一种确定导管架平台群桩p-y数据的方法
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摘要
导管架海洋平台群桩基础的桩头约束是一种弹性约束。针对具有弹性约束桩头的群桩,提出了一种利用非线性地基梁群桩模型,通过迭代计算确定导管架平台群桩p-y数据的方法。该方法首先依据单桩p-y曲线,利用具有弹性约束桩头的群桩模型,计算桩头在总荷载作用下的水平位移;再利用Poulos相互作用系数确定由于群桩相互作用引起的桩头附加水平位移,将总荷载作用下的桩头水平位移与桩头附加水平位移叠加后的结果作为迭代计算的初始桩头水平位移。然后,依据桩头荷载与初始桩头水平位移,通过对单桩p-y数据的标定,确定其修正系数Ym,进而得到与第1次计算对应的群桩p-y数据。在接下来的迭代计算中,利用每次更新后的Ym确定该次计算使用的群桩p-y数据,并据此由群桩计算模型计算桩头位移,通过对单桩p-y数据标定确定相应的Ym,直到第i次与第i-1次计算出的Ym(i)和Ym(i-1)之间相对误差小于允许误差为止。由于该方法考虑群桩效应的p-y数据,且借助具有弹性约束桩头的群桩模型进行分析,从而使计算结果能客观反映具有弹性约束桩头群桩之间的相互作用与变形特性。
The pile group head of jacket platforms is elastic constrained head.According to the elastic constrained head,a method to determine p-y data of jacket platform pile groups using the nonlinear foundation beam model of pile group is proposed.The lateral displacement of pile head is first determined using the pile group model with the elastic constrained head and p-y data of a single pile under total loads for the method.Additional lateral displacements due to pile group interactions are determined using Poulos’s interaction factors.The superposition result of above two calculations is taken as the initial lateral displacement of pile head of iterative calculations.The modified factor,Ym,of p-y data of the pile group associated with the first calculation is determined by calibrating p-y data of a single pile based on pile head loads and initial lateral displacement.For following calculations,p-y data of pile group associated with each iteration are determined using the updated Ym and then are used to determine the lateral displacement of pile group head and new Ym until the relative difference between Ym(i) and Ym(i-1) associate with the iterations i and i-1 is less than the tolerance.Because the method uses the p-y data considering pile group effects and the pile group model with the elastic constrained head to analyze the pile group interactions,results can objectively reflect interactions of jacket platform pile group and the deformation behavior of pile group with the elastic constrained head.
The pile group head of jacket platforms is elastic constrained head.According to the elastic constrained head,a method to determine p-y data of jacket platform pile groups using the nonlinear foundation beam model of pile group is proposed.The lateral displacement of pile head is first determined using the pile group model with the elastic constrained head and p-y data of a single pile under total loads for the method.Additional lateral displacements due to pile group interactions are determined using Poulos’s interaction factors.The superposition result of above two calculations is taken as the initial lateral displacement of pile head of iterative calculations.The modified factor,Ym,of p-y data of the pile group associated with the first calculation is determined by calibrating p-y data of a single pile based on pile head loads and initial lateral displacement.For following calculations,p-y data of pile group associated with each iteration are determined using the updated Ym and then are used to determine the lateral displacement of pile group head and new Ym until the relative difference between Ym(i) and Ym(i-1) associate with the iterations i and i-1 is less than the tolerance.Because the method uses the p-y data considering pile group effects and the pile group model with the elastic constrained head to analyze the pile group interactions,results can objectively reflect interactions of jacket platform pile group and the deformation behavior of pile group with the elastic constrained head.
引文
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[11]MCVAY M,CASPER R,SHANG T I.Lateral response ofthree-row groups in loose to dense sands at 3d and 5d pilespacing[J].Journal of Geotechnical Engineering,ASCE,1995,121(5):436-441.
[12]ZHANG LI-MIN,MICHAEL C M.Numerical analysis oflaterally loaded 3×3 to 7×3 pile groups in sands[J].Journal of Geotechnical and GeoenvironmentalEngineering,ASCE,1999,125(11):936-946.
[13]ILYAS T,LEUNG C F,CHOW Y K,et al.Centrifugemodel study of laterally loaded pile groups in clay[J].Journal of Geotechnical and GeoenvironmentalEngineering,ASCE,2004,130(4):264-283.
[14]CHANDRASEKARAN S S,BOOMINATHAN A,DODAGOUDAR G R.Group interaction effects onlaterally loaded piles in clay[J].Journal of Geotechnicaland Geoenvironmental Engineering,ASCE,2010,136(4):573-582.
[2]ROLLINS K M,OLSEN R J,EGBERT J J,et al.Pilespacing effects on lateral pile group behavior:Loadtests[J].Journal of Geotechnical and GeoenvironmentalEngineering,ASCE,2006,132(10):1262-1271.
[3]American Petroleum Institute.Geotechnical andFoundation Design Considerations[S].Washington,DC:API,2011.
[4]袁志林,段梦兰,陈祥余,等.水平荷载下导管架平台桩基础的非线性有限元分析[J].岩土力学,2012,33(8):2551-2560.YUAN Zhi-lin,DUAN Meng-lan,CHEN Xiang-yu,et al.Nonlinear finite element analysis of jacket platform pilefoundations under lateral loads[J].Rock and SoilMechanics,2012,33(8):2551-2560.
[5]韩理安.桩基水平承载力的群桩效率[J].岩土工程学报,1984,6(3):66-74.HAN Li-an.The group efficiency of the horizontalbearing capacity on pile foundation[J].Chinese Journalof Geotechnical Engineering,1984,6(3):66-74.
[6]韩理安.群桩水平承载力的实用计算[J].岩土工程学报,1986,8(3):27-36.HAN Li-an.Horizontal bearing capacity calculation ofpile groups[J].Chinese Journal of GeotechnicalEngineering,1986,8(3):27-36.
[7]韩理安,赵利平,韩时琳.桩侧土抗力的群桩效率[J].长沙交通学院学报,1998,14(3):74-78.HAN Li-an,ZHAO Li-ping,HAN Shi-lin.The groupefficiency of lateral earth resistance on piles[J].Journalof Changsha Communication University,1998,14(3):74-78.
[8]POULOS H G.Behavior of laterally loaded piles:Ⅱ-pilegroups[J].Journal of Soil Mechanics and FoundationsDivision,ASCE,1971,97(5):731-752.
[9]FOCHT J A,KOCH K J.Rational analysis of the lateralperformance of offshore pile group[C]//Fifth AnnualOffshore Technology Conference.Houston,Texas:[s.n.],1973.
[10]BROWN D A,MORRISON C,REESE L C.Lateralbehavior of a pile group in sand[J].Journal ofGeotechnical Engineering,ASCE,1988,114(11):1261-1276.
[11]MCVAY M,CASPER R,SHANG T I.Lateral response ofthree-row groups in loose to dense sands at 3d and 5d pilespacing[J].Journal of Geotechnical Engineering,ASCE,1995,121(5):436-441.
[12]ZHANG LI-MIN,MICHAEL C M.Numerical analysis oflaterally loaded 3×3 to 7×3 pile groups in sands[J].Journal of Geotechnical and GeoenvironmentalEngineering,ASCE,1999,125(11):936-946.
[13]ILYAS T,LEUNG C F,CHOW Y K,et al.Centrifugemodel study of laterally loaded pile groups in clay[J].Journal of Geotechnical and GeoenvironmentalEngineering,ASCE,2004,130(4):264-283.
[14]CHANDRASEKARAN S S,BOOMINATHAN A,DODAGOUDAR G R.Group interaction effects onlaterally loaded piles in clay[J].Journal of Geotechnicaland Geoenvironmental Engineering,ASCE,2010,136(4):573-582.