宁波近海沉积土动力特性的试验研究
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摘要
土的动模量、阻尼比和砂土抗液化强度是土动力特性的主要指标,是研究重大工程场地设计地震动参数的基础性资料。结合宁波象山港大桥工程场地地震安全性评价工作,采用南京工业大学自行研制的GZZ-1型自振柱仪,首次对宁波近海沉积的淤泥质粘性土、粘性土和砂土进行了动模量和阻尼比的试验研究。发现土的动剪切模量比G/Gmax、阻尼比λ与剪应变幅值γ的关系,可分别采用Martin-Davidenkov模型和作者建议的阻尼比经验公式进行拟合;此外,采用南京工业大学自行研制的DSZ-1型动三轴仪,首次对宁波近海沉积的砂土和粉土进行了液化试验研究,结果表明,宁波近海沉积的砂土和粉土的抗液化强度可采用指数函数进行拟合,且与南京长江三桥场地粉土的抗液化强度相近,但明显大于福建标准砂的抗液化强度。
The dynamic shear modulus and damping ratio of soils are two principle indexes of soil dynamic characteristics,and are still the basic data of design ground motion parameter research for important project's site.In this paper,combining with the work of earthquake safety assessment of Xiangshan Port Bridge's site in Ningbo City,using the free vibration column test system developed by Nanjing University of Technology,the dynamic modulus and damping ratio tests for Ningbo's offshore sediment muddy clay,clay and sand soils are conducted for the first time.The results show that it is suitable to use Martin-Davidenkov model and the empirical damping ratio formula recommended by Chen Guo-xing to fit the relationship of the mean dynamic shear modulus ratio G/G_max and damping ratio λ to amplitude of shear strain γ.In addition,using the cyclic triaxial test system developed by Nanjing University of Technology,the liquefaction tests of Ningbo's offshore sediment sand and silt soils are also conducted for the first time.And the result shows that the liquefaction resistance of Ningbo's offshore sediment sand and silt soils can be expressed by the empirical exponential function formula.Compared with the liquefaction resistance of the sand and silt at Nanjing's Third Bridge of Yangtse River and Fujian standard sand,the liquefaction resistance of Ningbo's offshore sediment sand and silt is closed to that of the silt at Nanjing's Third Bridge of Yangtse River,and it is obviously larger than that of Fujian standard sand.
The dynamic shear modulus and damping ratio of soils are two principle indexes of soil dynamic characteristics,and are still the basic data of design ground motion parameter research for important project's site.In this paper,combining with the work of earthquake safety assessment of Xiangshan Port Bridge's site in Ningbo City,using the free vibration column test system developed by Nanjing University of Technology,the dynamic modulus and damping ratio tests for Ningbo's offshore sediment muddy clay,clay and sand soils are conducted for the first time.The results show that it is suitable to use Martin-Davidenkov model and the empirical damping ratio formula recommended by Chen Guo-xing to fit the relationship of the mean dynamic shear modulus ratio G/G_max and damping ratio λ to amplitude of shear strain γ.In addition,using the cyclic triaxial test system developed by Nanjing University of Technology,the liquefaction tests of Ningbo's offshore sediment sand and silt soils are also conducted for the first time.And the result shows that the liquefaction resistance of Ningbo's offshore sediment sand and silt soils can be expressed by the empirical exponential function formula.Compared with the liquefaction resistance of the sand and silt at Nanjing's Third Bridge of Yangtse River and Fujian standard sand,the liquefaction resistance of Ningbo's offshore sediment sand and silt is closed to that of the silt at Nanjing's Third Bridge of Yangtse River,and it is obviously larger than that of Fujian standard sand.
引文
[1]孙静,袁晓铭.土的动模量和阻尼比研究述评[J].世界地震工程2003,19(1):262-264
[2]祝龙根,吴晓峰.低幅剪应变条件下砂土的动力特性的研究[J].大坝观测与土工测试,1988,12(1):27-33.
[3]谢君斐,石兆吉.原状饱和粘土动力性能的试验研究[R].哈尔滨:中国地震局工程力学研究所,1973.
[4]童华炜,朱博鸿.增湿对黄土动剪切模量及阻尼比的影响[C]//第三届全国土动力学学术会议.上海:同济大学出版社,1990:117-120.
[5]费涵昌,吴一伟.黄浦江大桥桥址土层的动力特性研究[C]//第三届全国土动力学学术会议.上海:同济大学出版社,1990:303-308.
[6]阮元成.坝体原状土的动剪切模量[C]//第三届全国土动力学学术会议.上海:同济大学出版社,1990:165-168.
[7]陈国兴,刘雪珠,朱定华,等.南京新近沉积土动剪切模量比与阻尼比的试验研究[J].岩土工程学报,2006,28(8):1023-1027.
[8]Chen Guo-xing,Zhu Ding-hua.Astudy on dynamic shear modulus ratio and damping ratio of recently deposited soils for southern region of Jiang-su province along Yangtze river,China[C]//Proceeding fourth International Conference on Soft Soil Engineering,Vancouver,Canada,London:Taylor and Francis Group,2006.
[9]Jianfeng Z,Ronald D A,Juang C H.Normalized shear modulus and material damping ratio relationships[J].Journal of Geotechnical and Geoen-vironmental Engineering,ASCE.2005:453-464.
[10]吕悦军,唐荣余,沙海军.海底土类动剪切模量比和阻尼比试验研究[J].防灾减灾工程学报,2003,23(2);35-42.
[11]陈国兴,朱定华,何启智.GZZ-1型自振柱试验机研制与性能试验[J].地震工程与工程振动,2003,23(1):110-114.
[12]陈国兴,朱定华,何启智.DSZ-1型动三轴试验机研制与性能试验[J].2002,22(6):71-74.
[13]陈国兴.岩土地震工程学[M].北京:科学出版社,2007.
[2]祝龙根,吴晓峰.低幅剪应变条件下砂土的动力特性的研究[J].大坝观测与土工测试,1988,12(1):27-33.
[3]谢君斐,石兆吉.原状饱和粘土动力性能的试验研究[R].哈尔滨:中国地震局工程力学研究所,1973.
[4]童华炜,朱博鸿.增湿对黄土动剪切模量及阻尼比的影响[C]//第三届全国土动力学学术会议.上海:同济大学出版社,1990:117-120.
[5]费涵昌,吴一伟.黄浦江大桥桥址土层的动力特性研究[C]//第三届全国土动力学学术会议.上海:同济大学出版社,1990:303-308.
[6]阮元成.坝体原状土的动剪切模量[C]//第三届全国土动力学学术会议.上海:同济大学出版社,1990:165-168.
[7]陈国兴,刘雪珠,朱定华,等.南京新近沉积土动剪切模量比与阻尼比的试验研究[J].岩土工程学报,2006,28(8):1023-1027.
[8]Chen Guo-xing,Zhu Ding-hua.Astudy on dynamic shear modulus ratio and damping ratio of recently deposited soils for southern region of Jiang-su province along Yangtze river,China[C]//Proceeding fourth International Conference on Soft Soil Engineering,Vancouver,Canada,London:Taylor and Francis Group,2006.
[9]Jianfeng Z,Ronald D A,Juang C H.Normalized shear modulus and material damping ratio relationships[J].Journal of Geotechnical and Geoen-vironmental Engineering,ASCE.2005:453-464.
[10]吕悦军,唐荣余,沙海军.海底土类动剪切模量比和阻尼比试验研究[J].防灾减灾工程学报,2003,23(2);35-42.
[11]陈国兴,朱定华,何启智.GZZ-1型自振柱试验机研制与性能试验[J].地震工程与工程振动,2003,23(1):110-114.
[12]陈国兴,朱定华,何启智.DSZ-1型动三轴试验机研制与性能试验[J].2002,22(6):71-74.
[13]陈国兴.岩土地震工程学[M].北京:科学出版社,2007.
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