软粘土中张紧式吸力锚承载力理论分析与模型试验
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摘要
随着深水石油开采的发展,张紧式吸力锚成为一个重要的深水海洋平台基础。由于这种基础不同于先前的重力式基础和桩基础,在设计理论上缺少统一的认识。因此评价张紧式吸力锚承载力对于设计此类吸力锚是十分重要的工作。为此本文针对如何评价张紧式吸力锚承载力问题开展了理论分析与模型试验研究。首先,依据塑性极限分析上限理论与极限平衡理论,对张紧式吸力锚极限承载力进行了理论分析,给出相应的计算方法,讨论如何选取计算参数,又针对计算方法特点,编制了相应的计算分析程序。
其次,为了说明评价张紧式吸力锚承载力的塑性极限分析上限法与极限平衡法的可行性,进行了软粘土中张紧式吸力锚承载力模型试验。选取了两个直径试验锚,其长径比分别为4和6,进行了张紧角度为20°、30°、40°吸力锚承载力模型试验。分析了在不同张紧角度下吸力锚的破坏模式,以及张紧角度、长径比的变化对承载力的影响,得出吸力锚的破坏模式与吸力锚受荷角度密切相关,吸力锚的长径比和张紧角度的变化对承载力有很大影响,在相同的张紧角度并且长径比不同的情况下吸力锚最后发生破坏的模式基本没有发生变化。最后用塑性极限分析法和极限平衡分析法与模型试验结果进行了比较和分析。结果表明,这两种理论在评价张紧式吸力锚承载力方面是可行性。
最后,对评价张紧式吸力锚极限承载力的塑性极限分析法和极限平衡分析法在破坏机理与破坏模式、参数选取、求解过程进行了分析和比较。结果表明,塑性极限分析上限法不能反映吸力锚破坏模式,但可以评价吸力锚受荷点不在最佳位置处的承载力,极限平衡分析法能反映吸力锚的破坏模式,但只可以评价吸力锚受荷点在最佳位置处的承载力。
As exploration and production of oil resource progresses into deep waters, suction caissons with taut wires may be an important offshore foundation. However, because the work mechanism of this offshore foundation is different from the traditional gravity foundation and pile foundation, it lacks sophisticated design code at present. So it is important work to evaluate the capacity of suction caissons with taut wires. In this article, the studies are emphasized on the method of theoretical analysis and model tests of suction caisson in clay.
First, the analysis of bearing capacity of suction caissons with taut wires is based on the theories of the upper bound limit analyses and the limiting equilibrium. The formulas of deriving and parametric study are described in this paper. Based on the characteristic of the two methods, I have compiled programs to calculate capacity of suction caissons with taut wires.
Second, model tests of bearing capacity of suction caissons in soft clay were conducted in order to detaile the methods of upper bound limit analyses and limiting equilibrium in calculating reasonably capacity of suction caissons with taut wires. In model test, two suction caissons with slenderness ratio of 4, 6 and the load inclination degrees of 20°, 30°and 40°were used to study the failure mechanism under different load inclination degrees and capacity with different slenderness ratio, different load inclination degrees. We can obtain the capacity of suction caisson is affected by the changes of slenderness ratio and load inclination degrees. We obtained the failure models of suction caisson are affected by the inclination degrees and capacities are changed with different slenderness ratio and load inclination degrees. The failure models of suction caisson are same, when the caissons are with the same inclination degree and different slenderness ratio. The model tests of results are also compared with those from upper bound limit analyses and limiting equilibrium. We obtain that the method of upper bound limit analyses and limiting equilibrium are reasonable on calculating the capacity of suction caisson.
At last, I compared the method of upper bound limit analyses and the method of limiting equilibrium on failure model, failure mechanism, parametric study and course of calculating. The method of upper bound limit analyses can not express the failure model, but the method of limiting equilibrium can express the failure model. The method of upper bound limit analyses can calculate the capacity of suction caissons in the case of rotation at failure. However the method of limiting equilibrium can only calculate the capacity of suction caissons with loading at the optimal loading point (no rotation at failure)
其次,为了说明评价张紧式吸力锚承载力的塑性极限分析上限法与极限平衡法的可行性,进行了软粘土中张紧式吸力锚承载力模型试验。选取了两个直径试验锚,其长径比分别为4和6,进行了张紧角度为20°、30°、40°吸力锚承载力模型试验。分析了在不同张紧角度下吸力锚的破坏模式,以及张紧角度、长径比的变化对承载力的影响,得出吸力锚的破坏模式与吸力锚受荷角度密切相关,吸力锚的长径比和张紧角度的变化对承载力有很大影响,在相同的张紧角度并且长径比不同的情况下吸力锚最后发生破坏的模式基本没有发生变化。最后用塑性极限分析法和极限平衡分析法与模型试验结果进行了比较和分析。结果表明,这两种理论在评价张紧式吸力锚承载力方面是可行性。
最后,对评价张紧式吸力锚极限承载力的塑性极限分析法和极限平衡分析法在破坏机理与破坏模式、参数选取、求解过程进行了分析和比较。结果表明,塑性极限分析上限法不能反映吸力锚破坏模式,但可以评价吸力锚受荷点不在最佳位置处的承载力,极限平衡分析法能反映吸力锚的破坏模式,但只可以评价吸力锚受荷点在最佳位置处的承载力。
As exploration and production of oil resource progresses into deep waters, suction caissons with taut wires may be an important offshore foundation. However, because the work mechanism of this offshore foundation is different from the traditional gravity foundation and pile foundation, it lacks sophisticated design code at present. So it is important work to evaluate the capacity of suction caissons with taut wires. In this article, the studies are emphasized on the method of theoretical analysis and model tests of suction caisson in clay.
First, the analysis of bearing capacity of suction caissons with taut wires is based on the theories of the upper bound limit analyses and the limiting equilibrium. The formulas of deriving and parametric study are described in this paper. Based on the characteristic of the two methods, I have compiled programs to calculate capacity of suction caissons with taut wires.
Second, model tests of bearing capacity of suction caissons in soft clay were conducted in order to detaile the methods of upper bound limit analyses and limiting equilibrium in calculating reasonably capacity of suction caissons with taut wires. In model test, two suction caissons with slenderness ratio of 4, 6 and the load inclination degrees of 20°, 30°and 40°were used to study the failure mechanism under different load inclination degrees and capacity with different slenderness ratio, different load inclination degrees. We can obtain the capacity of suction caisson is affected by the changes of slenderness ratio and load inclination degrees. We obtained the failure models of suction caisson are affected by the inclination degrees and capacities are changed with different slenderness ratio and load inclination degrees. The failure models of suction caisson are same, when the caissons are with the same inclination degree and different slenderness ratio. The model tests of results are also compared with those from upper bound limit analyses and limiting equilibrium. We obtain that the method of upper bound limit analyses and limiting equilibrium are reasonable on calculating the capacity of suction caisson.
At last, I compared the method of upper bound limit analyses and the method of limiting equilibrium on failure model, failure mechanism, parametric study and course of calculating. The method of upper bound limit analyses can not express the failure model, but the method of limiting equilibrium can express the failure model. The method of upper bound limit analyses can calculate the capacity of suction caissons in the case of rotation at failure. However the method of limiting equilibrium can only calculate the capacity of suction caissons with loading at the optimal loading point (no rotation at failure)
引文
[1] El-Sherbiny, Rami M, Performance of Suction Caisson Anchors in Normally Consolidated Clay[D], University of Texas, Austin, August, 2005
[2] Fuglsang, L, Steensen-Bach, J.O, Breakout resistance of suction piles in clay[C], Proc. ISSMFE Centrifuge Conf, Boulder, 1991, 153~159
[3] Deng, W, Carter, J.P, Taiebat, H, Prediction of the Lateral Capacity of Suction Caissons[C], Proceedings,10th International Conference of the International Association for Computer Methods and Advances in Geomechanics, Rotterdam: Balkema, 2001, 33~38
[4] Randolph, M.F, Analysis of suction caisson capacity in clay[C], Proceedings of the 34th annual Offshore Technology Conference, Houston, Texas, May 6-9, 2002, 2145~2155
[5] Jun Huang, Jianchun Cao, Jean M.E, Geotechnical design of suction caissons in clay[C]. Proc. 13th Int. Offshore and Polar Engineering Conference, Honolulu, USA, 2003, 770~779
[6] Luke, A. M, A. F. Rauch, R. E. Olson, Components of Suction Caisson Capacity Measured in Axial Pullout Tests[J], Journal of Ocean Engineering, Elsevier,2003
[7] American Petroleum Institute, Recommended practice for planning, designing, and constructing fixed offshore platforms, API RP2A, 19thed, 1991
[8] Deng W, Carter J P, A theoretical study of the vertical uplift capacity of suction caisson[A], Proc of 10th International Offshore and Polar Engineering Conference[C] 2000
[9] Senpere, D, Auvergne, G.A, Suction anchor piles– a proven alternative to driving or drilling[C]. Proceedings of the 14th annual Offshore Technology Conference, Houston, Texas, OTC 4206, May 3-6, 1982, 483~493
[10] Murff, J.D, and Hamilton, J.M, P-ultimate for undrained analysis of laterally loaded piles[J], Journal of Geotechnical Engineering, ASCE, 1993, 119(1): 91~107
[11] Randolph, M. F, and Houlsby, G. T, The limiting pressure on a circular pile loaded laterally in cohesive soil [J]. Geotechnique, 1984, 34(4):613~623
[12] Aubeny, C.P, Moon, S.K, and Murff, J.D, Lateral undrained resistance of suction caisson anchors[J], International Journal of Offshore and Polar Engineering, 2001,11(2): 95~103
[13] RandolPh, M.F, O, Neill, M.P, Stewart, D.P, Performance of suction anchors in fin-grained calcareous soils[C], Offshore Technology Conference, Houston, Texas, 1998, 521~52
[14]刘振纹,王建华,秦崇仁等,负压筒型基础地基水平承载力研究[J],岩土工程学报,2000,22(6):691~695
[15] Aubeny, C.P, Han, S.W, and Murff, J.D, Inclined load capacity of suction caissons[J], International Journal of Numerical and Analytical Methods in Geomechanics, 2003, 27(14):1235~1254
[16] Charles Aubeny, Seung-Woon Han, James D, Murff, Suction Caisson Capacity in Anisotropic Purely Cohesive Soil[J], International Journal of Geomechanics, ASCE, 2004, 3(2): 225~235
[17] Cho,Y, Bang,S, Inclined Loading Capacity of Suction Piles[C], Proceedings of 12th International Offshore and Polar Engineering Conference, 2002, 827~832
[18] Bransby, M. F, Randolph, M. F, The Effect of Skirted Foundation Shape on Response to Combined V-M-H Loadings[J], International of Offshore and Polar Engineering, 1999, 9(3): 214~218
[19] House, A .R, The response of suction caissons to catenary loading[C], Proceedings of the 4th Australia New Zealand Young Geotechnical Professionals Conference, Perth, Australia, 2000, 119~124
[20] Erbrich, C.T, Modeling of a novel foundation for offshore structures[C], Proceedings of the 9th UK ABAQUS User’s Conference, Oxford, English, 1984
[21] Wang, M.C, Demars, K.R, and Nacci, V.A, Applications of suction anchors in offshore technology[C], Proceedings of the 10th annual Offshore Technology Conference, Houston, Texas, OTC 3203, 1311~1320
[22]栾茂田,范庆来,杨庆,非均质软土地基上吸力式沉箱抗拔承载力数值分析非均质软土地基上吸力式沉箱抗拔承载力数值分析[J],岩土工程学报,2007,29(7):1044~1059
[23] Mark Randolph, Susan Gourvenec, Inclined Pull-out Capacity of Suction Caissons[C], Proceedings of 14th International Offshore and Polar Engineering Conference. Toulon: The International Society of Offshore and Polar Engineers, 2004, 332~339
[24]严宗达,塑性力学[M],天津:天津大学出版社,1988.9
[25] Chairat Supachawarote,Inclined Load Capacity of Suction Caisson in clay[D], University of Western Australia, 2006
[26] Partha Pratim Sharma, Ultimate Capacity of Suction Caisson in Normally and Lightly Overconsolidated Clays, Thesis, University of Texas, Austin. 2004
[27] Murff, J.D, Theoretical Soil Mechanics Class Notes, Department of Civil Engineering, Texas A&M University, College Station, Texas. 2002
[28]张学言,岩土塑性力学[M],天津:天津大学出版社,2003
[29] Clukey E.C, Morrison M.J, A centrifuge and analytical study to evaluate suction caissons for TLP applications in the Gulf of Mexico [J]. Geotechnical Special Publication, ASCE, No.38, 1993, 141~156
[30] K.H. Andersen, J.D. Murff, M.F. Randolph, E.C. Clukey, Suction anchors for deepwater applications[C], Frontiers in Offshore Geotechnics, The Netherlands: Taylor and Francis/Balkema, 2005: 3~30
[31] Andersen, K.H, and Jostad, H.P, Foundation Design of Skirted Foundations and Anchors in Clay[C], Offshore Technology Conference, Houston, Texas, 1999: 383~392
[32] R. Dahlberg, K.O. Ronold, P.J. Str?m, Calibrated Geotechnical Design Code for Suction Anchors in Clay[C], Offshore Technology Conference, Houston, Texas 2006
[33] Chen, W.F, Limit Analysis and Soil Plasticity[M], New York: Elsevier Scientific Publishing Company, 1975
[34]王志云,软土地基上吸力式沉箱基础的抗拔承载特性研究[D],大连:大连理工大学,2008
[35] Seung-Woon Han, The Capacity of Suction Caisson in Isotropic and Nisotropic Cohesive Soils under General Loading[D], Texas A&M University, 2002
[36] Knut H. Andersen, James D. Murff, Mark Randolph, Deepwater Anchor Design Practice– Phase II Report to API/Deepstar Volume II - Suction Caisson Anchors, 2003
[37] DET NORSKE VERITAS, Geotechnical Design and Installation of Suction Anchors in Clay, Recommended Practice DNV-RP-E303, 2005
[38] Brinch-Hansen, J, A Revised and Extended Formula for Bearing Capacity, Geoteknisk Institutt[J], Bulletin No. 28, 1970, 5~11
[39] Andersen, K.H, and Jostad, H.P, Shear Strength along Outside Wall of Suction Anchors in Clay after Installation[C], XII International Symposium on Offshore and Polar Engineering, Kyushu, May 26-31, 2002, 785~794
[40] Randolph, M, Cassidy, M, Gourvenec, S, Challenges of Offshore Geotechnical Engineering[C], Proceedings of the International Conference on Soil Mechanics and Geotechnical Engineering, 2005, 123~176
[41]钱家欢,土工原理与计算[M],中国水利水电出版社,2003
[42] LianyangZhang, FranciscoSilva, RalphGrismala, Ultimate Lateral Resistance to Piles in Cohesionless Soils[J], Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 2005, 131(1): 78~83
[43]孙曦源,栾茂田,唐小微,饱和软黏土地基中桶形基础水平承载力研究[J],岩土力学,2010,31(2):667~671
[44] Andresen, L, Edgers, L, Jostad, H. P, Capacity analysis of suction anchors in clay by Plaxis 3D Foundation[J], Plaxis Bulletin, issue 24, October, 5-9, 2009
[45]中国海洋石油总公司,海上固定平台规划、设计和建造的推荐作法—荷载和抗力系数设计法,中国海洋石油天然气行业标准
[2] Fuglsang, L, Steensen-Bach, J.O, Breakout resistance of suction piles in clay[C], Proc. ISSMFE Centrifuge Conf, Boulder, 1991, 153~159
[3] Deng, W, Carter, J.P, Taiebat, H, Prediction of the Lateral Capacity of Suction Caissons[C], Proceedings,10th International Conference of the International Association for Computer Methods and Advances in Geomechanics, Rotterdam: Balkema, 2001, 33~38
[4] Randolph, M.F, Analysis of suction caisson capacity in clay[C], Proceedings of the 34th annual Offshore Technology Conference, Houston, Texas, May 6-9, 2002, 2145~2155
[5] Jun Huang, Jianchun Cao, Jean M.E, Geotechnical design of suction caissons in clay[C]. Proc. 13th Int. Offshore and Polar Engineering Conference, Honolulu, USA, 2003, 770~779
[6] Luke, A. M, A. F. Rauch, R. E. Olson, Components of Suction Caisson Capacity Measured in Axial Pullout Tests[J], Journal of Ocean Engineering, Elsevier,2003
[7] American Petroleum Institute, Recommended practice for planning, designing, and constructing fixed offshore platforms, API RP2A, 19thed, 1991
[8] Deng W, Carter J P, A theoretical study of the vertical uplift capacity of suction caisson[A], Proc of 10th International Offshore and Polar Engineering Conference[C] 2000
[9] Senpere, D, Auvergne, G.A, Suction anchor piles– a proven alternative to driving or drilling[C]. Proceedings of the 14th annual Offshore Technology Conference, Houston, Texas, OTC 4206, May 3-6, 1982, 483~493
[10] Murff, J.D, and Hamilton, J.M, P-ultimate for undrained analysis of laterally loaded piles[J], Journal of Geotechnical Engineering, ASCE, 1993, 119(1): 91~107
[11] Randolph, M. F, and Houlsby, G. T, The limiting pressure on a circular pile loaded laterally in cohesive soil [J]. Geotechnique, 1984, 34(4):613~623
[12] Aubeny, C.P, Moon, S.K, and Murff, J.D, Lateral undrained resistance of suction caisson anchors[J], International Journal of Offshore and Polar Engineering, 2001,11(2): 95~103
[13] RandolPh, M.F, O, Neill, M.P, Stewart, D.P, Performance of suction anchors in fin-grained calcareous soils[C], Offshore Technology Conference, Houston, Texas, 1998, 521~52
[14]刘振纹,王建华,秦崇仁等,负压筒型基础地基水平承载力研究[J],岩土工程学报,2000,22(6):691~695
[15] Aubeny, C.P, Han, S.W, and Murff, J.D, Inclined load capacity of suction caissons[J], International Journal of Numerical and Analytical Methods in Geomechanics, 2003, 27(14):1235~1254
[16] Charles Aubeny, Seung-Woon Han, James D, Murff, Suction Caisson Capacity in Anisotropic Purely Cohesive Soil[J], International Journal of Geomechanics, ASCE, 2004, 3(2): 225~235
[17] Cho,Y, Bang,S, Inclined Loading Capacity of Suction Piles[C], Proceedings of 12th International Offshore and Polar Engineering Conference, 2002, 827~832
[18] Bransby, M. F, Randolph, M. F, The Effect of Skirted Foundation Shape on Response to Combined V-M-H Loadings[J], International of Offshore and Polar Engineering, 1999, 9(3): 214~218
[19] House, A .R, The response of suction caissons to catenary loading[C], Proceedings of the 4th Australia New Zealand Young Geotechnical Professionals Conference, Perth, Australia, 2000, 119~124
[20] Erbrich, C.T, Modeling of a novel foundation for offshore structures[C], Proceedings of the 9th UK ABAQUS User’s Conference, Oxford, English, 1984
[21] Wang, M.C, Demars, K.R, and Nacci, V.A, Applications of suction anchors in offshore technology[C], Proceedings of the 10th annual Offshore Technology Conference, Houston, Texas, OTC 3203, 1311~1320
[22]栾茂田,范庆来,杨庆,非均质软土地基上吸力式沉箱抗拔承载力数值分析非均质软土地基上吸力式沉箱抗拔承载力数值分析[J],岩土工程学报,2007,29(7):1044~1059
[23] Mark Randolph, Susan Gourvenec, Inclined Pull-out Capacity of Suction Caissons[C], Proceedings of 14th International Offshore and Polar Engineering Conference. Toulon: The International Society of Offshore and Polar Engineers, 2004, 332~339
[24]严宗达,塑性力学[M],天津:天津大学出版社,1988.9
[25] Chairat Supachawarote,Inclined Load Capacity of Suction Caisson in clay[D], University of Western Australia, 2006
[26] Partha Pratim Sharma, Ultimate Capacity of Suction Caisson in Normally and Lightly Overconsolidated Clays, Thesis, University of Texas, Austin. 2004
[27] Murff, J.D, Theoretical Soil Mechanics Class Notes, Department of Civil Engineering, Texas A&M University, College Station, Texas. 2002
[28]张学言,岩土塑性力学[M],天津:天津大学出版社,2003
[29] Clukey E.C, Morrison M.J, A centrifuge and analytical study to evaluate suction caissons for TLP applications in the Gulf of Mexico [J]. Geotechnical Special Publication, ASCE, No.38, 1993, 141~156
[30] K.H. Andersen, J.D. Murff, M.F. Randolph, E.C. Clukey, Suction anchors for deepwater applications[C], Frontiers in Offshore Geotechnics, The Netherlands: Taylor and Francis/Balkema, 2005: 3~30
[31] Andersen, K.H, and Jostad, H.P, Foundation Design of Skirted Foundations and Anchors in Clay[C], Offshore Technology Conference, Houston, Texas, 1999: 383~392
[32] R. Dahlberg, K.O. Ronold, P.J. Str?m, Calibrated Geotechnical Design Code for Suction Anchors in Clay[C], Offshore Technology Conference, Houston, Texas 2006
[33] Chen, W.F, Limit Analysis and Soil Plasticity[M], New York: Elsevier Scientific Publishing Company, 1975
[34]王志云,软土地基上吸力式沉箱基础的抗拔承载特性研究[D],大连:大连理工大学,2008
[35] Seung-Woon Han, The Capacity of Suction Caisson in Isotropic and Nisotropic Cohesive Soils under General Loading[D], Texas A&M University, 2002
[36] Knut H. Andersen, James D. Murff, Mark Randolph, Deepwater Anchor Design Practice– Phase II Report to API/Deepstar Volume II - Suction Caisson Anchors, 2003
[37] DET NORSKE VERITAS, Geotechnical Design and Installation of Suction Anchors in Clay, Recommended Practice DNV-RP-E303, 2005
[38] Brinch-Hansen, J, A Revised and Extended Formula for Bearing Capacity, Geoteknisk Institutt[J], Bulletin No. 28, 1970, 5~11
[39] Andersen, K.H, and Jostad, H.P, Shear Strength along Outside Wall of Suction Anchors in Clay after Installation[C], XII International Symposium on Offshore and Polar Engineering, Kyushu, May 26-31, 2002, 785~794
[40] Randolph, M, Cassidy, M, Gourvenec, S, Challenges of Offshore Geotechnical Engineering[C], Proceedings of the International Conference on Soil Mechanics and Geotechnical Engineering, 2005, 123~176
[41]钱家欢,土工原理与计算[M],中国水利水电出版社,2003
[42] LianyangZhang, FranciscoSilva, RalphGrismala, Ultimate Lateral Resistance to Piles in Cohesionless Soils[J], Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 2005, 131(1): 78~83
[43]孙曦源,栾茂田,唐小微,饱和软黏土地基中桶形基础水平承载力研究[J],岩土力学,2010,31(2):667~671
[44] Andresen, L, Edgers, L, Jostad, H. P, Capacity analysis of suction anchors in clay by Plaxis 3D Foundation[J], Plaxis Bulletin, issue 24, October, 5-9, 2009
[45]中国海洋石油总公司,海上固定平台规划、设计和建造的推荐作法—荷载和抗力系数设计法,中国海洋石油天然气行业标准