双向地震作用对可液化倾斜场地-桩基-结构地震响应的影响研究  

Influence of bidirectional seismic action on seismic response of pile foundation-structure in liquefiable inclined soil

作　　者：苏卓林 贾科敏 许成顺[1] 豆鹏飞 张小玲[1] SU Zhuolin;JIA Kemin;XU Chengshun;DOU Pengfei;ZHANG Xiaoling(Key Laboratory of Urban Security and Disaster Engineering of the Ministry of Education,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学城市与工程安全减灾教育部重点实验室,北京100124

出　　处：《建筑结构学报》2023年第7期15-26,共12页Journal of Building Structures

基　　金：国家自然科学基金面上项目(52078016)。

摘　　要：为研究水平竖向双向地震作用对倾斜液化场地-桩基-结构体系地震响应的影响,基于Biot多孔介质理论,将饱和砂土模拟为固液完全耦合的两相介质,采用多屈服面塑性本构模型模拟饱和砂土的地震响应,在OpenSees软件中建立了可液化倾斜场地-桩基-桥梁结构体系有限元模型,并与已经完成的液化倾斜场地-群桩基础-上部结构体系大型振动台试验结果进行对比,验证了数值模型的可靠性。在此基础上,建立了典型液化倾斜场地-桩基-桥梁结构体系的数值模型,探讨了水平单向和水平竖向双向地震作用下体系的地震响应规律。结果表明:相比水平单一方向地震输入,水平竖向地震耦合作用时,可液化土的孔隙水压力震荡强烈,可液化层土体的侧向永久位移明显增加,尤其是在饱和砂土中上层的位置;水平竖向双向地震作用下,桩的破坏更显著且易损伤位置增多,桩基峰值曲率最大可增加128%,可液化层中部的桩身侧向位移增加约30%;此外,增加桩的配筋率可以有效限制土体侧向位移从而降低桩的破坏程度;竖向地震作用增大了上部结构的惯性效应,使得桥墩墩底峰值曲率增大约100%,加剧了桥墩墩底的损伤程度。因此,在液化倾斜场地中桩基础的抗震设计时应考虑竖向地震作用的影响。To investigate the seismic response of the pile-structure system in inclined liquefiable soil under horizontal and vertical coupling excitations,this paper adopted the Biot porous medium theory to simulate the saturated sand as a solid-liquid fully coupled two-phase medium.The multi-yield surface plastic constitutive model was used to simulate the seismic response of the saturated sand.The finite element model of the liquefiable inclined site-pile foundation-bridge structural system was established using OpenSees.The shaking table test results were compared to verify the reliability of the numerical model.On this basis,a numerical model of pile foundation-bridge structural system in typical liquefiable soil was established,and the seismic responses of the system under horizontal one-way and horizontal and vertical coupling earthquakes were discussed.The results indicate that compared with the horizontal single-direction seismic input,the pore water pressure of the liquefiable soil oscillates prominently when the horizontal and vertical seismic coupling acts.Furthermore,the permanent lateral displacement of the liquefiable layer soil increases significantly,especially in the shallow and middle layers of the saturated sandy soil.Under the horizontal and vertical two-way earthquakes,the damage of the pile is more significant,and the vulnerable positions are increased.The maximum curvature of the pile can be increased by 128%.The lateral displacement of the pile in the middle of the liquefiable layer can be increased by about 30%.In addition,increasing the reinforcement ratio of the pile can effectively curb the lateral displacement of soil and reduce the damage degree of the pile.The vertical seismic action increases the inertia effect of the superstructure,increases the peak curvature of the pier bottom by about 100%,and intensifies the damage degree of the pier bottom.Therefore,the seismic design of the pile foundation built in the liquefied lateral expansion site should consider the influence of vertical seismic

关 键 词：可液化倾斜场地 水平竖向双向地震 数值模拟 地震响应 

分 类 号：TU311.41[建筑科学—结构工程]