某大型地下停车场强地震反应数值模拟分析

近年来全球范围内的地震灾害表明,地下结构在强地震作用下并没有预料的安全,针对铁路和公路隧道、地铁车站和区间盾构隧道的抗震设计研究已经有一定的基础,而对于大型公用地下工程如地下停车场、地下变电站、地下商场等的研究并不多,对此类地下结构的抗震性能研究意义重大。本文在地下结构的震害和岩土非线性动力计算方法研究的基础上,采用数值方法,对某大型地下结构进行了完全非线性地震动力时程分析,采用二次开发的土体非线性动力本构模型,模拟土在循环荷载作用下的动力特性。采用100年超越概率2%的强地震波作为地震动输入,对某大型地下停车场的地震反应进行了分析,重点分析结构的内力发展过程,并与三维等效地震荷载法计算结果进行对比。数值模拟结果能够合理地计算地下结构的内力和变形,能够很好地标识出地下结构的薄弱部分,对地下结构的抗震设计有很好的指导作用,可以为其他大型地下结构抗震计算的参考。

Seismic analysis of a large-scale underground parking

The seismic hazards all around the world in recent years show that underground structures are not as safe as supposed before. There are a lot of research on tunnels of railway and highway,subway station and tunnels,but for large-scale underground structures e. g. underground parking,underground electric substation,underground store,the research is very insufficient. So it＇s worthwhile to study how these underground structures act in earthquake. Based on the comprehensive study of available seismic hazards and the algorithm for geotechnical earthquake engineering,the program FLAC3D which is based on FDM（ Finite Difference Method） is used to take numerical analysis. A dynamic nonlinear model implemented in FLAC3D is used to model the characteristics of soils under cyclic loadings. The dynamic elastic model is used to model the characteristics of the reinforced concrete under cyclic loadings. One kind of earthquake acceleration histories is used to simulate the seismic response of a underground parking,which has 2% probability in future 100 years respectively. Emphasis on the internal force and damage evolution process,the analysis show that weak parts of the underground structures can be found by numerical simulation,by monitor the internal force and damage evolution process. The simulation procedure can be referred by other design of similar large-scale underground structures.