超大型地下结构系统地震响应高性能弹塑性流固耦合分析

High-performance dynamic elastoplastic solid-fluid coupled analysis of very large underground structural system in liquefiable site

随着城市地下空间开发进行加快,地下结构的抗震安全问题日益受到重视。为了研究饱和土层,尤其是可液化场地中超大型地下结构的地震响应,必须解决高性能计算、弹塑性本构模型、流固耦合等关键问题。该文基于高性能数值仿真平台GEOSX,开发一套高性能弹塑性流固耦合分析方法。以北京城市副中心站综合交通枢纽为例,采用砂土液化大变形模型进行动力弹塑性流固耦合分析,计算规模超千万自由度。计算结果表明,所开发的分析方法具有较高的并行计算效率,可以实现可液化场地地下结构系统的大规模高效弹塑性流固耦合模拟。对于这一主要处于饱和砂土地层中的超大型地下结构系统,在基本地震作用下,饱和砂土层的最大超静孔压比达到约0.5,产生较为明显的弱化;结构地震层间位移角和内力均满足规范要求,由于存在开洞等断面变化,结构响应三维效应明显;由于与地下结构相连的地上结构相对较小,地上结构对地下结构地震响应影响有限。

With the rapid development of urban underground space,the seismic safety of underground structures is becoming increasingly important.To study the seismic safety of very large underground structures in saturated sandy soil sites,especially in liquefiable sites,key technologies including high-performance computing,elastoplastic constitutive model and solid-fluid coupled analysis must be developed.In this study,a set of high-performance solid-fluid coupled dynamic analysis methods are developed based on the GEOSX platform.With the Beijing Municipal Administrative Center Station Transportation Junction Complex taken as an example,the dynamic elastoplastic solid-fluid coupled analysis,in which the problem size is over 10 million degrees of freedom,is carried out using the CycLiq constitutive model.The calculation results show that the proposed analysis method can produce the efficient simulation of very large underground structure system in liquefiable site.For the very large underground structure mostly embedded in saturated sand layers,the maximum excess pore pressure ratio of the saturated sand layer can reach about 0.5 under the earthquake input with 10%probability of exceedance within 50 years;the drift ratio and internal forces of the underground structure are within the design requirements,while the3D effect of the structure is evident due to the complex form of the structure;as the aboveground structure connected to the underground part is comparatively small in size,the influence of the aboveground structure on the seismic response of underground structure is limited.