1.Department of Civil Engineering, Nanjing Institute of Technology, Nanjing 211167, China;
2.Institute of Geotechnical Engineering, Nanjing Tech University, Nanjing 210009, China;
3.School of Civil Engineering and Architecture, East China Jiaotong University,Nanchang 330013, China
Abstract：By controlling the intensity and duration of input ground motions, this paper proposes a shaking table test method for pile foundation isolated structure on a variable-stiffness foundation. On this basis, combined with the completed shaking table model tests of isolated structures on different foundations, the influence of the foundation stiffness change on the dynamic characteristics of the pile group foundation of the isolated structure is also analyzed. The results show that the relative stiffness ratio of structure to soil and the strength of the input ground motion significantly affect the moment response of the pile group foundation of the isolated structure. With the increase of the relative stiffness ratio of structure to soil under strong earthquake motion, the upper moment response amplitudes of the middle piles in the pile group foundation of isolated structure grow remarkably, while the lower moment amplitude of the middle pile is relatively small. When the peak acceleration of the input motion and the relative stiffness ratio of structure to soil are greater than a certain limit, the seismic settlement of the pile group foundation increases significantly, and the rotation response of the pile group foundation cap is strong. Meanwhile, the horizontal displacement of grouped pile foundation pile top appears obvious unilateral cumulative horizontal displacement after the main earthquake. It indicates that the pile top of the pile group foundation of the isolated structure tends to occur earthquake damage during the process of foundation stiffness change, while the joint action of the seismic settlement of the pile group foundation and strong rotation reaction of foundation cap may be the main reason for the sharp increase of the pile upper bending moment.
于旭1，单志承2，庄海洋3，陈国兴2. 变刚度地基上隔震结构群桩基础动力响应试验研究[J]. 振动与冲击, 2024, 43(2): 208-218.
YU Xu1,SHAN Zhicheng2,ZHUANG Haiyang3,CHEN Guoxing2. Experimental study on the dynamic characteristics of the pile group foundation of a base-isolated structure on variable stiffness groud . JOURNAL OF VIBRATION AND SHOCK, 2024, 43(2): 208-218.
[1] Cubrinovski M, Ishihara K, Furukawazono K. Analysis of Full-Scale Tests of Piles in Deposits Subjected to Liquefaction[C]. 2nd International Conference on Earthquake Geotechnical Engineering, 1999:377-382.
[2] Yao S, Kobayashi K, Yoshida N, et al. Interactive Behavior of Soil-Pile-Superstructure System in Transient State to Liquefaction by Means of Large Shake Table Tests [J]. Soil Dynamics and Earthquake Engineering, 2004, 24(5): 397-409.
[3] Motamed R, Towhata I, Honda T, et al. Pile group response to liquefaction-induced lateral spreading: E-defense large shake table test[J]. Soil Dynamics and Earthquake Engineering, 2013, 51(3): 35–46.
[4] Klar A, Frydman S, Baker R. Seismic analysis of infinite pile groups in liquefiable soil [J]. Soil Dynamics and Earthquake Engineering, 2004, 24(8): 565-575.
[5] Leung Y F, Soga K. Lehane B M, et al. Role of linear elasticity in pile group analysis and load test interpretation [J]. Journal of Geotechnical and Geoenvironmental Engineering, 2010, 136(12): 1686-1694.
[6] Liyanapathirana D S, Poulos H G. Seismic lateral response of piles in liquefying soil [J]. J Geotech Geoenviron Eng, 2005, 131: 1466-1479.
[7] Zhuang Haiyang, Yu Xu, Zhu Chao, et al. Shaking table tests for the seismic response of a base-isolated structure with the SSI effect [J]. Soil Dynamics and Earthquake Engineering, 2014, 67(6): 208-218.
[8] 于旭, 庄海洋, 朱超. 基于模型试验的软夹层地基与刚性地基上隔震结构体系耗能特性分析[J]. 振动与冲击,2016, 35(10) : 73-82.
Yu Xu, Zhuang-haiyang, Zhu Chao. Analysis on the energy dissipation of isolated structures on rigid foundation and soft interlayer soil foundation based on model test[J]. Journal of Vibration and Shock, 2016, 35(10) : 73-82.
[9] 王建宁, 庄海洋, 马国伟, 等. 软土层场地复杂地铁地下车站结构地震反应分析[J]. 振动与冲击, 2019, 38(19): 115-122.
Wang Jian-ning, Zhuang-haiyang, Ma Guo-wei, et al. Seismic responses of a complicated subway underground station in soft soil layers[J]. Journal of Vibration and Shock, 2019, 38(19) : 115-122.
[10] 王建宁, 付继赛, 庄海洋, 等. 可液化场地中复杂异跨地铁地下车站结构的地震反应分析[J]. 振动与冲击, 2020, 39(7): 172-179.
Wang Jian-ning, Fu Ji-sai, Zhuang-haiyang, et al. Seismic response analysis of complex subway station structure with unequal-span in liquefiable foundation [J]. Journal of Vibration and Shock, 2020, 39(7): 172-179.
[11] 于旭. 考虑土与结构相互作用的隔震结构体系性能研究[D]. 南京工业大学, 2009.
YU Xu. Performance Research on Seismic Isolated Structure System Considering Soil-Structure Dynamic Interaction[D]. Nanjing University of Technology,2009.
[12] 于旭,宰金珉,王志华.铅芯橡胶支座隔震钢框架结构体系振动台模型试验研究[J].世界地震工程，2010，26（03）：30-36.
YU Xu, ZAI Jin-ming, WANG Zhi-hua. Shaking table tests on the model of a steel-framed structure system with lead core rubber bearing isolations[J].World Earthquake Engineering, 2010，26（03）：30-36.
[13] 于旭, 庄海洋, 朱超, 等. 软夹层地基上多层隔震结构模型振动台试验研究[J]. 振动与冲击,2015, 34(24) : 104-110.
Yu Xu, Zhuang-haiyang, Zhu Chao, et al. Shaking table test on the modal of a multi-story isolated structure on the ground with softer interlayer[J]. Journal of Vibration and Shock, 2015, 34(24) : 104-110.
[14] 李昌平, 刘伟庆, 王曙光等. 软土地基上高层隔震结构模型振动台试验研究[J]. 建筑结构学报, 2013, 34(7): 72-78.
LI Chang-ping, LIU Wei-qing, WANG Shu-guang, et al.Shaking table test on high-rise isolated strucure on soft soil foundation[J].Journal of Building Structures.2013, 34(7): 72-78.
[15] 吴应雄，郑泽炜，颜桂云等. 远场长周期地震动下桩-土-层间隔震结构振动台试验研究[J]. 建筑结构学报, 2020，4（74）：1-12.
WU Ying-xiong, ZHENG Ze-wei, YAN Gui-yun, et al. Shaking table test of pile-soil inter-storey isolated structure under far-field long-period ground motion[J]. Journal of Building Structures. 2020, 4(74): 1-12.
[16] 许成顺, 豆鹏飞, 高畄成等. 地震动持时压缩比对可液化地基地震反应影响的振动台试验[J]. 岩土力学, 2019, 40(1): 147-155.
XU Cheng-shun, DOU Peng-fei, GAO Liu-cheng, et al. Shaking table test on effects of ground motion duration compression ratio on seismic response of liquefied foundation[J]. Rock and Soil Mechanics, 2019, 40(1): 147-155.
[17] Tso W, Zhu T, Heidebrecht A. Engineering implication of ground motion A/V ratio [J]. Soil Dynamics and Earthquake Engineering, 1992, 11(3): 133-144.
[18] 周燕国,沈 涛,王 越等.基督城易液化场地震后小应变剪切刚度演化规律研究[J]. 岩土工程学报, 2020, 42(8): 1411-1417.
ZHOU Yan-guo, SHEN Tao, WANG Yue, et al. Post-earthquake evolution of small-strain shear stiffness at liquefiable deposit in Christchurch[J]. Chinese Journal of Geotechnical Engineering, 2019, 40(1): 147-155.
[19] 叶斌，叶冠林，张锋.液化砂土地基刚度恢复过程的振动台试验[J].水利学报, 2012, 43(7): 877-882.
YE Bin，YE Guan-lin，ZHANG Feng. Shaking-table tests on the stiffness recovery process of liquefied sandy ground[J]. Shuili Xuebao. 2012, 43(7): 877-882.
[20] 李昌平,刘伟庆等. 土-隔震结构相互作用体系动力特性参数的简化分析方法[J].工程力学, 2013,30(07):173-179.
LI Chang-ping, LIU Wei-qing, et al..Simplified method for calculation dynamic characteristics of soil-isolated structure system[J]. Engineering Mechanics, 2013,30(07):173-179.
[21] Zhuang Haiyang, Fu Jisai, Yu Xu, et al. Earthquake responses of a base-isolated structure on a multi-layered soft soil foundation by using shaking table tests [J]. Engineering Structures, 2019,179:79-91.
[22] 刘星, 王睿, 张建民. 液化地基中群桩基础地震响应分析[J]. 岩土工程学报, 2015, 37(12): 200-205.
LIU Xing, WANG Rui, ZHANG Jian-min. Seismic response analysis of pile groups in liquefiable foundations [J]. Chinese Journal of Geotechnical Engineering, 2015, 37(12): 200-205.
