土的非线性动剪切模量比和阻尼比不确定性分析
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摘要
利用实验资料研究了中国常规土类动剪切模量比及阻尼比随剪应变变化非线性关系的不确定性问题,包括典型应变下分布形态、概率统计指标以及不同概率水准下变化范围和规律。以中国17个省份42个城市和地区588组土样实验为基础数据,对8个典型剪应变进行的动剪切模量比及阻尼比不确定性的概率进行分析,结果表明:常规土类动剪切模量比和阻尼比的变异性以偏态分布为主,其概率统计指标呈现良好规律;各种土类动剪切模量比及阻尼比的标准差和变异系数都很大,而标准差最大值恰出现在土层地震反应计算的敏感区间内;各种土类动剪切模量比及阻尼比的外包线与其95%参考值都有较大差别,体现了实验结果显著的离散性;动剪切模量比的变异系数随剪应变而明显增大,阻尼比的变异系数随剪应变的增大而显著减小;大应变时动剪切模量比不确定性大,而小应变时阻尼比离散显著;阻尼比的变异系数要明显大于动剪切模量比的变异系数,表明阻尼比具有更大的不确定性。
By using the test data,the uncertainty of the dynamic modular ratio G/Gmax and damping ratio λ versus dynamic shear strain γ for the conventional soils in China is studied.The characteristics of the uncertainty distribution,the probability indexes as well as the range of G/Gmax and λ for the typical strains under different probabilities are presented.Based on 588 groups of test results from 42 cities and districts in 17 provinces in China,the uncertainty of the modular ratio and damping ratio versus 8 typical shear strains is analyzed.The results indicate that most of the uncertainty distribution of G/Gmax and λ is abnormal and that the statistic indexes for the probability are regular.The standard deviation and the variation coefficient of G/Gmax and λ are both significant,and meanwhile the maximum of the standard deviation just appears in the sensitive range for the seismic analysis of soil layers.The 95% reference values of G/Gmax and λ are quite different from the envelopes of G/Gmax and λ for all types of soils.The variation coefficients of G/Gmax increase with the increase of the shear strain,but the variation coefficients of λ decrease with the increase of the shear strain.The uncertainty of G/Gmax is obvious at the large strain,while that of λ is obvious at the small strain.The variation coefficients of λ are larger than those of G/Gmax,indicating the uncertainty of the dynamic damping is more remarkable than the dynamic modulus.
By using the test data,the uncertainty of the dynamic modular ratio G/Gmax and damping ratio λ versus dynamic shear strain γ for the conventional soils in China is studied.The characteristics of the uncertainty distribution,the probability indexes as well as the range of G/Gmax and λ for the typical strains under different probabilities are presented.Based on 588 groups of test results from 42 cities and districts in 17 provinces in China,the uncertainty of the modular ratio and damping ratio versus 8 typical shear strains is analyzed.The results indicate that most of the uncertainty distribution of G/Gmax and λ is abnormal and that the statistic indexes for the probability are regular.The standard deviation and the variation coefficient of G/Gmax and λ are both significant,and meanwhile the maximum of the standard deviation just appears in the sensitive range for the seismic analysis of soil layers.The 95% reference values of G/Gmax and λ are quite different from the envelopes of G/Gmax and λ for all types of soils.The variation coefficients of G/Gmax increase with the increase of the shear strain,but the variation coefficients of λ decrease with the increase of the shear strain.The uncertainty of G/Gmax is obvious at the large strain,while that of λ is obvious at the small strain.The variation coefficients of λ are larger than those of G/Gmax,indicating the uncertainty of the dynamic damping is more remarkable than the dynamic modulus.
引文
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[3]倪万魁,韩启龙.黄土土性参数的统计分析[J].工程地质学报,2001,9(1):62–67.(NI Wan-kui,HAN Qi-long.Statistical analysis of physical and mechanical indexes of the typical loess[J].Journal of Engineering Geology,2001,9(1):62–67.(in Chinese))
[4]兰青龙,贺明华,安卫平.太原地区场地土动力性能的统计分析[J].山西地震,1997(3):6–11.(LAN Qing-long,HE Ming-hua,AN Wei-ping.Several features of earthquake swarm in Taiyuan basin[J].Earthquake Research in Shan Xi,1997(3):6–11.(in Chinese))
[5]胡庆兴,刘雪珠,丛卫民,等.淮安市典型土动力特性的实验研究[J].地震工程与工程振动.2003,23(6):144–148.(HU Qing-xing,LIU Xue-zhu,CONG Wei-min,et al.Experimental study on dynamic property of typical soils for Huaian city[J].Earthquake Engineering and Engineering Vibration.2003,23(6):144–148.(in Chinese))
[6]陈国兴,刘雪珠.南京及邻近地区新近沉积土的动剪切模量和阻尼比的实验研究[J].岩石力学与工程学报,2004,23(8):1404–1411.(CHEN Guo-xing,LIU Xue-zhu.Testing study on ratio of dynamic shear moduli and ratio of damping for recently deposited soils in Nanjing and its neighboring areas[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(8):1404–1411.(in Chinese))
[7]陈国兴,刘雪珠,王炳辉.土动力参数变异性对深软场地地表地震动参数的影响[J].防灾减灾工程学报.2007,27(1):1–10.(CHEN Guo-xing,LIU Xue-zhu,WANG Bing-hui.Effect of variability of soil dynamic parameters on ground motion parameters for deep soft sites[J].Journal of Disaster Prevention and Mitigation Engineering,2007,27(1):1–10.(in Chinese))
[8]LIU Xiao-jian,SUN Rui,YUAN Xiao-ming.Requirement for error control of nonlinear experiments of soils[C]//14th World Conference on Earthquake Engineering,Beijing,2008.
[9]祝龙根,杜坚.不同类型共振柱仪对比实验[J].水电自动化与大坝监测,1990(3):26–32.(ZHU Long-gen,DU Jian.Comparison tests with different types of resonant column devices[J].Hydropower Automation and Dam Monitoring,1990(3):26–32.(in Chinese))
[10]袁晓铭,孙静.非均等固结下砂土最大动剪切模量的增长模式及Hardin公式的修正[J].岩土工程学报,2005,27(3):264–269.(YUAN Xiao-ming,SUN Jing.Model of maximum dynamic shear modulus of sand under anisotropic consolidation and revision of Hardins formula[J].Chinese Journal of Geotechnical Engineering,2005,27(3):264–269.(in Chinese))
[11]董大钧.SAS统计分析[M].沈阳:辽宁科学技术出版社,1996.(DONG Da-jun.SAS Statistical analsis[M].Shenyang:Liaoning Science and Technology Pabulishny House,1996.(in Chinese))
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