海底软弱场地非线性地震反应及其应用研究

Nonlinear seismic ground response analysis and implications for soft site in Bohai seafloor

海底软弱场地土具有较强的非线性特性,频域等效线性模型及方法将不足以反应海底软土动力响应的真实情况,因此为了更合理地估计海底软弱场地对地震动的影响,运用一种考虑拟合阻尼比、刚度比试验曲线的时域分析方法,对渤海海域内2个实际软弱场地模型进行非线性地震反应分析,通过对比时域非线性与频域等效线性化方法得到的时程、反应谱及傅里叶谱,从而提出更加真实更加可靠的海底泥面的设计地震动参数。研究成果对于今后开展海域软弱场地非线性地震反应分析方法的研究工作有一定的参考价值,对于指导我国海洋工程的抗震设防要求、提高海域设计地震动参数精度有一定的理论意义和现实意义。

Due to the characteristic of high nonlinearity,true response of seabed soft soil cannot be adequately reflected by methods based on equivalent linear model in frequency domain. For estimating the nonlinear seismic response more exactly,it is recommended to a true nonlinear method in time domain fitting G / G0-γ curve and λ-γ curve,and using it to 1D nonlinear seismic response analysis of soil layers on two real bores in Bohai seafloor. After comparing the time history,response spectrum,and fourier spectrum obtained from the two methods,more realistic and more reliable design ground motion parameters were proposed. With some reference value for future research on seabed soft soil nonlinear seismic response analysis,the results also show significance,both theoretically and practically,in guiding our ocean engineering requirements for seismic resistance,as well as improving the accuracy of marine design ground motion parameters.