新近沉积土的动剪切模量和阻尼比试验研究
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摘要
江苏沿海地区由于特殊的地理位置优势以及经济的快速发展,港口码头、风力发电厂等重大工程不断新建。土的动剪切模量和阻尼比是重大工程进行抗震设计所必须的基础性数据。该地区的地层受晚更新世以来三次海侵的影响,普遍分布有厚度较大的海相地层。使用南京工业大学岩土工程研究所自行研制的GZZ-1型自振柱仪,结合重大工程建设,历时3年,对不区分陆、海相沉积的淤泥质土、粘土、粉质粘土、粉土、细砂等5类新近沉积土以及海相沉积的粉质粘土、粉土和细砂等3类新近沉积土共134个原状土样,进行了土的动剪切模量比和阻尼比的试验研究,结果表明:采用Martin-Davidenkov模型和陈国兴等建议的阻尼比经验公式拟合江苏沿海地区新近沉积土的动剪切模量比G/G_(max)和阻尼比λ与剪应变幅值γ_a的关系曲线是合适的,给出了各类土G/G_(max)～γ_a和λ～λ_a关系曲线经验公式的参数值;通过对比海、陆相沉积的粉质粘土、粉土和细砂等3类土的试验结果发现:海、陆相沉积的粉质粘土的动剪切模量比和阻尼比十分接近,而海、陆相沉积的粉土和细砂的动剪切模量比和阻尼比存在较大的差别。
Owing to the special geographic location and the rapid development of economy in coastal region of Jiangsu province,many important projects have been constructed such as digital strong ground motion observation sta- tions,ports or wharfs,wind power stations.The dynamic shear modulus and damping ratio of site soils are basic and necessary data for the seismic design of important projects.Based on the construction of those important projects,ex- perimental studies on dynamic shear modulus and damping ratio of 134 undisturbed soil samples are accomplished in about 3 years,using the free vibration column test system developed by Nanjing University of Technology.Those un- disturbed soil samples are muddy soils,clay,silt clay,silt and fine sand.The marine deposited soils in coastal re- gion of Jiangsu province are existed extensively due to three times of transgression after the late Pleistocene Epoch. Therefore,marine deposited silt clay,silt and fine sand are also screened.The results show that it is suitable to use Martin-Davidenkov model and the damping ratio empirical formula recommended by Chen Guoxing to fit the results of the normalized mean dynamic shear modulus ratio G/G_(max)～γ_(?) and damping ratioλ～γ_(?) curves respectively.The ref- erence values of regression coefficients are also given.By comparing the dynamic shear modulus ratio and damping ra- tio of marine deposited soils with continental deposited soils,the following results can be found:for silt clay,the dy- namic shear modulus ratio and damping ratio of marine and continental deposited soils are much dosed with each oth- er,for silt and fine sand,however,the dynamic shear modulus ratios and damping ratios of marine and continental deposited soils are obviously different.
Owing to the special geographic location and the rapid development of economy in coastal region of Jiangsu province,many important projects have been constructed such as digital strong ground motion observation sta- tions,ports or wharfs,wind power stations.The dynamic shear modulus and damping ratio of site soils are basic and necessary data for the seismic design of important projects.Based on the construction of those important projects,ex- perimental studies on dynamic shear modulus and damping ratio of 134 undisturbed soil samples are accomplished in about 3 years,using the free vibration column test system developed by Nanjing University of Technology.Those un- disturbed soil samples are muddy soils,clay,silt clay,silt and fine sand.The marine deposited soils in coastal re- gion of Jiangsu province are existed extensively due to three times of transgression after the late Pleistocene Epoch. Therefore,marine deposited silt clay,silt and fine sand are also screened.The results show that it is suitable to use Martin-Davidenkov model and the damping ratio empirical formula recommended by Chen Guoxing to fit the results of the normalized mean dynamic shear modulus ratio G/G_(max)～γ_(?) and damping ratioλ～γ_(?) curves respectively.The ref- erence values of regression coefficients are also given.By comparing the dynamic shear modulus ratio and damping ra- tio of marine deposited soils with continental deposited soils,the following results can be found:for silt clay,the dy- namic shear modulus ratio and damping ratio of marine and continental deposited soils are much dosed with each oth- er,for silt and fine sand,however,the dynamic shear modulus ratios and damping ratios of marine and continental deposited soils are obviously different.
引文
[1]赵松龄．近百年来中国东部沿海地区海面变化研究状况．中国海平面变化[M]．海洋出版社，北京．1986，15-27.(ZHAO Songling.The Researches of Sea Level Alteration in Coastal Region of Eastern China in Recent Hundred Yearn.The Sea Level Alteration of China[M]. Ocean press,Beijing.1986,15-27.(in Chinese))
[2]王强，田国．中国东部晚第四纪海侵的新构造背景[J]．地质力学学报，1999(4)：41-48．(WANG Qiang,TIAN Guo.The Neotectonic Setting of Late Qua- ternary Transgressions on The Eastern Coastal Plane of China[J].Journal of Geomechanics,1999(4):41- 48.(in Chinese))
[3]赵松龄，张宏才，苍溪树．江苏沿海平原第四纪磁性地层的研究[J]．海洋与湖沼，1987．3(2)：173- 180.(ZHAO Songling,ZHANG Hongcai,CANG Shuxi.Studies of Quaternary Magnetostratigraphy in the Coastal Region of Jiangsu [J].Oceanolngia Et Limno- logia Sinica,1987(2):173-180.(in Chinese))
[4]陈艺南，刘松玉．江苏沿海高速公路软土路基问题的工程地质分析[J]．三峡大学学报(自然科学版)，2001(6):507-511.(CHEN Yinan,LIU Songyu.En- gineering Geological Analysis of Problems of Soft-Soil Foundation for Expressway in Coastal Area of Jiangsu Province[J].Journal of China Three Gorges University. (Natural Sciences),2001(6):507-511.(in Chi- nese))
[5]邓永峰，吴燕开，刘松玉，洪振舜．连云港浅层海相软土沉积环境及物理力学性质研究[J]．工程地质学报,2005,3(1):29-33.(DE.NG Yongfeng,WU Yan- kai,LIU Songyu,HONG Zhenshun.Sediment Environ- ment of Shallow Marine Clays Deposited in Lianyungang Area and Their Physical and Mechanical Properties[J]. Journal of Engineering Geology,2005(1):29-33.(in Chinese))
[6]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.(CHEN Guoxing,ZHU Dinghua,HE Qizhi.Development and Property Test of GZZ-1 Free Vibration Column Teat System[J].Earthquake Engi- neering and Engineering Vibration,2003(1):110- 114.(in Chinese))
[7]Martin P.P.,Seed H.B.One Dimension Dynamic Ground Response Analysis[J].Journal of Geot.Eng.. ASCE,1982(7):935-952.
[8]Chen Guoxing,Liu Xuezhu.The Preliminary Study on Dynamic Characteristics of Recently Deposited Soils in Southern Area of Jiangsu Province,China[A].Pro- ceedings of the international sympesium on innovation & sustainability of structures in civil engineering-inclu- ding seismic engineering,Nov.20-22,2005,Nan- jing,China.
[2]王强，田国．中国东部晚第四纪海侵的新构造背景[J]．地质力学学报，1999(4)：41-48．(WANG Qiang,TIAN Guo.The Neotectonic Setting of Late Qua- ternary Transgressions on The Eastern Coastal Plane of China[J].Journal of Geomechanics,1999(4):41- 48.(in Chinese))
[3]赵松龄，张宏才，苍溪树．江苏沿海平原第四纪磁性地层的研究[J]．海洋与湖沼，1987．3(2)：173- 180.(ZHAO Songling,ZHANG Hongcai,CANG Shuxi.Studies of Quaternary Magnetostratigraphy in the Coastal Region of Jiangsu [J].Oceanolngia Et Limno- logia Sinica,1987(2):173-180.(in Chinese))
[4]陈艺南，刘松玉．江苏沿海高速公路软土路基问题的工程地质分析[J]．三峡大学学报(自然科学版)，2001(6):507-511.(CHEN Yinan,LIU Songyu.En- gineering Geological Analysis of Problems of Soft-Soil Foundation for Expressway in Coastal Area of Jiangsu Province[J].Journal of China Three Gorges University. (Natural Sciences),2001(6):507-511.(in Chi- nese))
[5]邓永峰，吴燕开，刘松玉，洪振舜．连云港浅层海相软土沉积环境及物理力学性质研究[J]．工程地质学报,2005,3(1):29-33.(DE.NG Yongfeng,WU Yan- kai,LIU Songyu,HONG Zhenshun.Sediment Environ- ment of Shallow Marine Clays Deposited in Lianyungang Area and Their Physical and Mechanical Properties[J]. Journal of Engineering Geology,2005(1):29-33.(in Chinese))
[6]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.(CHEN Guoxing,ZHU Dinghua,HE Qizhi.Development and Property Test of GZZ-1 Free Vibration Column Teat System[J].Earthquake Engi- neering and Engineering Vibration,2003(1):110- 114.(in Chinese))
[7]Martin P.P.,Seed H.B.One Dimension Dynamic Ground Response Analysis[J].Journal of Geot.Eng.. ASCE,1982(7):935-952.
[8]Chen Guoxing,Liu Xuezhu.The Preliminary Study on Dynamic Characteristics of Recently Deposited Soils in Southern Area of Jiangsu Province,China[A].Pro- ceedings of the international sympesium on innovation & sustainability of structures in civil engineering-inclu- ding seismic engineering,Nov.20-22,2005,Nan- jing,China.
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