含软弱夹层场地中地下结构抗震分析的反应位移法误差分析

Error analysis of response displacement method for seismic analysis of underground structures in site with weak interlayer

反应位移法是《城市轨道交通结构抗震设计规范》(GB 50909—2014)和《地下结构抗震设计标准》(GB/T51336—2018)在均质场地或简单成层场地中推荐使用的地下结构抗震简化分析方法,对于软弱夹层场地中其适用性有待商榷。本文基于ABAQUS有限元分析软件,构造了一般成层场地和含软弱夹层场地,采用土-地下结构整体动力时程分析方法获得了不同工况下地下结构的地震反应。以此为基准,评价分析了反应位移法在含软弱夹层场地中的适用性。结果表明:较一般成层场地而言,含软弱夹层场地中反应位移法所得出的结构反应与动力时程分析方法相比误差更大,在含软弱夹层场地中反应位移法适用性显著降低;从地基弹簧、土层剪力和结构惯性力三方面分析了误差产生的原因,给出了含软弱夹层场地中可使用整体式反应位移法提高计算精度的建议。

Response displacement method is a simplified seismic analysis method for underground structures recommended in Code for Seismic Design of Urban Rail Transit Structures(GB 50909—2014)and Standard for Seismic Design of Underground Structures(GB/T51336—2018)in homogeneous sites or simple layered sites.Its applicability needs to be discussed for the sites with weak interlayer.Based on ABAQUS finite element analysis software,this paper constructs the general layered site and the site with weak interlayer,and obtains the seismic response of the underground structure under different working conditions by using the soil-underground structure integral dynamic time-history analysis method.Based on this,the applicability of the response displacement method in the site with weak interlayer is evaluated and analyzed.The results show that compared with the general layered site,the error of the structural response obtained by the response displacement method in the site with weak interlayer is greater than that of the dynamic time-history analysis method,and the applicability of the response displacement method in the site with weak interlayer is significantly reduced;The causes of errors are analyzed from three aspects of foundation spring,soil shear force and structural inertia force,and suggestions are given that the integral response displacement method can be used to improve the calculation accuracy in the site with weak interlayer.