虹口高原大桥的破坏机制分析
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摘要
基于汶川地震现场考察资料,分析了都江堰市虹口乡高原大桥的破坏机制。分析表明:大桥的破坏模式与震区大部分梁式桥因强烈的震动而破坏不同,场地效应表现更为明显,大桥地基与上部结构之间存在明显的刚度差,两者在地震作用下的位移不协调则是大桥被破坏的主要原因。地震期间桥面向右岸整体移位1.8 m。鉴于龙门山地区断层活动主要以逆冲压缩为主,灾后重建过程中桥址的选择尽量避开场地地质效应突出的区域,在桥梁结构类型的选择应因地制宜,简支梁桥应有必要的防落梁构造装置,以增强桥梁的容灾性。
Based on field reconnaissance,the damage mechanism of Gaoyuan bridge in Dujiangyan city was analyzed.Results showed that the failure mode of Gaoyuan bridge was quite different from most girder bridges failed by strong shake effect in the earthquake-hit area and site effect was more prominent.There existed a great stiffness difference between its structure and foundation,and its deformation inconformity was the major reason for its failure.The bridge face moved 1.8 meters to the right bank during the earthquake,which resulted in the falling down of its beam.Considering the thrust mode of Longmenshan faults,during the reconstruction the bridge site should be located in places with no strong site effect,bridge type should also conform with its geological background and necessary beam-fell prevention structure should also be taken into account to increase its seismic resistance capability.
Based on field reconnaissance,the damage mechanism of Gaoyuan bridge in Dujiangyan city was analyzed.Results showed that the failure mode of Gaoyuan bridge was quite different from most girder bridges failed by strong shake effect in the earthquake-hit area and site effect was more prominent.There existed a great stiffness difference between its structure and foundation,and its deformation inconformity was the major reason for its failure.The bridge face moved 1.8 meters to the right bank during the earthquake,which resulted in the falling down of its beam.Considering the thrust mode of Longmenshan faults,during the reconstruction the bridge site should be located in places with no strong site effect,bridge type should also conform with its geological background and necessary beam-fell prevention structure should also be taken into account to increase its seismic resistance capability.
引文
[1]Du Xiuli Han Qiang,Li Zhongxian,et al.The seismic dam-age of bridge in the 2008 Wenchuan Earthguake and lessonsfrom its damage[J].Journal of Beijing University of Tech-nology 2008,34(12):1207-1279.[杜修力,韩强,李忠献,等.“5.12”汶川地震中山公路桥梁震害及启示[J].北京工业大学学报,2008,34(12):1270-1279.]
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[7]地质剖面图[R].成都:中交第三公路工程局有限公司,2008.
[2]四川省地质矿产局.地质说明书——都江堰幅(1∶50000)[M].1996.
[3]黄勇.汶川地震中梁式桥的震害和预防震害的新方法[J].地震工程与工程震动,2008,28(5):20-26.
[4]都江堰虹口乡高原大桥基桩完整性检测报告[R].成都:中交第三公路工程局有限公司,2008.
[5]Li Xiaojun,Zhou Zhenghua,Yu Haiying,et al.Strong mo-tion observations and recordings from the great WenchuanEarthquake[J].Earthquake Engineering and EngineeringVibration,2008,7(3):235-246.
[6]叶爱君.桥梁抗震[M].北京:人民交通出版社,2002.
[7]地质剖面图[R].成都:中交第三公路工程局有限公司,2008.
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