本研究以理論解析探討波浪與前後相連複合式透水彈性潛堤互相作用之問題，本文延伸Lan and Lee(2010)提出之單一透水彈性潛堤進行理論解析。兩種複合潛堤之材料皆為均質且等向透水之彈性介質。本文在求解上，將問題的領域區分為五個部分，藉由交界面邊界條件的連續性，即潛堤前後材質的相連交界面、潛堤與流體交界面處之動力邊界條件壓力連續與質量通率連續，配合正交特性將波浪與複合式透水彈性潛堤互制問題聯立求解，據以求得波浪與複合式透水彈性潛堤之解。
在模式驗證上，本文將理論解析退化為單一材質之潛堤與Mei and Black(1969)之不透水剛性潛堤，李和劉(1995)與藍(2000)之透水剛性潛堤，以及Lan and Lee(2010)之透水彈性潛堤的理論解析結果比較，均得到良好的一致性。本文先藉由定性分析，觀察由柔性材質與剛硬性材質前後組成之複合式透水彈性結構物，受波浪作用後的運動特性。文中再選取兩種幾何形狀的複合式透水彈性潛堤，分別探討影響參數如前後堤寬改變、滲透係數變化及剪力模數對波浪的影響。
根據分析結果顯示，在潛堤堤寬較大(b/d≧2.0)的情況下，其材質為一硬一軟組合時，當材質較硬的部分其剪力模數在G≧5×10^5 N/m^2的範圍，G值變化對波浪反射率、透過率與能量損失的改變不大；而在潛堤堤寬較小(b/d≦0.3)的情況下，其材質剪力模數為G=1×10^4 N/m^2(柔性)與G=1×10^8 N/m^2(剛性)之組合時，結構物的彈性效應對波浪影響很小，但是當剪力模數組合變為G=1×10^4 N/m^2(柔性)與G=5×10^5 N/m^2(硬質柔性)時，在柔性材質寬度最大(硬質柔性材質寬度最小)的條件下，結構物的彈性效應影響波浪的情形仍相當明顯。

Wave propagation over a combined submerged poro-elastic structure with different materials is investigated theoretically. Lan and Lee’s (2010) theory was extended to derive a new analytical solution for describing the interaction between waves and a combined poro-elastic submerged structure. Lineary wave theory is used to analyze wave motion based an extending Biot’s theory including the turbulent frictional effect. In the present approach, the problem is divided into five domains in which matching boundary conditions as well as dynamic and kinematic conditions are employed in each connection region. Mass conservation of the poro-elastic structure and the equation of state for pore fluid are also used to arrive at the wave fields and displacement of the poro-elastic structure.
The present analytical solutions are identical to Lee and Liu (1995), Lan (2000), and Lan and Lee’s (2001) analytical results for the cases of a single breakwater with impermeable rigid, porous, and poro-elastic structures. Kinematic characteristics for the combined elastic and rigid porous structures on waves are studied. The effects of influence parameters for different geometries of poro-elastic structures with various width, intrinsic permeability and shear modulus.
From the present study the following major results can be addressed: (1) For a wider composite submerged poro-elastic structure with different shear modulus (b/d≧2.0), when the shear modulus of the harder material is in the region of G≧5×10^5 N/m^2, changes of shear modulus effect on wave reflection, transmission and energy dissipation are not remarkable. (2) For a narrower submerged poro-elastic structure with soft and rigid combination (b/d≦0.3), the effect of elasticity on waves is less obvious. However, different results are obtained for the composite breakwater with soft and quasirigid combination. In the case of larger width of soft material, the elastic deformation apparently affects the variation of wave field.

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