饱和南京细砂动剪切模量特性的大型振动台试验研究
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摘要
为了研究饱和砂土动剪切模量在振动孔隙水压力(简称孔压)升高和消散阶段的变化规律,开展了饱和南京细砂的大型振动台试验研究。基于试验数据,分析了加速度二次积分时合理选择带通滤波的低频和高频阀值的重要性,提出了由土层加速度时程确定土体动剪切模量的方法。分析孔压升高和消散阶段土体的动剪切模量比与循环周数、孔压比、剪应变幅值的关系,结果表明:与孔压升高阶段相比,孔压消散阶段的动剪切模量比明显要低,将孔压升高与消散阶段的土体动剪切模量视为相同是不合适的;大型振动台试验给出的饱和南京细砂动剪切模量比随剪应变幅值增大而衰减的速度大于室内循环三轴试验给出的结果。
In order to investigate the dynamic shear modulus of saturated sand during the increasing and dissipating stages of dynamic pore water pressure(PWP),large-scale shaking table tests on saturated Nanjing fine sand are carried out.Based on test data,the significance of reasonable choice of the threshold values of low and high frequencies with band-pass filter is analyzed to obtain the displacement from acceleration by double integration.Moreover,an approach to obtain the dynamic shear modulus from the acceleration time-history relationship is established.By analyzing the relationships among the dynamic shear modulus ratio,the cycle number of loading,the PWP ratio and the shear strain amplitudes during the increasing and dissipating stages of PWP,the following results are obtained:(1) since the dynamic shear modulus during the dissipating stage of PWP is significantly smaller than that during the increasing stage,it is unreasonable to take the dynamic shear modulus during the two stages as the same;(2) the decay rate of dynamic shear modulus with the increase of the shear strain amplitude obtained from large-scale shaking table tests for saturated Nanjing fine sand is faster than that obtained from cyclic triaxial tests,in laboratory.
In order to investigate the dynamic shear modulus of saturated sand during the increasing and dissipating stages of dynamic pore water pressure(PWP),large-scale shaking table tests on saturated Nanjing fine sand are carried out.Based on test data,the significance of reasonable choice of the threshold values of low and high frequencies with band-pass filter is analyzed to obtain the displacement from acceleration by double integration.Moreover,an approach to obtain the dynamic shear modulus from the acceleration time-history relationship is established.By analyzing the relationships among the dynamic shear modulus ratio,the cycle number of loading,the PWP ratio and the shear strain amplitudes during the increasing and dissipating stages of PWP,the following results are obtained:(1) since the dynamic shear modulus during the dissipating stage of PWP is significantly smaller than that during the increasing stage,it is unreasonable to take the dynamic shear modulus during the two stages as the same;(2) the decay rate of dynamic shear modulus with the increase of the shear strain amplitude obtained from large-scale shaking table tests for saturated Nanjing fine sand is faster than that obtained from cyclic triaxial tests,in laboratory.
引文
[1]HARDIN B O,DRNVICH V P.Shear modulus and damping insoil:measurement and parameter effects[J].Journal of theSoil Mechanics and Foundation Engineering Division,ASCE,1972,98(6):603–624.
[2]KOKUSHO T.Cyclic triaxial test of dynamic soil propertiesfor wide strain range[J].Soils and Foundations,1980,20(2):45–60.
[3]YAMADA S,HYODO M,ORENSE R P,et al.Initial shearmodulus of remolded sand-clay mixtures[J].Journal ofGeotechnical and Geoenvironmental Engineering,2008,134(7):960–971.
[4]YAMADA S,HYODO M,ORENSE R P,et al.Strain-dependent dynamic properties of remolded sand-claymixtures[J].Journal of Geotechnical and GeoenvironmentalEngineering,2008,134(7):972–981.
[5]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.(CHEN Guo-xing,LIU Xue-zhu,ZHUDing-hua,et al.Experimental studies on dynamic shearmodulus ratio and damping ratio of recently deposited soils inNanjing[J].Chinese Journal of Geoteehnieal Engineering.Chinese Journal of Geotechnical Engineering,2006,28(8):1023–1027.(in Chinese))
[6]WICHTMANN T,TRIANTAFYLLIDIS T.Influence of acyclic and dynamic loading history on dynamic properties ofdry sand,part I:Cyclic and dynamic torsional prestraining[J].Soil Dynamics and Earthquake Engineering,2004,24(2):127–147.
[7]WICHTMANN T,TRIANTAFYLLIDIS T.Influence of acyclic and dynamic loading history on dynamic properties ofdry sand,part II:Cyclic axial preloading[J].Soil Dynamicsand Earthquake Engineering,2004,24(11):789–803.
[8]MENG J.The influence of loading frequency on dynamic soilproperties[D].Georgia Institute of Technology,2003.
[9]YOSHIDA N,KOBAYASHI S,SUETOMI I,et al.Equivalentlinear method considering frequency dependent characteristicsof stiffness and damping[J].Soil Dynamics and EarthquakeEngineering.2002,22(3):205–222.
[10]ASSIMAKI D,KAUSEL E,WHITTLE A.Model fordynamic shear modulus and damping for granular soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2000,126(10):859–869.
[11]TRONCOSO J H,GARCéS E.Ageing effects in the shearmodulus of soils[J].Soil Dynamics and EarthquakeEngineering,2000,19(8):595–601.
[12]LI X S,YANG W L.Effects of vibration history on modulusand damping of dry sand[J].Journal of Geotechnical andGeoenvironmental Engineering,1998,124(11):1071–1081.
[13]何昌荣.动模量和阻尼的动三轴试验研究[J].岩土工程学报,1997,19(2):39–48.(HE Chang-rong.Dynamic triaxialtest on modulus and damping[J].Chinese Journal ofGeotechnical Engineering,1997,19(2):39–48.(inChinese))
[14]ISHIBASH I,ZHANG X J.Unified dynamic shear moduliand damping ratios of sand and clay[J].Soils andFoundations,1993,33(1):182–191.
[15]KOGA Y,MATSUO O.Shaking table tests of embankmentsresting on liquefaction sandy ground[J].Soils andFoundations,1990,30(4):162–174.
[16]ZEGHAL M,ELGAMAL A W,ZENG X,et al.Mechanismof liquefaction response in sand-silt dynamic centrifugetests[J].Soil Dynamics and Earthquake Engineering,1999,18(1):71–85.
[17]BRENNAN A J,THUSYANTHAN N I,MADABHUSHI S PG.Evaluation of shear modulus and damping in dynamiccentrifuge tests[J].Journal of Geotechnical andGeoenvironmental Engineering,2005,131(12):1488–1497.
[18]陈隽,赵冠宇,祁晓煜,等.场地土动力特性识别方法对比[J].建筑科学与工程学报,2009,26(2):32–37.(CHEN Jun,ZHAO Guan-yu,QI Xiao-yu,et al.Comparisonof soil dynamic property identification method[J].Journal ofArchitecture and Civil Engineering,2009,26(2):32–37.(inChinese))
[19]苏栋,李相崧.地震作用下自由场中饱和砂土的应力–应变推导[J].岩土力学,2010,31(1):277–282.(SU Dong,LI Xiang-song.Derivation of stress and strain of saturatedsand in free ground under seismic loading[J].Rock and SoilMechanics,2010,31(1):277–282.(in Chinese))
[20]姬美秀,陈云敏.不排水循环荷载作用过程中累积孔压对细砂弹性剪切模量Gmax的影响[J].岩土力学,2005,26(6):884–888.(JI Mei-xiu,CHEN Yun-min.Effect ofaccumulated pore pressure on shear modulus Gmax ofsaturated fine sand during undrained cyclic loading[J].Rockand Soil Mechanics,2005,26(6):884–888.(in Chinese))
[21]陈国兴,王志华,左熹,等.振动台试验叠层剪切型土箱的研制[J].岩土工程学报,2010,32(1):89–97.(CHENGuo-xing,WANG Zhi-hua,ZUO Xi,et al.Development oflaminar shear container for shaking table test[J].ChineseJournal of Geotechnical Engineering,2010,32(1):89–97.(in Chinese))
[22]HARDIN B O,DRNVICH V P.Shear modulus and dampingin soils:design equations and curves[J].Journal of the SoilMechanics and Foundation Engineering Division,ASCE,1972,98(7):667–692.
[23]HARDIN B O,BLACK W L.Closure on vibration modulusof normally consolidated clay[J].Journal of Soil Mechanics&Foundations Div,ASCE,1969,95(SM6):1531–1537.
[24]HARDIN B O,BLACK W L.Vibration modulus of normallyconsolidated clay[J].Journal of Soil Mechanics&Foundations Div,ASCE,1968,94(2):353–369.
[25]王炳辉,陈国兴,胡庆兴.南京细砂动剪切模量和阻尼比的试验研究[J].世界地震工程,2010,26(3):7–15.(WANG Bing-hui,CHEN Guo-xing,HU Qing-xing.Experimental research on dynamic shear modulus anddamping of Nanjing fine sand[J].World EarthquakeEngineering,2010,26(3):7–15.(in Chinese))
[2]KOKUSHO T.Cyclic triaxial test of dynamic soil propertiesfor wide strain range[J].Soils and Foundations,1980,20(2):45–60.
[3]YAMADA S,HYODO M,ORENSE R P,et al.Initial shearmodulus of remolded sand-clay mixtures[J].Journal ofGeotechnical and Geoenvironmental Engineering,2008,134(7):960–971.
[4]YAMADA S,HYODO M,ORENSE R P,et al.Strain-dependent dynamic properties of remolded sand-claymixtures[J].Journal of Geotechnical and GeoenvironmentalEngineering,2008,134(7):972–981.
[5]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.(CHEN Guo-xing,LIU Xue-zhu,ZHUDing-hua,et al.Experimental studies on dynamic shearmodulus ratio and damping ratio of recently deposited soils inNanjing[J].Chinese Journal of Geoteehnieal Engineering.Chinese Journal of Geotechnical Engineering,2006,28(8):1023–1027.(in Chinese))
[6]WICHTMANN T,TRIANTAFYLLIDIS T.Influence of acyclic and dynamic loading history on dynamic properties ofdry sand,part I:Cyclic and dynamic torsional prestraining[J].Soil Dynamics and Earthquake Engineering,2004,24(2):127–147.
[7]WICHTMANN T,TRIANTAFYLLIDIS T.Influence of acyclic and dynamic loading history on dynamic properties ofdry sand,part II:Cyclic axial preloading[J].Soil Dynamicsand Earthquake Engineering,2004,24(11):789–803.
[8]MENG J.The influence of loading frequency on dynamic soilproperties[D].Georgia Institute of Technology,2003.
[9]YOSHIDA N,KOBAYASHI S,SUETOMI I,et al.Equivalentlinear method considering frequency dependent characteristicsof stiffness and damping[J].Soil Dynamics and EarthquakeEngineering.2002,22(3):205–222.
[10]ASSIMAKI D,KAUSEL E,WHITTLE A.Model fordynamic shear modulus and damping for granular soils[J].Journal of Geotechnical and Geoenvironmental Engineering,2000,126(10):859–869.
[11]TRONCOSO J H,GARCéS E.Ageing effects in the shearmodulus of soils[J].Soil Dynamics and EarthquakeEngineering,2000,19(8):595–601.
[12]LI X S,YANG W L.Effects of vibration history on modulusand damping of dry sand[J].Journal of Geotechnical andGeoenvironmental Engineering,1998,124(11):1071–1081.
[13]何昌荣.动模量和阻尼的动三轴试验研究[J].岩土工程学报,1997,19(2):39–48.(HE Chang-rong.Dynamic triaxialtest on modulus and damping[J].Chinese Journal ofGeotechnical Engineering,1997,19(2):39–48.(inChinese))
[14]ISHIBASH I,ZHANG X J.Unified dynamic shear moduliand damping ratios of sand and clay[J].Soils andFoundations,1993,33(1):182–191.
[15]KOGA Y,MATSUO O.Shaking table tests of embankmentsresting on liquefaction sandy ground[J].Soils andFoundations,1990,30(4):162–174.
[16]ZEGHAL M,ELGAMAL A W,ZENG X,et al.Mechanismof liquefaction response in sand-silt dynamic centrifugetests[J].Soil Dynamics and Earthquake Engineering,1999,18(1):71–85.
[17]BRENNAN A J,THUSYANTHAN N I,MADABHUSHI S PG.Evaluation of shear modulus and damping in dynamiccentrifuge tests[J].Journal of Geotechnical andGeoenvironmental Engineering,2005,131(12):1488–1497.
[18]陈隽,赵冠宇,祁晓煜,等.场地土动力特性识别方法对比[J].建筑科学与工程学报,2009,26(2):32–37.(CHEN Jun,ZHAO Guan-yu,QI Xiao-yu,et al.Comparisonof soil dynamic property identification method[J].Journal ofArchitecture and Civil Engineering,2009,26(2):32–37.(inChinese))
[19]苏栋,李相崧.地震作用下自由场中饱和砂土的应力–应变推导[J].岩土力学,2010,31(1):277–282.(SU Dong,LI Xiang-song.Derivation of stress and strain of saturatedsand in free ground under seismic loading[J].Rock and SoilMechanics,2010,31(1):277–282.(in Chinese))
[20]姬美秀,陈云敏.不排水循环荷载作用过程中累积孔压对细砂弹性剪切模量Gmax的影响[J].岩土力学,2005,26(6):884–888.(JI Mei-xiu,CHEN Yun-min.Effect ofaccumulated pore pressure on shear modulus Gmax ofsaturated fine sand during undrained cyclic loading[J].Rockand Soil Mechanics,2005,26(6):884–888.(in Chinese))
[21]陈国兴,王志华,左熹,等.振动台试验叠层剪切型土箱的研制[J].岩土工程学报,2010,32(1):89–97.(CHENGuo-xing,WANG Zhi-hua,ZUO Xi,et al.Development oflaminar shear container for shaking table test[J].ChineseJournal of Geotechnical Engineering,2010,32(1):89–97.(in Chinese))
[22]HARDIN B O,DRNVICH V P.Shear modulus and dampingin soils:design equations and curves[J].Journal of the SoilMechanics and Foundation Engineering Division,ASCE,1972,98(7):667–692.
[23]HARDIN B O,BLACK W L.Closure on vibration modulusof normally consolidated clay[J].Journal of Soil Mechanics&Foundations Div,ASCE,1969,95(SM6):1531–1537.
[24]HARDIN B O,BLACK W L.Vibration modulus of normallyconsolidated clay[J].Journal of Soil Mechanics&Foundations Div,ASCE,1968,94(2):353–369.
[25]王炳辉,陈国兴,胡庆兴.南京细砂动剪切模量和阻尼比的试验研究[J].世界地震工程,2010,26(3):7–15.(WANG Bing-hui,CHEN Guo-xing,HU Qing-xing.Experimental research on dynamic shear modulus anddamping of Nanjing fine sand[J].World EarthquakeEngineering,2010,26(3):7–15.(in Chinese))
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