求解非均匀无限地基相互作用力的有限元时域阻尼抽取法

Finite element damping-extraction method for dynamic interaction time domain analysis of non-homogeneous unbounded rock

由于无限地基的动力效应较难确定,结构-地基的动力相互作用主要局限于频域分析,从而限制了非线性分析应用。阻尼抽取法(DSEM)通过在有限域内施以附加人工阻尼再移频抽取的办法可以有效地模拟非均匀无限粘弹性介质的动力特性,在结构-无限地基动力相互作用分析中有较好的应用前景。在此基础上,本文提出了DSEM进行结构-地基交界面相互作用力-位移时域分析的有限元逐步积分形式算法,并给出了具体实现公式,可以更好地适应工程有限元计算及与结构-地基相互作用程序结合的需要。最后,以实例形式论述了该方法良好的精度及实现中各个关键因素的影响。

The structure-soil dynamic interaction is mainly confined in frequency domain because of the difficulty of determination of dynamic effects of infinite medium on structural response, which makes most of the dynamic interaction analysis methods invalidated for nonlinear problems. Damping Extraction Method is an effective simple procedure, which can simulate the dynamic properties of non-homogeneous infinite medium by applying artificial damping and then shifting the frequency along frequency axis. Based on DSEM, it is convenient to get dynamic interaction force in time domain acting on interface between unbounded rock and structure. In this paper, an adaptive damping-extraction procedure is proposed for the dynamic interaction analysis of structure-unbounded rock system. The corresponding FE numerical implementation of the procedure in time domain is given by precise step-by-step time integration scheme, which can be conveniently combined to the existent FE program for dynamic soil-structure interaction in time domain. Some key factors in implementation are discussed. Several applications are presented and demonstrate satisfactory accuracy and excellent application prospect.