地铁车站结构邻近土体动应力振动台试验研究
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摘要
研究地铁车站在地震中的响应对于地铁建设和安全运营非常重要。针对北京地区的地质条件和典型的地铁车站结构进行了大型振动台试验,对动土应力时程进行了分析,得出如下结论:埋深小于结构顶板和埋深大于结构底板的土中动土应力不随输入波强度与埋深变化而变化;在输入波强度低时,侧墙上各点的动土压力相等;在输入波强度高时,侧墙上各点的动土压力随输入波强度的增高而逐渐增大,且动土压力变化幅值随埋深增加而不断增加。通过以上分析,说明在地震强度小时,地下结构对土的水平向动应力影响很小,在地震强度大时,因地下结构的修建进行的开挖削弱了土体,其对土的水平向动应力影响变大。作者还对对结构底板的水平向动切应力进行了拟合,发现:底板的动切应力呈梯形分布,中点处最大,两个端点处最小;底板各点的动切应力随地震波强度的增加呈指数函数增加。为应用方便将底板中点的动切应力与地震波加速度峰值之间的关系简化为:当地震波峰值加速度不大于0.4 g时,峰值切应力为常数;当地震波峰值加速度大于0.4 g时,峰值切应力为直线分布。
It is important to study the dynamic response of underground structure during the strong earthquake for the metro construction and its safe management.The shaking table model test is made to the typical subway station structure in soil with specific concerns to the geological conditions of Beijing.Based on the analysis of the dynamic soil stress-time history curve around the subway station structure,the following conclusions are drawn: the horizontal dynamic stress peaks are constant in soil above the top slab and under the bottom slab;in soil at the side slab,when the input earthquake wave intensity is low,the horizontal dynamic stress peak is constant and small,and when the input earthquake wave intensity is high,the dynamic stress peak increases quickly with the rise of the depth;at the bottom slab,the dynamic stress is distributed in trapezoid form with the largest one at the center and the least one at its two ends.Based on above analysis,it is found that: when the earthquake intensity is low,the underground structure exerts a little influence on the horizontal dynamic soil stress and vise versa,due to that the excavation weakened the soil stiffness.With the rise of the input earthquake wave intensity,the dynamic shear stress at the slab increases in exponential function.For application convenience,this function is simplified: when the acceleration of earthquake peak is less than 0.4g,the shear stress peak will be constant and when it is larger than 0.4g,the shear stress peak increases linearly.
It is important to study the dynamic response of underground structure during the strong earthquake for the metro construction and its safe management.The shaking table model test is made to the typical subway station structure in soil with specific concerns to the geological conditions of Beijing.Based on the analysis of the dynamic soil stress-time history curve around the subway station structure,the following conclusions are drawn: the horizontal dynamic stress peaks are constant in soil above the top slab and under the bottom slab;in soil at the side slab,when the input earthquake wave intensity is low,the horizontal dynamic stress peak is constant and small,and when the input earthquake wave intensity is high,the dynamic stress peak increases quickly with the rise of the depth;at the bottom slab,the dynamic stress is distributed in trapezoid form with the largest one at the center and the least one at its two ends.Based on above analysis,it is found that: when the earthquake intensity is low,the underground structure exerts a little influence on the horizontal dynamic soil stress and vise versa,due to that the excavation weakened the soil stiffness.With the rise of the input earthquake wave intensity,the dynamic shear stress at the slab increases in exponential function.For application convenience,this function is simplified: when the acceleration of earthquake peak is less than 0.4g,the shear stress peak will be constant and when it is larger than 0.4g,the shear stress peak increases linearly.
引文
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[2]林皋,梁青愧.地下结构的抗震设计[J].土木工程学报,1996,23(1):15-23.(Lin Gao,Liang Qinhuai.Aseismic design of underground structures[J].Journal ofCivil Engineering,1996,23(1):15-23.(in Chinese))
[3]林志,朱合华,杨超,等.盾构区间隧道衬砌结构的抗震计算[J].同济大学学报,2004,32(5),:607-611.(Lin Zhi,Zhu Hehua,Yang Chao,et al.Aseismic cal-culation on the lining structure of the shielding zone tun-nel[J].Journal of Tongji University,2004,32(5):607-611.(in Chinese))
[4]尚昊,郭志昆,张武刚.大断面地下结构抗震模型试验[J].岩土工程界,2002,5(10):60-62.(ShangHao,Guo Zhikun,Zhang Wugang.Seismic model teston the large-section underground structure[J].Geo-engineering,2002,5(10):60-62.(in Chinese))
[5]宫必宁,赵大鹏.地下结构与土动力相互作用试验研究[J].地下空间,2002,22(4):320-326.(Gong Bi-ning,Zhao Dapeng.Test study on the soil and under-ground structure interaction[J].Underground Space,2002,22(4):320-326.(in Chinese))
[6]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.Subway stationmodel shaking table test study[D].Shanghai:TongjiUniversity,2002.(in Chinese))
[7]陈国兴,庄海洋,杜修力,等.土-地铁车站结构动力相互作用大型振动台模型试验研究[J].地震工程与工程振动,2007,27(2):62-67.(Chen Guoxing,Zhuang Haiyang,Du Xiuli,et al.Soil-subway stationstructure interaction shaking table model test research[J].Earthquake Engineering and Engineering Vibra-tion,2007,27(2):62-67.(in Chinese))
[8]边金,陶连金,张印涛,等.地下结构抗震设计方法的比较与分析[J].现代隧道技术,2008,45(6):50-55.(Bian Jin.Tao Lianjin.Zhang Yintao,et al.Com-parison and analysis of the aseismic design methods onthe underground structure[J].Modern Tunnel Technol-ogy.2008,45(6):50-55.(in Chinese))
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