Ⅲ类场地条件下场地特性对反应位移法的影响评价

Evaluation on Response Displacement Method for Shield Tunnel under Ⅲ Site Condition Characterization

以二维动力时程分析法为基准,分别计算在长、短周期水平地震动作用下两种Ⅲ类场地下的地铁盾构隧道结构产生的内力和变形,对现行反应位移法进行适用性评价。结果表明,隧道位于短周期地震动为主要成分的Ⅲ类场地时,反应位移法计算得到的内力增量要略大于有限元动力时程法的计算结果。当隧道位于长周期地震动为主要成分的Ⅲ类场地时,反应位移法的内力增量计算结果较动力时程法的结果偏小。并且Ⅲ类场地长周期地震动作用下,动力时程法计算得到的竖向直径变形率远大于反应位移法。

This paper concentrates on using the response displacement method proposed by the current Code for Seismic Design of Urban Rail Transit Structure to conduct two-dimensional lateral seismic calculation. Assumed the same depth, the calculated internal force and deformation of two tunnels located in the site condition Ⅲ under different period horizontal earthquake ground motions. The results by using the dynamic time-history method would be given as reference standard to evaluate the applicability and accuracy of the current response displacement method. When the tunnel is located in a short period seismic motion as a main component of the site condition Ⅲ, the results of stress increment calculated by the response displacement method are slightly larger than those of the dynamic time-history method. Oppositely, the results of stress increment calculated by the response displacement method are slightly smaller than those of the dynamic time- history method. Besides,the vertical diameter deformation rate by using the dynamic time-history method is much larger than the response displacement method does under a long period seismic motion in the site condition Ⅲ.