黏土中海底管线竖向贯入阻力研究
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摘要
深水海底管线的底部稳定性受管线的竖向贯入深度和阻力影响。采用耦合欧拉-拉格朗日法(CEL)模拟黏土中海底管线竖向大变形贯入过程,并通过子程序VUSDFLD研究土体的应变率效应和应变软化对管线承载力的影响;分析了贯入过程中管线两侧隆起土体提供的阻力,并对其进行了敏感性分析,提出了表面隆起承载力系数的公式。研究结果表明,管线承载力系数随土体应变率的增大而显著增加;土体灵敏度越大,土体软化速率越快,管线的承载力系数越低。表面隆起承载力系数取决于土体的有效重度,并且贯入深度越大,土体的有效重度对表面隆起承载力的影响越明显。通过拟合数值结果,得到了表面隆起承载力表达式。
The on-bottom stability of deepwater seabed pipelines is affected by the vertical penetration depth and resistance. In this study, the coupled Eulerian-Lagrangian approach(CEL) was used to simulate the vertical penetration of pipelines in cohesive soil,and the effects of strain rate behavior and strain softening on bearing capacity of pipelines were studied by subprogram VUSDFLD.The resistance provided by the heaved-soil on both sides of the pipeline during the penetration process was analyzed and the sensitivity analysis of the resistance was implemented, then a surface heave capacity factor was proposed. Results indicated that bearing capacity factor of the pipeline increases significantly with the increase of strain rate parameter. A high sensitivity of soil leads to a fast softening rate of soil and a low bearing capacity factor of pipeline. The surface heave capacity factor mainly depends on the submerged weight of the soil. Moreover, the greater the penetration depth, the more obvious the effect of the submerged weight of soil on the bearing capacity of surface heave. An expression describring the surface heave capacity is developed by fitting the numerical results.
The on-bottom stability of deepwater seabed pipelines is affected by the vertical penetration depth and resistance. In this study, the coupled Eulerian-Lagrangian approach(CEL) was used to simulate the vertical penetration of pipelines in cohesive soil,and the effects of strain rate behavior and strain softening on bearing capacity of pipelines were studied by subprogram VUSDFLD.The resistance provided by the heaved-soil on both sides of the pipeline during the penetration process was analyzed and the sensitivity analysis of the resistance was implemented, then a surface heave capacity factor was proposed. Results indicated that bearing capacity factor of the pipeline increases significantly with the increase of strain rate parameter. A high sensitivity of soil leads to a fast softening rate of soil and a low bearing capacity factor of pipeline. The surface heave capacity factor mainly depends on the submerged weight of the soil. Moreover, the greater the penetration depth, the more obvious the effect of the submerged weight of soil on the bearing capacity of surface heave. An expression describring the surface heave capacity is developed by fitting the numerical results.
引文
[1]唐丕鑫,杨树耕,宋艾恒,等.海底裸置与埋置管线自沉过程对比研究[J].海洋工程,2015,33(2):89-96.TANG Pi-xin,YANG Shu-gen,SONG Ai-heng,et al.Comparative study of the bare and buried submarine pipeline sinkings[J].China Ocean Engineering,2015,33(2):89-96.
[2]WESTGATE Z J,RANDOLPH M F,WHITE D J,et al.The influence of sea state on as-laid pipeline embedment:a case study[J].Applied Ocean Research,2010,32(3):321-331.
[3]LIM S J.An experimental investigation of pipeline stability in very soft clay[D].Houston:University of Houston,1974.
[4]RANDOLPH M F,HOULSBY G T.The limiting pressure on a circular pile loaded laterally in cohesive soil[J].Géotechnique,1984,36(3):457-457.
[5]MURFF J D,WAGNER D A,RANDOLPH M F.Pipe penetration in cohesive soil[J].Géotechnique,1989,39(2):213-229.
[6]DINGLE H RC,WHITE D J W J,GAUDIN C G.Mechanisms of pipe embedment and lateral breakout on soft clay[J].Canadian Geotechnical Journal,2008,45(5):636-652.
[7]AUBENY C P,SHI H,MURFF J D.Collapse loads for a cylinder embedded in trench in cohesive soil[J].International Journal of Geomechanics,2005,5(4):320-325.
[8]WANG D,WHITE D J,RANDOLPH M F.Large-deformation finite element analysis of pipe penetration and large-amplitude lateral displacement[J].Canadian Geotechnical Journal,2010,47(8):842-856.
[9]CHATTERJEE S,RANDOLPH M F,WHITE D J.The effects of penetration rate and strain softening on the vertical penetration resistance of seabed pipelines[J].Géotechnique,2012,62(7):573-582.
[10]DUTTA S,HAWLADER B,PHILLIPS R.Finite element modeling of partially embedded pipelines in clay seabed using coupled Eulerian-Lagrangian method[J].Canadian Geotechnical Journal,2015,52(1):58-72.
[11]MERIFIELD R S,WHITE D J,RANDOLPH M F.Effect of surface heave on response of partially embedded pipelines on clay[J].Journal of Geotechnical&Geoenvironmental Engineering,2009,135(6):819-829.
[12]CATHIE D N,JAECK C,BALLARD J C,et al.Pipeline geotechnics-state-of-the-art[C]//International Symposium on the Frontiers in Offshore Geotechnics.Perth:Taylor and Francis,2005:95-114.
[13]SENTHILKUMAR M,RAJEEV P,ROBERT D J,et al.Undrained load-displacement behavior of partially embedded pipeline on seabed[J].Journal of Pipeline Systems Engineering and Practice,2015,7(1):04015016.
[14]Abaqus(2010).Standard user’s manual,Abaqus 6.10[M].Providence,RI,USA:Dassault Syste`mes Simulia Corp,2010.
[15]闫澍旺,林澍,霍知亮,等.桶形基础液压下沉过程的耦合欧拉-拉格朗日有限元法分析[J].岩土力学,2017,38(1):247-252.YAN Shu-wang,LIN Shu,HUO Zhi-liang,et al.Coupled Eulerian-Lagrangian finite element analysis of suction caisson penetration processes under hydraulic pressure[J].Rock and Soil Mechanics,2017,38(1):247-252.
[16]THO K K,LEUNG C F,CHOW Y K,et al.Eulerian Finite-element technique for analysis of jack-up spudcan penetration[J].International Journal of Geomechanics,2012,12(1):64-73.
[17]苏芳眉,刘海笑,李洲.基于耦合欧拉-拉格朗日法的锚板在黏土中的极限承载力数值分析[J].岩土力学,2016,37(9):2728-2736.SU Fang-mei,LIU Hai-xiao,LI Zhou.Analysis of ultimate bearing capacity of plate anchors in clay using a coupled Eulerian-Lagrangian method[J].Rock and Soil Mechanics,2016,37(9):2728-2736.
[18]刘润,刘文彬,洪兆徽,等.海底管线整体屈曲过程中土体水平向阻力模型研究[J].岩土力学,2015,36(9):2433-2441.LIU Run,LIU Wen-bin,HONG Zhao-hui,et al.A soil resistance model for subsea pipeline global lateral buckling analysis[J].Rock and Soil Mechanics,2015,36(9):2433-2441.
[19]EINAV I,RANDOLPH M F.Combining upper bound and strain path methods for evaluating penetration resistance[J].International Journal for Numerical Methods in Engineering,2005,63(14):1991-2016.
[20]KVALSTAD T J,NADIM F,ARBITZ C B.Deepwater geohazards:geotechnical concerns and solutions[C]//Offshore Technology Conference.[S.l.]:[s.n.],2001:1-11.
[2]WESTGATE Z J,RANDOLPH M F,WHITE D J,et al.The influence of sea state on as-laid pipeline embedment:a case study[J].Applied Ocean Research,2010,32(3):321-331.
[3]LIM S J.An experimental investigation of pipeline stability in very soft clay[D].Houston:University of Houston,1974.
[4]RANDOLPH M F,HOULSBY G T.The limiting pressure on a circular pile loaded laterally in cohesive soil[J].Géotechnique,1984,36(3):457-457.
[5]MURFF J D,WAGNER D A,RANDOLPH M F.Pipe penetration in cohesive soil[J].Géotechnique,1989,39(2):213-229.
[6]DINGLE H RC,WHITE D J W J,GAUDIN C G.Mechanisms of pipe embedment and lateral breakout on soft clay[J].Canadian Geotechnical Journal,2008,45(5):636-652.
[7]AUBENY C P,SHI H,MURFF J D.Collapse loads for a cylinder embedded in trench in cohesive soil[J].International Journal of Geomechanics,2005,5(4):320-325.
[8]WANG D,WHITE D J,RANDOLPH M F.Large-deformation finite element analysis of pipe penetration and large-amplitude lateral displacement[J].Canadian Geotechnical Journal,2010,47(8):842-856.
[9]CHATTERJEE S,RANDOLPH M F,WHITE D J.The effects of penetration rate and strain softening on the vertical penetration resistance of seabed pipelines[J].Géotechnique,2012,62(7):573-582.
[10]DUTTA S,HAWLADER B,PHILLIPS R.Finite element modeling of partially embedded pipelines in clay seabed using coupled Eulerian-Lagrangian method[J].Canadian Geotechnical Journal,2015,52(1):58-72.
[11]MERIFIELD R S,WHITE D J,RANDOLPH M F.Effect of surface heave on response of partially embedded pipelines on clay[J].Journal of Geotechnical&Geoenvironmental Engineering,2009,135(6):819-829.
[12]CATHIE D N,JAECK C,BALLARD J C,et al.Pipeline geotechnics-state-of-the-art[C]//International Symposium on the Frontiers in Offshore Geotechnics.Perth:Taylor and Francis,2005:95-114.
[13]SENTHILKUMAR M,RAJEEV P,ROBERT D J,et al.Undrained load-displacement behavior of partially embedded pipeline on seabed[J].Journal of Pipeline Systems Engineering and Practice,2015,7(1):04015016.
[14]Abaqus(2010).Standard user’s manual,Abaqus 6.10[M].Providence,RI,USA:Dassault Syste`mes Simulia Corp,2010.
[15]闫澍旺,林澍,霍知亮,等.桶形基础液压下沉过程的耦合欧拉-拉格朗日有限元法分析[J].岩土力学,2017,38(1):247-252.YAN Shu-wang,LIN Shu,HUO Zhi-liang,et al.Coupled Eulerian-Lagrangian finite element analysis of suction caisson penetration processes under hydraulic pressure[J].Rock and Soil Mechanics,2017,38(1):247-252.
[16]THO K K,LEUNG C F,CHOW Y K,et al.Eulerian Finite-element technique for analysis of jack-up spudcan penetration[J].International Journal of Geomechanics,2012,12(1):64-73.
[17]苏芳眉,刘海笑,李洲.基于耦合欧拉-拉格朗日法的锚板在黏土中的极限承载力数值分析[J].岩土力学,2016,37(9):2728-2736.SU Fang-mei,LIU Hai-xiao,LI Zhou.Analysis of ultimate bearing capacity of plate anchors in clay using a coupled Eulerian-Lagrangian method[J].Rock and Soil Mechanics,2016,37(9):2728-2736.
[18]刘润,刘文彬,洪兆徽,等.海底管线整体屈曲过程中土体水平向阻力模型研究[J].岩土力学,2015,36(9):2433-2441.LIU Run,LIU Wen-bin,HONG Zhao-hui,et al.A soil resistance model for subsea pipeline global lateral buckling analysis[J].Rock and Soil Mechanics,2015,36(9):2433-2441.
[19]EINAV I,RANDOLPH M F.Combining upper bound and strain path methods for evaluating penetration resistance[J].International Journal for Numerical Methods in Engineering,2005,63(14):1991-2016.
[20]KVALSTAD T J,NADIM F,ARBITZ C B.Deepwater geohazards:geotechnical concerns and solutions[C]//Offshore Technology Conference.[S.l.]:[s.n.],2001:1-11.