Macro and Micro Analysis of Seismic Isolation Performance of Gravel Cushion Based on Discrete Element Method
-
摘要: 为研究非接触桩箱复合基础中碎石垫层隔震性能,采用颗粒流软件PFC3D对碎石垫层和沉箱进行模拟分析,从宏细观多角度对碎石垫层隔震性能进行分析。研究结果表明,竖向压力、垫层厚度对垫层隔震效果的影响较大;地震动加载过程中,垫层底部颗粒水平相对位移较大,垫层中上部颗粒水平相对位移较小,颗粒配位数及垫层孔隙率与碎石垫层隔震效果关系密切。Abstract: In order to study the seismic behavior of gravel cushion set up in the unconnected piles-caisson foundation, particle flow analysis software PFC3D was used to numerically simulate the shake table tests of gravel cushion and caisson and to study the seismic isolation performance of the gravel cushion from macro and micro view. The results shows that vertical pressure and thickness of the cushion have significant influence on isolation effect of the gravel cushion. During ground shaking loading, the horizontal relative displacement of particles at the bottom of the cushion is large, and the horizontal relative displacement of particles at the middle and upper part of the cushion is small. The changes of particle coordination number and cushion porosity are closely related to the seismic isolation effect of gravel cushion.
-
Key words:
- Gravel cushion /
- Foundation /
- Seismic isolation /
- Vibration reduction ratio /
- Particle /
- Discrete element method
-
表 1 垫层材料参数
Table 1. Bedding material parameters
参数 数值 粒径/mm 5.2,3.1~7.0,0.1~9.9 厚度/mm 20.0,30.0,40.0,60.0 阻尼比 0.055 黏聚力/kPa 0 重度/(kN·m−3) 16.51 颗粒间摩擦系数 0.57 侧限压缩模量/MPa 60.1 表 2 隔震率对比
Table 2. Comparison of isolation ratio
方案编号 垫层厚度/mm 压力/kPa 输入加速度/(m·s−2) 输出加速度/(m·s−2) 数值模拟减震率/% 文献减震率/% 误差/% 1-1 200 3.5 3.44 1.70 50.6 57.1 11.4 1-2 200 8.3 3.40 2.35 30.9 32.1 3.8 1-3 300 3.5 3.41 1.52 55.4 36.84 33.5 1-4 300 8.3 3.41 1.78 47.8 44.11 7.7 -
董学武, 周世忠, 2004. 希腊里翁-安蒂里翁大桥的设计与施工. 世界桥梁, 32(4): 1—4Dong X. W. , Zhou S. Z. , 2004. Design and construction of Rion-Antirion bridge in Greece. World Bridges, 32(4): 1—4. (in Chinese) 范立础, 王君杰, 2001. 桥梁抗震设计规范的现状与发展趋势. 地震工程与工程振动, 21(2): 70—77 doi: 10.3969/j.issn.1000-1301.2001.02.013Fan L. C. , Wang J. J. , 2001. Design code for earthquake-resistance of bridges: current situation and trend. Earthquake Engineering and Engineering Vibration, 21(2): 70—77. (in Chinese) doi: 10.3969/j.issn.1000-1301.2001.02.013 李志强, 栾阳, 张倩等, 2018. 碎石垫层隔震性能离散元数值分析. 公路, 63(1): 158—164. 刘宗华, 2012. 土耳其Izmit海湾大桥主塔基础设计与施工构思. 施工技术, 41(17): 11—13, 20Liu Z. H. , 2012. The conception of main tower foundation design and construction for Izmit bay bridge in turkey. Construction Technology, 41(17): 11—13, 20. (in Chinese) 吕伟华, 缪林昌, 2013. 刚性桩复合地基桩土应力比计算方法. 东南大学学报(自然科学版), 43(3): 624—628Lv W. H. , Miao L. C. , 2013. Calculation method of pile-soil stress ratio of rigid pile composite foundation. Journal of Southeast University (Natural Science Edition), 43(3): 624—628. (in Chinese) 南文文, 2015. 沉箱-垫层-桩复合深水基础水平承载性能研究. 南京: 东南大学, 43—51Nan W. W., 2015. Experimental study on bearing performance of caisson-cushion-pile deepwater composite foundation under lateral loads. Nanjing: Southeast University, 43—51. (in Chinese) 陶景晖, 梁书亭, 龚维明等, 2009. 高层建筑刚性桩复合地基承载受力性状研究. 东南大学学报(自然科学版), 39(S2): 238—245Tao J. H. , Liang S. T. , Gong W. M. , et al. , 2009. Study on bearing behavior of composite foundation with rigid pile for high-rise buildings. Journal of Southeast University (Natural Science Edition), 39(S2): 238—245. (in Chinese) 魏磊, 2013. 村镇建筑基础下碎石垫层隔震性能试验研究. 西安: 西安建筑科技大学, 21—35Wei L., 2013. An experimental research on seismic reduced function gravel layer under rural buildings foundation. Xi'an: Xi'an University of Architecture and Technology, 21—35. (in Chinese) 姚国伟, 2011. 复合地基褥垫层减震研究. 广州: 广州大学, 38—41Yao G. W., 2011. Study on seismic reduced function of composite foundation cushion. Guangzhou: Guangzhou University, 38—41. (in Chinese) 赵少伟, 窦远明, 郭蓉等, 2005. 基础下砂垫层隔震性能振动台试验研究. 河北工业大学学报, 34(3): 92—97 doi: 10.14081/j.cnki.hgdxb.2005.03.019Zhao S. W. , Dou Y. M. , Guo R. , et al. , 2005. An experimental study of isolating properties of sand cushion under the foundation by shaking table. Journal of Hebei University of Technology, 34(3): 92—97. (in Chinese) doi: 10.14081/j.cnki.hgdxb.2005.03.019 Anastasopoulos I. , Gazetas G. , Loli M. , et al. , 2010. Soil failure can be used for seismic protection of structures. Bulletin of Earthquake Engineering, 8(2): 309—326. doi: 10.1007/s10518-009-9145-2 Biesiadecki G. L., Dobry R., Leventis G. E., et al., 2004. Rion- Antirion Bridge foundations: A blend of design and construction innovation. In: Fifth International Conference on Case Histories in Geotechnical Engineering. New York: University of Missouri, 16. Combault J. , Pecker A. , Teyssandier J. P. , et al. , 2005. Rion-antirion bridge, Greece - concept, design, and construction. Structural Engineering International, 15(1): 22. doi: 10.2749/101686605777963387 Dobry R. , Pecker A. , Mavroeidis G. P. , et al. , 2003. Damping/global energy balance in FE model of bridge foundation lateral response. Soil Dynamics and Earthquake Engineering, 23(6): 483—495. doi: 10.1016/S0267-7261(03)00050-2 Lyngs J. H., Kasper T., Bertelsen K. S., 2013. Modelling of soil-structure interaction for seismic analyses of the Izmit Bay Bridge. In: Proceedings of the 18 th International Conference on Soil Mechanics and Geotechnical Engineering. Paris: ICSMGE, 763—768. Pfauth T. , Poling J. , 2017. Strain measurement in a specimen subjected to out-of-plane movement: Using an open-source digital image correlation-based tool. The Journal of Purdue Undergraduate Research, 7(1): 7. Yang D., Dobry R., Peck R. B., 2001. Foundation-soil-inclusion interaction modelling for rion-antirion bridge seismic analysis. In: Fourth International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics. New York: University of Missouri, 620.