黄土区地铁车站动力分析中的无限元传输边界

Infinite-element transmitting boundary in dynamic analysis of subway station in loess area

地铁地下结构有限元分析时,半无限域截断处的人工边界条件直接影响计算结果的可靠性.本文基于ABAQUS有限元分析软件,探讨地铁地下结构动力响应分析中固定边界、远置边界、粘弹性边界及无限元传输边界的实现方法;通过黄土介质振动响应分析,对黄土地区地铁车站动力响应分析中各种人工边界条件的模拟效果进行对比研究.结果显示,在黄土地区采用粘弹性边界和无限元传输边界均可有效控制波的反射干扰,模拟波动穿过人工边界面向半无限域传播的特征.与粘弹性边界相比,无限元传输边界使用有限单元模拟近场黄土,使用无限单元界模拟远场黄土介质,具有技术处理简单,计算成本低,精度高等特点.实例分析表明,在黄土地区地铁车站地震反应分析中采用有限元-无限元耦合的建模方法,具有较好的适用性.

The treatment for artificial boundary condition of semi-infinite region will directly influence the reliability of analysis results in finite element analysis of subway structures.Based on the finite element analysis software of ABAQUS,the implementation methods of fixed boundary,remote artificial boundary,viscous-spring boundary and infinite-element transmitting boundary were studied in the dynamic analysis of subway structures.By the vibration response analysis of loess medium,the reliability of artificial boundary conditions was comparatively studied.The results showed that the characteristics of seismic wave passing artificial boundary of semi-infinite region were simulated effectively in loess area by using viscous-spring boundary and infinite-element transmitting boundary,due to the interference of reflection on the boundary being weakened significantly.With the infinite-element transmitting boundary is use,the near-field and far-field loess medium were simulated by finite elements and infinite elements respectively.This presented the characters of simple technology,low computational cost and high precision compared with viscous-spring boundary.Then,the engineering example of simulating the semi-infinite region of loess medium using the infinite-element transmitting boundary was analyzed,and the applicability of coupling finite element with infinite element in the seismic analysis of subway station was studied for loess area.