基于侧阻硬化与软化模型的大直径桩基水平承载力研究
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摘要
从桩侧竖向摩阻力作为大直径基桩水平承载力显著影响因素的角度出发,首先分别建立了桩侧摩阻力硬化和软化τ–s模型作用下单位长度桩身抗力矩Ms的数值解及其相应的解析方程。随后,在传递矩阵法基础上分别推导了考虑桩身抗力矩Ms影响的传递矩阵系数解析解。最后,通过影响参数及工程案例对比分析,分别证明了本文所推导的附加弯矩–转角本构模型和传递矩阵解的正确性,并得出以下结论:对侧阻硬化模型而言,桩身抗力矩Ms随着桩径d、抗剪刚度系数比值k2/k1的增加以及弹性极限位移seu的减小而增加;对侧阻软化模型而言,桩身抗力矩Ms随着桩径d、参数β(=su2/seu)和αres(=τu,res/τu,eq)的增加而增加。
From the perspective of the vertical shaft resistance producing significant contribution to the lateral bearing capacity of large-diameter pile foundation, the numerical and analytical solutions are firstly established for pile shaft resisting moment per unit length Ms induced by hardening and softening τ-s curve models of pile side friction, respectively. Furthermore, the analytical solutions for transfer matrix coefficients with consideration of the influences of shaft resisting moment are also obtained on the basis of the transfer matrix method. Finally, comparative analysis of influence factors and project case are performed, and the comparistive results verify the correctness of the proposed constitutive models for shaft resisting moment and transfer matrix solution. Moreover, for the hardening model for shaft resistance, the shaft resisting moment Ms increases with the increasing pile diameter d, ratio of shear stiffness coefficients k2/k1 and decreasing elastic limit displacement seu. Meanwhile, for the softening model for shaft resistance, the shaft resisting moment Ms increases with the increase of pile diameter d, parameters β(=su2/seu) and αres(=τu,res/τu,eq).
From the perspective of the vertical shaft resistance producing significant contribution to the lateral bearing capacity of large-diameter pile foundation, the numerical and analytical solutions are firstly established for pile shaft resisting moment per unit length Ms induced by hardening and softening τ-s curve models of pile side friction, respectively. Furthermore, the analytical solutions for transfer matrix coefficients with consideration of the influences of shaft resisting moment are also obtained on the basis of the transfer matrix method. Finally, comparative analysis of influence factors and project case are performed, and the comparistive results verify the correctness of the proposed constitutive models for shaft resisting moment and transfer matrix solution. Moreover, for the hardening model for shaft resistance, the shaft resisting moment Ms increases with the increasing pile diameter d, ratio of shear stiffness coefficients k2/k1 and decreasing elastic limit displacement seu. Meanwhile, for the softening model for shaft resistance, the shaft resisting moment Ms increases with the increase of pile diameter d, parameters β(=su2/seu) and αres(=τu,res/τu,eq).
引文
[1]ASHOUR M,HELAL A.Contribution of vertical skin friction to the lateral resistance of large-diameter shafts[J].Journal of Bridge Engineering,2014,19(2):289-302.
[2]BYRNE BW,MCADAM R,BURD H,et al.New design methods for large diameter piles under lateral loading for offshore wind applications[J].Front Offshore Geotech III,2010,60:705-714.
[3]LAM I P,MARTIN G R.Seismic design of highway bridge foundations[R].Springfield:Federal Highway Administration,1986.
[4]MCVAY M C,NIRAULA L.Development of p-y curves for large diameter piles/drilled shafts in limestone for FBPIER[R].Florida:University of Florida,2004.
[5]ASSIMAKI D,GAZETAS G.A simplified model for lateral response of large diameter caisson foundations:linear elastic formulation[J].Soil Dynamics and Earthquake Engineering,2009,29(2):268-291.
[6]GEROLYMOS N,GAZETAS G.Winkler model for lateral response of rigid caisson foundations in linear soil[J].Soil Dynamics and Earthquake Engineering,2006,26(5):347-361.
[7]陈龙珠,梁国钱,朱金颖,等.桩轴向荷载-沉降曲线的一种解析算法[J].岩土工程学报,1994,16(6):30-38.(CHEN Long-zhu,LIANG Guo-qian,ZHU Jin-ying,et al.Analysis calculation of axial loading-settlement curve of piles[J].Chinese Journal of Geotechnical Engineering,1994,16(6):30-38.(in Chinese))
[8]肖宏彬.竖向荷载作用下大直径桩的荷载传递理论及应用研究[D].长沙:中南大学,2005.(XIAO Hong-bin.Theoretical and application research on load transfer of vertically loading large diameter piles[D].Changsha:Central South University,2005.(in Chinese))
[9]BHUSHAN K,FONG P T,HALEY S C.Lateral load tests on drilled piers in stiff clays[J].Journal of the Geotechnical Engineering Division,1979,105(8):969-985.
[10]API.Recommended practice for planning,designing and constructing fixed offshore platforms-working stress design[S].API Recommended Practice 2A-WSD(RP2AWSD).21st Ed.Washington,DC,2000.
[11]竺明星.组合荷载作用下被动桩承载机理研究[D].南京:东南大学,2016.(ZHU Ming-xing.Research on bearing mechanism of passive pile under combined loads[D].Nanjing:Southeast University,2016.(in Chinese))
[2]BYRNE BW,MCADAM R,BURD H,et al.New design methods for large diameter piles under lateral loading for offshore wind applications[J].Front Offshore Geotech III,2010,60:705-714.
[3]LAM I P,MARTIN G R.Seismic design of highway bridge foundations[R].Springfield:Federal Highway Administration,1986.
[4]MCVAY M C,NIRAULA L.Development of p-y curves for large diameter piles/drilled shafts in limestone for FBPIER[R].Florida:University of Florida,2004.
[5]ASSIMAKI D,GAZETAS G.A simplified model for lateral response of large diameter caisson foundations:linear elastic formulation[J].Soil Dynamics and Earthquake Engineering,2009,29(2):268-291.
[6]GEROLYMOS N,GAZETAS G.Winkler model for lateral response of rigid caisson foundations in linear soil[J].Soil Dynamics and Earthquake Engineering,2006,26(5):347-361.
[7]陈龙珠,梁国钱,朱金颖,等.桩轴向荷载-沉降曲线的一种解析算法[J].岩土工程学报,1994,16(6):30-38.(CHEN Long-zhu,LIANG Guo-qian,ZHU Jin-ying,et al.Analysis calculation of axial loading-settlement curve of piles[J].Chinese Journal of Geotechnical Engineering,1994,16(6):30-38.(in Chinese))
[8]肖宏彬.竖向荷载作用下大直径桩的荷载传递理论及应用研究[D].长沙:中南大学,2005.(XIAO Hong-bin.Theoretical and application research on load transfer of vertically loading large diameter piles[D].Changsha:Central South University,2005.(in Chinese))
[9]BHUSHAN K,FONG P T,HALEY S C.Lateral load tests on drilled piers in stiff clays[J].Journal of the Geotechnical Engineering Division,1979,105(8):969-985.
[10]API.Recommended practice for planning,designing and constructing fixed offshore platforms-working stress design[S].API Recommended Practice 2A-WSD(RP2AWSD).21st Ed.Washington,DC,2000.
[11]竺明星.组合荷载作用下被动桩承载机理研究[D].南京:东南大学,2016.(ZHU Ming-xing.Research on bearing mechanism of passive pile under combined loads[D].Nanjing:Southeast University,2016.(in Chinese))