地下结构地震反应规范计算方法的对比分析

Comparison of Calculation Methods for Seismic Responseof Underground Structures in Design Codes

摘要:

随着地下空间大规模开发利用，地震灾害对其造成的潜在威胁不容忽视。基于《城市轨道交通结构抗震设计规范（GB50909—2014）》和《地下铁道建筑结构抗震设计规范（DG/TJ08—2064—2009）》建议的分析方法，选取惯性力法、反应位移法（国家规范法、上海规范法）、动力时程方法（线弹性方法、等效线性化方法）三类共5种计算方法，以典型两层双柱三跨地铁车站结构为分析对象进行地震反应的对比验算，对上述计算方法的适应性进行评价。分析结果表明，与动力时程方法相比较，惯性力法计算得到的侧墙剪力值偏大，中柱结果较为接近；对于反应位移法，国家规范方法和上海规范方法的计算模型略有不同，但两者计算结果基本相近，其中土体强制位移、集中地基弹簧、土体动剪切模量等参数取值对计算结果影响显著；对于动力时程方法，线弹性方法和等效线性化方法的结果较为接近，且变化趋势相同。

Abstract:

Large-scale development and utilization of underground space is threatened by earthquake. For practical approaches of seismic analysis in the Code for Seismic Design of Subway Structures (DG/TJ08-2064-2009) and Code for Seismic Design of Urban Rail Transit Structures (GB50909-2014), this paper briefly introduces the principles, calculation processes of the codes, and the comparisons between them. Earthquake response analyses of a 2D subway station structure with two stories, double columns, and three spans are calculated by some methods:inertial force method, two response displacement methods (methods in national code and Shanghai code), and two dynamic time-history analysis methods with different assumptions (considering linear elasticity property and equivalent linearization of soil particles). The nonlinear dynamic characteristics of soil obtained using dynamic time-history analysis method are similar to those obtained using an equivalent linearization method. The maximum internal forces of structures with different methods are mainly compared. The applicabilities are summarized and evaluated as follows. The analyses show that compared with dynamic time-history analysis method, the inertial force method has more accurate column results and a bit larger shear force on the left side of the wall. Considering the response displacement method, there are some slight differences between the national code and Shanghai code, even if calculations are basically consistent. The results of response displacement method are mainly influenced by forced displacement, equivalent hypothetical spring in foundation, and the dynamic shear modulus of soil layers. For the dynamic time-history analysis method, the results of linear elastic assumption are close to and have the same trend as those of the equivalent linear one. Combining analysis processes with calculation errors, inertial force method is simple but inaccurate, because it is too simplified. The point of soil-structure interaction is well represented in the response displacement method. The above two methods are suitable for seismic response of simple underground structures. Although the dynamic time-history analysis method requires much calculations, it considers more comprehensive factors and has a wide range of applications.