双向地震作用下锯末混合土场地动力特性分析
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摘要
在北京工业大学振动台台阵系统上开展了一系列锯末混合土地基自由场振动台模型试验,试验中模型箱采用装配式连续体刚性模型箱,试验中输入地震动时程采用El Centro地震动记录、Taft地震动记录和天津地震动记录,地震动输入方向分为水平单向和水平双向。文中,重点考察了双向地震动输入下锯末混合土模型场地的动力特性及其变化规律,主要指标包括模型场地地震动反应的峰值加速度及其动力放大系数、加速度时程及其傅氏谱。试验结果表明:随着输入地震动强度的增大,同一测点反应的峰值加速度总体上在增大,而其加速度动力放大系数总体上呈现减小的趋势,反应的频谱组成从较高频率向较低频率移动;双向地震作用下锯末混合土模型场地的动力变化规律与单向地震作用下较为一致。
A series of shaking table tests on free-field sawdust-mixed clay site model under uniform earthquake excitation was conducted at the multiple shaking table testing systems in Beijing University of Technology. These tests were performed using a rigid prefabricated continuous model box. The test system was subjected to strong ground motions from El Centro record, Taft record, and Tianjin record. In this paper, we focused on the dynamic characteristics of the sawdust-mixed clay site model under bidirectional seismic actions, including the peak ground accelerations and their amplification factors, acceleration time histories, and their Fourier spectra for the site responses. The test results indicated that the increase in the intensity of ground motions increases the peak ground acceleration at the same test point; however, its acceleration amplification factor generally decreases and the main frequency components move from high to low frequency. The dynamic change rule of the sawdust-mixed clay site model under bidirectional seismic actions is consistent with that of one-directional seismic action.
A series of shaking table tests on free-field sawdust-mixed clay site model under uniform earthquake excitation was conducted at the multiple shaking table testing systems in Beijing University of Technology. These tests were performed using a rigid prefabricated continuous model box. The test system was subjected to strong ground motions from El Centro record, Taft record, and Tianjin record. In this paper, we focused on the dynamic characteristics of the sawdust-mixed clay site model under bidirectional seismic actions, including the peak ground accelerations and their amplification factors, acceleration time histories, and their Fourier spectra for the site responses. The test results indicated that the increase in the intensity of ground motions increases the peak ground acceleration at the same test point; however, its acceleration amplification factor generally decreases and the main frequency components move from high to low frequency. The dynamic change rule of the sawdust-mixed clay site model under bidirectional seismic actions is consistent with that of one-directional seismic action.
引文
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[2] 李霞,杜修力,路德春,等.双向水平地震作用下复杂地铁车站振动台模型试验的方案研究[J].防灾减灾工程学报,2015,35(3):321-327.LI Xia,DU Xiuli,LU Dechun,et al.Test Scheme Design for Shaking Table Model test of the Seismic Responses of the Complex Subway Station under Two Horizontal Directions Seismic Ground Motions.Journal of Disaster Prevention and Mitigation Engineering,2015,35(3):321-327.
[3] 史晓军.非一致地震激励地下综合管廊大型振动台试验研究[D].上海:同济大学,2008.SHI Xiaojun.Shaking Table Test on Utility Tunnel Under Non Uniform Seismic Excitations[D].Shanghai:Tongji University,2008.
[4] 吕西林,陈跃庆,陈波,等.结构-地基动力相互作用体系振动台模型试验研究[J].地震工程与工程振动,2000,20(4):20-29.LU Xilin,CHEN Yueqing,CHEN Bo,et al.A Study of Size Effect and Boundary Effect In Centrifugal Tests[J].Earthquake Engineering and Engineering Dynamics,2000,20(4):20-29.
[5] 季倩倩.地铁车站结构振动台模型试验研究[D].上海:同济大学,2002.JI Qianqian.Shaking Table Testing of Dynamic Soil-structure Interaction System[D].Shanghai:Tongji University,2002.
[6] 庄海洋.土-地下结构非线性动力相互作用及其大型振动台试验研究[D].南京:南京工业大学,2006.ZHUANG Haiyang.Study on Nonlinear Dynamic Soil-underground Structure Interaction and Its Large-size Shaking Table Test[D].Nanjing:Nanjing University of Technology,2006.
[7] CHEN Jun,SHI Xiaojun,LI Jie.Shaking Table Test of Utility Tunnel under Non-uniform Earthquake Wave Excitation[J].Soil Dynamics and Earthquake Engineering,2010,30(11):1400-1416.
[8] CHEN Guoxing,CHEN Su,ZUO Xi,et al.Shaking-table Tests and Numerical Simulations on a Subway Structure in Soft Soil[J].Soil Dynamics and Earthquake Engineering,2015,76:13-28.
[9] 陈红娟,闫维明,陈适才,等.小比例尺地下结构振动台试验模型土的设计与试验研究[J].地震工程与工程振动,2015,35(3):59-66.CHEN Hongjuan,YAN Weiming,CHEN Shicai,et al.Design and Experimental Research on Model Soil Used for Shaking Table Test of a Small Scale Underground Structure[J].Earthquake Engineering and Engineering Dynamics,2015,35(3):59-66.
[10] 陈红娟,李小军,闫维明,等.锯末混合土场地模型振动台试验研究[J].岩土工程学报,2017,39(11):2068-2077.CHEN Hongjuan,LI Xiaojun,YAN Weiming,et al.Shaking Table Tests on Sawdust-mixed Clay Site[J].Chinese Journal of Geotechnical Engineering,2017,39(11):2068-2077.
[11] 建筑抗震设计规范:GB 50011-2010[S].北京:中国建筑工业出版社,2010.Code for Seismic Design of Buildings:GB 50011-2010[S].Beijing:China Architecture and Building Press,2010.