城市密集建筑群对沉积谷地地震动放大效应的影响
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摘要
采用有限元模拟方法建立了建筑群-沉积谷地二维模型,并在土体截断边界上施加粘弹性人工边界,在频域与时域中对比分析此体系和单独沉积谷地的地震反应,观察地震时沉积谷地与建筑群之间的动力相互作用规律。分析表明,沉积谷地中建筑群对谷地本身的地震反应具有显著影响。入射波频率较低时,由于共振效应的存在,在部分区域处建筑群-沉积谷地体系的地表位移响应幅值会大于单独沉积谷地,但随着入射波频率的增加,建筑群的存在又会对地震反应产生明显的减弱效果;建筑群对谷地的影响还与建筑高度和建筑间距有关,且不同位置处的响应也存在很大差异。计算结果可为沉积谷地中设防烈度的设置以及工程抗震设计提供部分理论依据。
A two-dimensional model of a buildings-alluvial valley system is established using the finite-element method, and the viscoelastic artificial boundary is applied on the truncated boundary of the soil body. By comparing and analyzing the seismic responses of the buildings-alluvial valley system and the single alluvial valley both in the frequency domain and the time domain, the dynamic interaction between alluvial valley and buildings under earthquake is studied. The results show that because of the resonance effect under low-frequency incident waves, the surface displacement response amplitude of the buildings-alluvial valley system is larger than that of the single alluvial valley in some areas. As the frequency of the incident wave increases, the buildings will have a significant weakening effect on the seismic response. In addition, the impact of the buildings on the valley is also related to the building height and building spacing, and the responses at different locations are significantly different. The numerical results can provide a theoretical basis for the setting of fortification intensity in alluvial valleys and the seismic design of projects.
A two-dimensional model of a buildings-alluvial valley system is established using the finite-element method, and the viscoelastic artificial boundary is applied on the truncated boundary of the soil body. By comparing and analyzing the seismic responses of the buildings-alluvial valley system and the single alluvial valley both in the frequency domain and the time domain, the dynamic interaction between alluvial valley and buildings under earthquake is studied. The results show that because of the resonance effect under low-frequency incident waves, the surface displacement response amplitude of the buildings-alluvial valley system is larger than that of the single alluvial valley in some areas. As the frequency of the incident wave increases, the buildings will have a significant weakening effect on the seismic response. In addition, the impact of the buildings on the valley is also related to the building height and building spacing, and the responses at different locations are significantly different. The numerical results can provide a theoretical basis for the setting of fortification intensity in alluvial valleys and the seismic design of projects.
引文
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[2] 王淮峰,楼梦麟,陈希,等.建筑群结构-土-结构相互作用的影响参数研究[J].同济大学学报(自然科学版),2013,41(4):510-514.WANG Huaifeng,LOU Menglin,CHEN Xi,et al.Parametric Study on Structure-Soil-Structure Interaction of High-Rise Buildings[J].Journal of Tongji University(Natural Science),2013,41(4):510-514.
[3] 古泉,彭伊,曾志弘,等.分析土和结构相互作用的一种实用耦合方法[J].地震工程学报,2015,37(3):845-850.GU Quan,PENG Yi,ZENG Zhihong,et al.A Practical Coupling Method for Analyzing Soil-Structure Interaction[J].China Earthquake Engineering Journal,2015,37(3):845-850.
[4] 刘铁林,栾宇,钟伟.土-建筑群动力相互作用的数值模拟[J].工程力学,2012,29(A01):53-56.LIU Tielin,LUAN Yu,ZHONG Wei.Numerical Simulation of Dynamic Interactions between Soil and Buildings[J].Engineering Mechanics,2012,29(A01):53-56.
[5] SAHAR D,NARAYAN J P,KUMAR N.Study of Role of Basin Shape in the Site-city Interaction Effects on the Ground Motion Characteristics[J].Natural Hazards,2015,75:1167-1186.
[6] SANTANA A,AZNáREZ J J,PADRóN L A,et al.A BEM-FEM Model for the Dynamic Analysis of Building Structures Founded on Viscoelastic or Poroelastic Soils[J].Bulletin of Earthquake Engineering,2016,14(1):115-138.
[7] CHEN Q J,LI W T.Effects of a Group of High-Rise Structures on Ground Motions under Seismic Excitation[J].Shock and Vibration,2015,(3):1-25.
[8] KATO B ,WANG G.Ground Motion Simulation in an Urban Environment Considering Site-city Interaction:A Case Study of Kowloon Station,Hong Kong[C].3rd Huixian International Forum on Earthquake Engineering for Young Researchers.United States:University of Illinois,Urbana-Champaign,2017.
[9] LU X Z,TIAN Y,WANG G,et al.A Numerical Coupling Scheme for Nonlinear Time History Analysis of Buildings on a Regional Scale Considering Site-City Interaction Effects[J].Earthquake Engineering & Structural Dynamics,2018,47(13):2708-2725.
[10] LYSMER J,KULEMEYER R L.Finite Dynamic Model for Infinite Media[J].Journal of Engineering Mechanics Division,1969,95(4):759-877.
[11] 廖振鹏.工程波动理论导论(2版)[M].北京:科学出版社,2002.LIAO Zhenpeng.Introduction to Wave Motion Theories in Engineering[M].Beijing:Science Press,2002.
[12] LIAO Z P,WONG H L.A Transmitting Boundary for the Numerical Simulation of Elastic Wave Propagation[J].International Journal of Soil Dynamics and Earthquake Engineering,1984,3(4):174-183.
[13] DEEKS A J,RANDOLPH M F.Axisymmetric Time-Domain Transmitting Boundaries[J].Journal of Engineering Mechanics,1994,120(1):25-42.
[14] 何建涛,马怀发,张伯艳,等.黏弹性人工边界地震动输入方法及实现[J].水利学报,2010,41(8):960-969.HE Jiantao,MA Huaifa,ZHANG Boyan,et al.Method and Realization of Seismic Motion Input of Viscous-Spring Boundary[J].Journal of Hydraulic Engineering,2010,41(8):960-969.
[15] 孙纬宇,欧尔峰,严松宏,等.基于黏弹性边界的地震动输入方法和边界条件选择研究[J].地震工程学报,2016,38(6):929-934.SUN Weiyu,OU Erfeng,YAN Songhong,et al.Earthquake Input Method and Selection of Boundary Conditions Based on Viscoelastic Boundaries[J].China Earthquake Engineering Journal,2016,38(6):929-934.
[16] 吴爽,赵志刚,裴强,等.基于粘弹性人工边界的地震动输入方法的研究[J].大连大学学报,2017,38(3):8-11.WU Shuang,ZHAO Zhigang,PEI Qiang,et al.Study on the Seismic Input Method of Viscoelastic Artificial Boundary Condition in Finite Element Software[J].Journal of Dalian University,2017,38(3):8-11.
[17] DRAVINSKI M,MOSSESSIAN T K.Scattering of Plane Harmonic Waves by Multiple Dipping Layers of Arbitrary Shape[M]//DRAVINSKI M,MOSSESSIAN T K.eds.Ground Motion and Engineering Seismology.Elsevier,1987:91-105.