竖向激励场下考虑桩土滑移的单桩动力性态
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摘要
较大竖向地震激励下,桩土间有可能发生桩土相对滑移。为了考虑这种强震条件下桩土动力响应性态,提出了考虑该桩土滑移的桩土界面力的传递模型,并建立动力微分方程进行求解,得到桩基动力响应的位移显式表达式。定义了桩基动力响应系数,得到无限桩长、纯摩擦桩和端承桩等几种情况下的桩基动力响应系数的表达式。数值计算结果表明:考虑桩土滑移的桩基动力响应与不考虑桩土滑移的计算结果差距较大,尤其是在桩土模量比较大的情况下,差距更大;考虑桩土滑移的计算结果在低频段就不接近1,且出现振荡的临界频率点较低。因此,更为精细的桩土动力接触机理的研究尤其是试验研究十分必要。
There would be relative slip between pile and soil under strong vertical earthquake excitation.A force transfer model considering the slip between pile and soil was presented.A dynamic differential equation was established and solved to obtain the explicit displacement response of the pile.A kinematic response coefficient of the pile was defined,and formulations of the kinematic response coefficient for infinitely-long piles,completely free-toe piles and end-bearing piles were obtained.Numerical results showed great difference if slip between pile and soil is considered,especially when ratio of pile modulus to soil modulus is large.The kinematic response coefficient of the pile is not close to one even if the frequency is low and the critical frequency of beginning oscillation is less if slip between pile and soil is considered.So more careful study especially experiment study on the contact mechanism between pile and soil is necessary.
There would be relative slip between pile and soil under strong vertical earthquake excitation.A force transfer model considering the slip between pile and soil was presented.A dynamic differential equation was established and solved to obtain the explicit displacement response of the pile.A kinematic response coefficient of the pile was defined,and formulations of the kinematic response coefficient for infinitely-long piles,completely free-toe piles and end-bearing piles were obtained.Numerical results showed great difference if slip between pile and soil is considered,especially when ratio of pile modulus to soil modulus is large.The kinematic response coefficient of the pile is not close to one even if the frequency is low and the critical frequency of beginning oscillation is less if slip between pile and soil is considered.So more careful study especially experiment study on the contact mechanism between pile and soil is necessary.
引文
[1]Aki K,Richards P.Quantitative seismology[M].NewYork:Pergamon,1980
[2]Papazoglou A J,Elnashai A S.Analytical and field evidenceof the damaging effect of vertical earthquake ground motion[J].Earthquake Engineering&Structural Dynamics,1996,25(10):1109-1137
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[6]阙仁波,王奎华.考虑土体三维波动效应时黏性阻尼土中桩的纵向振动特性及其应用研究[J].岩石力学与工程学报,2007,26(2):381-390(Que Renbo,WangKuihua.Theory on long gitudinal vibration of pile in viscousdamping soil layer considering three-dimensional waveeffect and its applications[J].Chinese Journal of RockMechanics and Engineering,2007,26(2):381-390(inChinese))
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[8]Tham L G,Chu C K,Lei Z X.Analysis of the transientresponse of vertically loaded single piles by time-domainBEM[J].Computers and Geotechnics,1996,19(2):117-136
[9]Novak M.Soil-pile interaction[C]∥Proceedings of6th WorldConference on Earthquake Engineering.New Delhi:1977,4:97-102
[10]Mylonakis G,Gazetas G.Kinematic pile response to verticalP-wave seismic excitation[J].Journal of Geotechnical andgeoenvironmental Engineering,2002,10:860-867
[11]Novak M,Sheta M.Approximate approach to contact effectof piles in dynamic response of pile[C]∥Proceedings ofGeotechnical Engineering Division,ASCE NationalConvention.Florida,1980:53-79
[12]栾茂田,孔德森,杨庆,等.层状土中单桩竖向简谐动力响应的简化解析方法[J].岩土力学,2005,26(3):375-380(Luan Maotian,Kong Desen,Yang Qing,et al.Simplified analytic method of vertical harmonic response ofsingle pile embedded in layered soils[J].Rock and SoilMechanics,2005,26(3):375-380(in Chinese))
[13]Naggar E I,Novak M.Nonlinear model for dynamic axialpile response[J].Journal of Geotechnical Engineering,ASCE,1994,120(2):308-329
[14]Kondner R L.Hyperbolic stress strain response:cohesivesoils[J].Journal of the Soil Mechanics and FoundationEngineering Division,ASCE,1963:89-96
[15]Kobayashi K,Yao S,Yoshida N.Dynamic compliance ofpile grou Pconsidering nonlinear behavior around piles[C]∥Proceedings of 2nd International Conference on RecentAdvances in Geotechnical Earthquake Engineering and SoilDynamics.St.Louis,Missouri,1991:785-792
[16]Gazetas G,Fan K,Tazoh T,et al.Seismic response ofsoil-pile-foundation-structure systems:some recentdevelopments[J].Piles Under Dynamic Loads,Geotech.Special Publ.,ASCE,1992,(34):56-93
[2]Papazoglou A J,Elnashai A S.Analytical and field evidenceof the damaging effect of vertical earthquake ground motion[J].Earthquake Engineering&Structural Dynamics,1996,25(10):1109-1137
[3]Han Y C.Dynamic vertical response of piles in nonlinear soil[J].Journal of Geotechnical and GeoenvironmentalEngineering,1997,8:710-716
[4]Novak M.Dynamic stiffness and damping of piles[J].CanadianGeotechnical Journal,1974,11:574-598
[5]Novak M.Vertical vibration of floating piles[J].Journal ofEngineering Mechanics Division,ASCE,1977,103:153-168
[6]阙仁波,王奎华.考虑土体三维波动效应时黏性阻尼土中桩的纵向振动特性及其应用研究[J].岩石力学与工程学报,2007,26(2):381-390(Que Renbo,WangKuihua.Theory on long gitudinal vibration of pile in viscousdamping soil layer considering three-dimensional waveeffect and its applications[J].Chinese Journal of RockMechanics and Engineering,2007,26(2):381-390(inChinese))
[7]Cairo R,Conte E,Dente G.Analysis of pile groups undervertical harmonic vibration[J].Computers andGeotechnics,2005,32:545-554
[8]Tham L G,Chu C K,Lei Z X.Analysis of the transientresponse of vertically loaded single piles by time-domainBEM[J].Computers and Geotechnics,1996,19(2):117-136
[9]Novak M.Soil-pile interaction[C]∥Proceedings of6th WorldConference on Earthquake Engineering.New Delhi:1977,4:97-102
[10]Mylonakis G,Gazetas G.Kinematic pile response to verticalP-wave seismic excitation[J].Journal of Geotechnical andgeoenvironmental Engineering,2002,10:860-867
[11]Novak M,Sheta M.Approximate approach to contact effectof piles in dynamic response of pile[C]∥Proceedings ofGeotechnical Engineering Division,ASCE NationalConvention.Florida,1980:53-79
[12]栾茂田,孔德森,杨庆,等.层状土中单桩竖向简谐动力响应的简化解析方法[J].岩土力学,2005,26(3):375-380(Luan Maotian,Kong Desen,Yang Qing,et al.Simplified analytic method of vertical harmonic response ofsingle pile embedded in layered soils[J].Rock and SoilMechanics,2005,26(3):375-380(in Chinese))
[13]Naggar E I,Novak M.Nonlinear model for dynamic axialpile response[J].Journal of Geotechnical Engineering,ASCE,1994,120(2):308-329
[14]Kondner R L.Hyperbolic stress strain response:cohesivesoils[J].Journal of the Soil Mechanics and FoundationEngineering Division,ASCE,1963:89-96
[15]Kobayashi K,Yao S,Yoshida N.Dynamic compliance ofpile grou Pconsidering nonlinear behavior around piles[C]∥Proceedings of 2nd International Conference on RecentAdvances in Geotechnical Earthquake Engineering and SoilDynamics.St.Louis,Missouri,1991:785-792
[16]Gazetas G,Fan K,Tazoh T,et al.Seismic response ofsoil-pile-foundation-structure systems:some recentdevelopments[J].Piles Under Dynamic Loads,Geotech.Special Publ.,ASCE,1992,(34):56-93
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