Research on improved model of time-frequency domain conversion for infinite-domain dynamic model of foundations considering time series characteristics
LI Jianbo，CHEN Miaomiao，LIN Gao
(State Key Laboratory of Coastal and Offshore Engineering，Dalian University of Technology，Dalian，Liaoning 116024，China)
Abstract：It is difficult to directly solve the time-domain impulse response function of foundations in complex sites. Establishing the high-precision conversion relationship between the frequency domain dynamic stiffness curve and the time domain model of the foundations is a hot issue of current concerns. Based on the traveling wave superposition principle and considering the singularity of the dynamic stiffness，the Nakamura model that transforms the frequency domain dynamic stiffness to the time domain impulse response function is improved. The repeated phase angles and the singular terms in the classic Nakamura model often lead to unstable numerical results. In order to solve these problems，the reasons for the repeated phase angles are analyzed，the distribution law of the repeated phase angles is revealed through formula derivation，and a simple and feasible micro-adjustment method is proposed to avoid the occurrence of the repeated phase angles，making the improved method more robust. In addition，due to the singular terms contained in the frequency domain dynamic stiffness，it is impossible to use the numerical Fourier transform to directly convert to the time domain. The strategy of stripping the singular terms and fitting only the conventional terms enables the time domain impulse response function to achieve a higher fitting precision. Taking the analytical solutions of a cavity in an elastic full space and a semi-infinite rod in an elastic half space as examples，it is verified that the improved method can obtain a high-precision time-domain impulse response function and improve the calculation stability. A case study illustrates the applicability of the improved method in engineering application.
李建波，陈苗苗，林 皋. 考虑行波时序特征的地基无限域动力模型的时频域转换改进模型研究[J]. 岩石力学与工程学报, 2021, 40(12): 2584-2592.
LI Jianbo，CHEN Miaomiao，LIN Gao. Research on improved model of time-frequency domain conversion for infinite-domain dynamic model of foundations considering time series characteristics. , 2021, 40(12): 2584-2592.
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2021, Vol. 40 
