Rayleigh波作用下饱和海床土中管桩竖向动力特性研究

Vertical dynamic responses of pipe piles in saturated seabed soil subjected to Rayleigh wave action

针对近海环境中钢管桩在Rayleigh波作用下的竖向动力特性进行了研究。基于Biot理论和理想流体控制方程,结合上覆流体与海床面的位移,应力以及动水压力连续性条件,求得了流体-饱和介质在Rayleigh波作用下的自由场波动解;接着考虑大直径管桩的横向惯性效应,借助管桩内外侧土体竖向动力阻抗,建立了Rayleigh波作用下饱和海床土中管桩竖向动力响应的频域解答。结果表明:海床及管桩竖向位移随着流体层厚度的增加逐渐降低,当流体层厚度超过10 m时,则基本保持不变;桩径的增大将使不同桩顶质量下的管桩竖向位移逐渐减小,并最终趋于同一数值;桩侧摩阻力在海床面以下2.5倍波长范围内随土体剪切模量的增大而减小,当深度进一步增大时,则基本一致。

The vertical dynamic responses of steel pipe piles under the action of Rayleigh wave in offshore environment were studied.Based on the Biot theory and ideal fluid control equation,in consideration of the displacement,stress and hydrodynamic pressure continuity conditions of overlying fluid and seabed surface,the free field wave solution of fluid-saturated medium under the action of Rayleigh wave was obtained.Considering the lateral inertia effect of large-diameter pipe piles,the frequency domain solution of vertical dynamic responses of pipe piles in bed soil under the action of Rayleigh wave was presented with the help of the vertical dynamic impedance of soil inside and outside the pipe piles.The results show that the vertical displacement of the seabed and the piles decreases with the increase of thickness of the fluid layer.When the thickness of the fluid layer exceeds 10 m,the vertical displacement of the piles remains unchanged.The increase of the pile diameter will gradually reduce the vertical displacement of the piles with different pile top mass,and it will eventually tend to the same value.The side friction of the pile decreases with the increase of the shear modulus of the soil under the seabed surface within a depth of 2.5 times wavelength.When the depth is further increased,it is basically the same.