces are calculated for wave and structural parameters. This study reveals that trapezoidal breakwater shows less transmission of waves by dissipating much wave energy and thereby wave forces are mitigated substantially on the tunnel. Parameters are investigated for optimum wave reflection, transmission and wave forces. When the gap between free-surface and tunnel becomes zero, considerable phase shift is found in reflection and transmission coefficients of wave. The present study may be useful for understanding the performance of a porous submerged breakwater having different configurations to protect sea-tunnel from wave action.