成层土场地地震效应的时程算法研究

Time-history algorithm for earthquake effect in layered-soil site

成层土场地是一类常见的建筑场地,覆盖土层的厚度、刚度、地层顺序等是影响地震动特性的主要因素,动力时程方法是分析此类问题的一个有效手段。但常规的动力时程方法计算求解复杂,不仅费时、费力,而且还可能因为算法的不稳定性而无法得到预期的结果。为了获得一种高效简便的动力时程算法,根据地震波在层状弹性介质中的传播原理,采用弹性波叠加方法,提出一种计算成层土场地地震响应的快速时程算法。该方法是一种级数逼近算法,无需剖分网格进行数值法计算,极大地提高了计算效率。应用该算法进行了模型试算,并将计算结果与相关文献进行对比,验证了此算法的正确性。

The overburden thickness, stiffness and the layered sequence are important factors which affect the vibration characteristic of ground motion. The dynamic time-history analysis is one of the useful methods to deal with such problems. However, when the dynamic time-history analysis is used, it will take much time to finish complicated numerical models and calculations. Sometimes it is impossible that any anticipated results can be obtained because of numerical algorithm instability. A fast time-history algorithm is put forward to calculate the layered site response effect according to the principle of seismic wave propagation of the layered elastic medium. As a series analytical approach algorithm, not a numerical method, the algorithm need not solve equations based on discrete network models, thus it can improve the calculative efficiency enormously. Finally, the feasibility and the usability of the algorithm are also proved by some test models.