地下工程抗震分析中地震动输入方法研究

STUDY OF METHOD OF EARTHQUKAE INPUT IN ASEISMIC ANALYSIS FOR UNDERGROUND ENGINEERING

提出一种新的基于无限元人工边界的合理的地震动输入方法,该方法考虑到地层的辐射阻尼和地震波在地层中的反射和散射,采用波场分解的方法给出地震波从底面垂直入射时不同边界面上的等效地震荷载的计算公式。同时进行算例考证,结果表明,采用固定边界计算结果会出现失真的扰动,而采用该方法其结果与解析解吻合得比较好。最后将该方法用于西藏嘎龙拉隧道三维地震动力分析中,得到一些有意义的结论。

A new earthquake input method based on infinite element dynamic artificial boundary is proposed.In this new method,radiation damping of the strata and reflection,scattering of the seismic wave in the strata are both considered;and equivalent earthquake load formulae in different boundary surfaces for seismic waves vertically incident from the bottom of computational domain are deduced by using the wave field separation method. Meanwhile,a numerical example is given to verify the validity and accuracy of the method.The results show that the distortional disturbance appears in the result adopting fixed boundary,whereas the results using the method proposed tally with the results using analytical method well so as to prove the effectiveness of the presented method.At last,the new earthquake input method is applied to the three-dimensional aseismic analysis of Galongla tunnel,and some meaningful conclusions are drawn.