地震作用下大跨地下结构覆土地面动力响应

Dynamical response of ground covered by soil above the large span underground structure

为了给大跨地下结构地面上新建建筑的抗震设计提供依据,以某大跨地下拱壳结构工程为对象,采用通用有限元软件ANSYS,建立大跨地下拱壳结构-上覆土体的数值计算模型,依据结构抗震设防目标及场地条件,输入三向地震波进行地震反应分析。在结构覆土地面沿纵向和横向分别选取代表性节点,提取沿纵向线及沿横向线分布各点的地震反应,分析地面点的位移与应力响应,并结合建筑结构动力特性进行分析。研究结果表明:所建立的地下结构-上覆土体的地震反应分析模型能够反映出结构上覆土地面的动力反应特性;在靠近大跨地下拱壳结构的地面投影中心附近,竖向动力响应较为显著,不宜增建对竖向位移响应较敏感的结构;在综合利用大跨地下拱壳结构上部地面空间时,对地面增建建筑进行抗震设计时,分析结果可为增建建筑抗震分析的地震输入与分析提供理论指导,并为增建建筑位置的选取及结构选型提供依据。

To provide references for the seismic design of a new building on the ground over the large span underground structure, this paper chose a large span underground as the researching subject and established is a numerical model for the underground structure with overlaying soil by using the universal finite element software ANSYS. According to the site conditions and seismic fortification target, a seismic response analysis was conducted with three different directions seismic wave input. By selecting different representative nodes on the ground along the longitudinal and transverse directions over the air defense structure, their responses of displacement and stress were analyzed. The results show that the seismic response analysis model for the underground structure with the overlying soil can reflect the earth dynamic response. Near the projection center of large span underground arch shell structure, the vertical dynamic response is significant and thus structures should not be established when they are sensitive to the vertical displacement. When making comprehensive utilization of the upper floor space on the large span underground arch shell structure, the effects of underground structure of the new buildings should be considered for the seismic design. The results can provide a theoretical guidance for additional seismic structure analysis and for their location selection and structure selection. 7 figs, 17 refs.