双向地震作用下液化水平和倾斜场地-桩基-桥梁结构地震反应的差异研究

Study on the difference of seismic responses of liquefied horizontal and inclined site-pile foundation-bridge structures under bidirectional earthquake excitations

根据已经完成的液化侧向扩展场地-群桩基础-上部结构体系大型振动台试验,在有限元软件OpenSees中建立了可液化倾斜场地振动台试验的有限元模型。通过与试验结果对比,验证了数值模型的可靠性。基于此,建立了典型水平和倾斜液化场地-桩基-桥梁结构体系的数值模型,讨论了双向地震作用下水平和倾斜场地体系地震响应的差异,结果表明:相比水平场地,倾斜场地超孔隙水压力在峰值阶段波动幅度更大,土体的侧向位移增加明显,尤其是在饱和砂土中部位置;倾斜场地中桩基础的破坏程度更大,可液化层中部桩基曲率最大可增大约13倍,桩身水平位移显著增加;而水平场地桥墩曲率比倾斜场地桥墩曲率大,建议在液化场地桩基设计中应考虑场地倾斜带来的影响。

According to the completed large-scale shaking table test of the liquefied lateral extension site-pile group foundation-superstructure system,the finite element model of the shaking table test of the liquefiable inclined site is established in the finite element software OpenSees.The reliability of the numerical model is verified by comparing with the experimental results.Based on this,numerical models of typical horizontal and inclined liquefaction site-pile foundation-bridge structural systems are established,and the difference in seismic response of horizontal and inclined site under bidirectional seismic excitation is discussed.The water pressure fluctuates more at the peak stage,and the lateral displacement of the soil increases significantly,especially in the middle of the saturated sand.The damage degree of the pile foundation in the inclined field is greater,and the maximum curvature of the pile foundation in the middle of the liquefiable layer can be increased by about approximately 13 times.The horizontal displacement of the pile body increases significantly.However,the curvature of the pier in the horizontal site is larger than that in the inclined site.It is suggested that the influence of the site inclination should be considered in the pile foundation design of the liquefaction site.