海冰与锥体抗冰平台相互作用的数值分析
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摘要
随着能源需求量的日益增加，海洋采油平台的设计尤为重要，其中海冰对海洋平台的威胁成为科研人员关注的课题。为避免冰激振动，以显示动力分析软件LS-DYNA为工具，模拟了海冰和海洋平台锥体抗冰结构相互作用的破碎过程。
通过断裂过程的模拟得到了海冰弯曲断裂过程，模拟结果和现场观测一致。海冰的破碎长度符合实测结果。同时模拟结果给出了冰荷载时程曲线，呈现与实测结果一致的三角形脉冲形式。模拟得到了平台上部结构振动的位移和加速度响应信息。
通过数值模拟对海冰断裂过程和冰荷载的影响因素进行分析。首先分析了冰锥接触宽度对破坏模式和断裂长度的影响，结果显示冰锥接触宽度不是破坏模式转变的主要因素，对断裂长度的影响不大。同时分析了锥体角度、海冰厚度、弹性模量和海冰速度对海冰断裂行为的影响程度。针对科研人员关心的冰锥交界处的破碎情况进行了分析，结果表明在冰锥交界处没有发生像海冰与直立结构相互作用一样的挤压破碎情况，海冰仍然表现为弯曲断裂，但冰荷载峰值略高。
文章最后一部分对海冰和渤海JZ20-2海域的MUQ中北和NW北高两个现役海洋平台的相互作用过程进行模拟。结果显示出与实测相近的海冰断裂情况、海冰的断裂长度、冰荷载以及平台振动信息，为海洋平台抗冰结构设计提供参考。
With the increase of energy requirement, it presents the essential requirement from the design of offshore structures. Many researchers have devoted their efforts to the interactions between sea ice and offshore platform. In order to avoiding ice-induced vibration, explicit software LS-DYNA is used to simulate the failure process caused by sea ice impacted with conical platform.
Simulate results indicates that the obtained bending process is consistent with in-situ test. The ice break length belongs to the typical range of in-situ measurements. Ice force exhibits the metrical triangle shape. The simulated results also give the vibration information in platform, such as displacement and acceleration history etc.
The parametric analyses which affect ice failure process and ice force are performed. The ice-cone contact width is not a sensitive factor to the transformation of ice failure mode and break length. The effects of conical angle, ice thickness, elastic modulus and ice velocity also are considered. The simulate result also shows that there is no compress failure process at up-down conical intersection. But the peak force is high compare with other contact positions.
The simulations of two platforms, Bohai JZ20-2 MUQ and NW, are performed in the fifth section, ice failure process, break length, ice force and vibration are consistent with true field experiments. The present results provide the reference to platform design.
通过断裂过程的模拟得到了海冰弯曲断裂过程，模拟结果和现场观测一致。海冰的破碎长度符合实测结果。同时模拟结果给出了冰荷载时程曲线，呈现与实测结果一致的三角形脉冲形式。模拟得到了平台上部结构振动的位移和加速度响应信息。
通过数值模拟对海冰断裂过程和冰荷载的影响因素进行分析。首先分析了冰锥接触宽度对破坏模式和断裂长度的影响，结果显示冰锥接触宽度不是破坏模式转变的主要因素，对断裂长度的影响不大。同时分析了锥体角度、海冰厚度、弹性模量和海冰速度对海冰断裂行为的影响程度。针对科研人员关心的冰锥交界处的破碎情况进行了分析，结果表明在冰锥交界处没有发生像海冰与直立结构相互作用一样的挤压破碎情况，海冰仍然表现为弯曲断裂，但冰荷载峰值略高。
文章最后一部分对海冰和渤海JZ20-2海域的MUQ中北和NW北高两个现役海洋平台的相互作用过程进行模拟。结果显示出与实测相近的海冰断裂情况、海冰的断裂长度、冰荷载以及平台振动信息，为海洋平台抗冰结构设计提供参考。
With the increase of energy requirement, it presents the essential requirement from the design of offshore structures. Many researchers have devoted their efforts to the interactions between sea ice and offshore platform. In order to avoiding ice-induced vibration, explicit software LS-DYNA is used to simulate the failure process caused by sea ice impacted with conical platform.
Simulate results indicates that the obtained bending process is consistent with in-situ test. The ice break length belongs to the typical range of in-situ measurements. Ice force exhibits the metrical triangle shape. The simulated results also give the vibration information in platform, such as displacement and acceleration history etc.
The parametric analyses which affect ice failure process and ice force are performed. The ice-cone contact width is not a sensitive factor to the transformation of ice failure mode and break length. The effects of conical angle, ice thickness, elastic modulus and ice velocity also are considered. The simulate result also shows that there is no compress failure process at up-down conical intersection. But the peak force is high compare with other contact positions.
The simulations of two platforms, Bohai JZ20-2 MUQ and NW, are performed in the fifth section, ice failure process, break length, ice force and vibration are consistent with true field experiments. The present results provide the reference to platform design.
引文
1．曾恒一．我国海洋石油在创新中发展．船舶工业技术经济信息，2000，187：23-29．
2．段梦兰，方华灿等．渤海老二号平台被推倒的调查结论．石油矿场机械，1994．23(3)：1-4．
3. T D Ralston. Plastic Limit Analysis of Sheet Ice Loads Structures. IUTAM Symposium on Physics and Mechanics of Ice, New York, 1980: 289-308.
4. Hirayama K, I Obara. Ice forces on inclined structures Proc. of the 5th International Offshore Mechanic Sand Arctic Engineering, Japan, 1986:515-520.
5. Brown T G, M Maattanen. Comparison of KEMI-I and confederation bridge cone ice load measurement results, Proc, IAHR Symposium on Ice, New Zealand, 2002: 503-513.
6. Yue Q J, Bi X J. Full-scale test and analysis of dynamic interaction between ice sheet and conical structure, Proc. of 14th International Association for Hydraulic Research (IAHR) Symposium on Ice 2, 1998.
7. Yue O.J, Bi X J. Ice Induced Jacket Structure Vibration. Journal of Cold Regions Engineering. 2000, 14 (2): 81-92..
8. Michel B. Ice Mechanics, L'Universite Laval, Quebec, 1978.
9. Hoikkanen. Measurements and analysis of ice force against a conical offshore structure. Proc. Of POAC. 1985, 3:1203-1220
10. Lau M, J M, F M Williams. An analysis of ice breaking pattern and ice piece size around sloping structures. 18th International Conference on Offshore Mechanics and Arctic Engineering, Canada, 1999: 199-207.
11．屈衍，岳前进，C Brister．冰与锥体作用破碎周期及破碎长度分析．冰川冻土，2003，25(2)：26-329．
12. Wessels.E, K K I. ce forces on fixed and floating conical structures. Process of the 9th International IAHR Symposium on Ice. Japan. 1988, Ⅱ: 666-691.
13．李锋，岳前进．不同破坏模式下锥体结构冰力定性分析．大连理工大学学报，2005，45(6)：785-788．
14. Feng Li, Y Q J. An analysis of amplitude and period of alternating ice loads on conical structures. In Proceedings of the 16th IAHR international symposium on ice, New Zealand., 2002, Ⅲ: 16-20.
15．屈衍．海洋结构的冰激振动及冰荷载研究：(博士学位论文)．大连：大连理工大学，2006．
16．李锋，岳前进．窄锥冰力幅值与作用周期分析．力学与实践，2001，23：42-44．
17. Feng L, O J Yue, K N. Shkhinek, A qualitative analysis of breaking length of sheet ice anainst conical structures. Proceeding of 17th POAC ice symposium, 2003: 293-302.
18. Dmitri G, Matskevitch. Velocity effects on conical structure ice loads. Proceeding of 21st International Conference on Offshore Mechanics and Arctic Engineering, Norway, 2002.
19．冯玮．冰排与斜面结构作用时破断长度分析．力学与实践，2005，27：14-17．
20. Yue Q J, et al. Full scale force measurement on JZ20-2 platform. Proc. IAHR Ice Symp, Beijing, 1996: 282-289.
21. Yue Q J, X J Bi. Ice-induced jacket structure vibrations in Bohai Sea. Journal of Cold Regions Engineering, 2000, 14(2): 81-92.
22．岳前进，毕祥军，于晓．锥体结构的冰激振动与冰力函数．土木工程学报，2003．36(2)：p．16-19．
23．曲月霞等．作用于正倒锥结构上冰力物理模拟试验研究．大连理工大学学报，2001，41(3)：231-236．
24. Matskevitch D G. Static and Dynamic Analysis of the Ice-Structure Interaction Under the Slippage Boundary Conditions, Copenhagen, DENMARK. OMAE'95, 14th International Conference on OFFSHORE MECHANICS & ARCTIC ENGINEERING, 1995.
25. Choi K, H O J. Continuum damage modeling for the estimation of ice loads under indentation. Proc. Of the 8th ISOPE, Canada, 1998, Ⅱ: 468-475.
26. B Sand, Horrigmoe G. Simulations of ice forces on sloping structures. Proc. Of the 8th ISOPE, Canada, 1998, Ⅱ: 476-482.
27. B Sand, Horrigmoe G. Simulations of ice ridge forces on conical structures. Proc. Of the 11th ISOPE, Norway, 2001 Ⅰ: 754-759.
28. Derradji-Aouat A, M Lau. Ice Loads on Electric Power Generating Stations in the Bell Isle Strait Proceedings of the 18th International Conference on Port and Ocean Engineering under Arctic Conditions, NY, 2005, Ⅰ: 387-398.
29. Derradji-Aouat, A. Explicit FEA and constitutive modeling of damage and fracture in polycrystalline ice simulations of ice loads on offshore structures. Proceedings of the 18th International Conference on Port and Ocean Engineering under Arctic Conditions, NY, 2005: 225-238.
30. Lau M. A three dimensional discrete element simulation of ice sheet impacting a 60~conical structure. Proceedings of the 16th International Conference on Port and Ocean Engineering under Arctic Conditions. Canada, 2001.
31 丁德文．工程海冰学概论．北京：海洋出版社，1999．
32. Fish A M, Y K. Zaretsky, Strength and Creep of Ice in Terms of Mohr-Coulomb Fracture Theory. International Society of Offshore and Polar Engineers,Golden, Colorado, USA., 1998: p. 416-425.
33. Dempsey J P. Research trends in ice mechanics. International Journal of Solids and Structures, 2000, 37(1-2): 131-153.
34. T D Ralston. An analysis of sheet ice indentation. International Association of Hydraulic Research Symposium on Ice Problems, Lulea, Sweden, 1978.
35. Nadreau J P, B Michel, Yield and failure envelope for ice under multiaxial compressive stresses. Cold Regions Science and Technology, 1986(13): 75-82.
36. Derradji-Aouat A. Multi-surface failure criterion for saline ice in the brittle regime. Cold Regions Science and Technology, 2003, 36: 47-70.
37. John O, Hallquist. LS_DYNA Version 970 Keyword User's Manual. Livermore Software Technology Corporation, 2003.
38 John O, Hallquist. LS_DYNA theory manual. Livermore Software Technology Corporation, 2006.
39. Matskevitch D G. Velocity effects on conical structure ice loads. Proceeding of OMAE'02. 21st International Conference on Offshore Mechanics and Arctic Engineering, Oslo, Norway, 2002: 1-10.
40．李锋等．锥体结构冰荷载速度效应的定性分析．冰川冻土，2003，25：322-325
2．段梦兰，方华灿等．渤海老二号平台被推倒的调查结论．石油矿场机械，1994．23(3)：1-4．
3. T D Ralston. Plastic Limit Analysis of Sheet Ice Loads Structures. IUTAM Symposium on Physics and Mechanics of Ice, New York, 1980: 289-308.
4. Hirayama K, I Obara. Ice forces on inclined structures Proc. of the 5th International Offshore Mechanic Sand Arctic Engineering, Japan, 1986:515-520.
5. Brown T G, M Maattanen. Comparison of KEMI-I and confederation bridge cone ice load measurement results, Proc, IAHR Symposium on Ice, New Zealand, 2002: 503-513.
6. Yue Q J, Bi X J. Full-scale test and analysis of dynamic interaction between ice sheet and conical structure, Proc. of 14th International Association for Hydraulic Research (IAHR) Symposium on Ice 2, 1998.
7. Yue O.J, Bi X J. Ice Induced Jacket Structure Vibration. Journal of Cold Regions Engineering. 2000, 14 (2): 81-92..
8. Michel B. Ice Mechanics, L'Universite Laval, Quebec, 1978.
9. Hoikkanen. Measurements and analysis of ice force against a conical offshore structure. Proc. Of POAC. 1985, 3:1203-1220
10. Lau M, J M, F M Williams. An analysis of ice breaking pattern and ice piece size around sloping structures. 18th International Conference on Offshore Mechanics and Arctic Engineering, Canada, 1999: 199-207.
11．屈衍，岳前进，C Brister．冰与锥体作用破碎周期及破碎长度分析．冰川冻土，2003，25(2)：26-329．
12. Wessels.E, K K I. ce forces on fixed and floating conical structures. Process of the 9th International IAHR Symposium on Ice. Japan. 1988, Ⅱ: 666-691.
13．李锋，岳前进．不同破坏模式下锥体结构冰力定性分析．大连理工大学学报，2005，45(6)：785-788．
14. Feng Li, Y Q J. An analysis of amplitude and period of alternating ice loads on conical structures. In Proceedings of the 16th IAHR international symposium on ice, New Zealand., 2002, Ⅲ: 16-20.
15．屈衍．海洋结构的冰激振动及冰荷载研究：(博士学位论文)．大连：大连理工大学，2006．
16．李锋，岳前进．窄锥冰力幅值与作用周期分析．力学与实践，2001，23：42-44．
17. Feng L, O J Yue, K N. Shkhinek, A qualitative analysis of breaking length of sheet ice anainst conical structures. Proceeding of 17th POAC ice symposium, 2003: 293-302.
18. Dmitri G, Matskevitch. Velocity effects on conical structure ice loads. Proceeding of 21st International Conference on Offshore Mechanics and Arctic Engineering, Norway, 2002.
19．冯玮．冰排与斜面结构作用时破断长度分析．力学与实践，2005，27：14-17．
20. Yue Q J, et al. Full scale force measurement on JZ20-2 platform. Proc. IAHR Ice Symp, Beijing, 1996: 282-289.
21. Yue Q J, X J Bi. Ice-induced jacket structure vibrations in Bohai Sea. Journal of Cold Regions Engineering, 2000, 14(2): 81-92.
22．岳前进，毕祥军，于晓．锥体结构的冰激振动与冰力函数．土木工程学报，2003．36(2)：p．16-19．
23．曲月霞等．作用于正倒锥结构上冰力物理模拟试验研究．大连理工大学学报，2001，41(3)：231-236．
24. Matskevitch D G. Static and Dynamic Analysis of the Ice-Structure Interaction Under the Slippage Boundary Conditions, Copenhagen, DENMARK. OMAE'95, 14th International Conference on OFFSHORE MECHANICS & ARCTIC ENGINEERING, 1995.
25. Choi K, H O J. Continuum damage modeling for the estimation of ice loads under indentation. Proc. Of the 8th ISOPE, Canada, 1998, Ⅱ: 468-475.
26. B Sand, Horrigmoe G. Simulations of ice forces on sloping structures. Proc. Of the 8th ISOPE, Canada, 1998, Ⅱ: 476-482.
27. B Sand, Horrigmoe G. Simulations of ice ridge forces on conical structures. Proc. Of the 11th ISOPE, Norway, 2001 Ⅰ: 754-759.
28. Derradji-Aouat A, M Lau. Ice Loads on Electric Power Generating Stations in the Bell Isle Strait Proceedings of the 18th International Conference on Port and Ocean Engineering under Arctic Conditions, NY, 2005, Ⅰ: 387-398.
29. Derradji-Aouat, A. Explicit FEA and constitutive modeling of damage and fracture in polycrystalline ice simulations of ice loads on offshore structures. Proceedings of the 18th International Conference on Port and Ocean Engineering under Arctic Conditions, NY, 2005: 225-238.
30. Lau M. A three dimensional discrete element simulation of ice sheet impacting a 60~conical structure. Proceedings of the 16th International Conference on Port and Ocean Engineering under Arctic Conditions. Canada, 2001.
31 丁德文．工程海冰学概论．北京：海洋出版社，1999．
32. Fish A M, Y K. Zaretsky, Strength and Creep of Ice in Terms of Mohr-Coulomb Fracture Theory. International Society of Offshore and Polar Engineers,Golden, Colorado, USA., 1998: p. 416-425.
33. Dempsey J P. Research trends in ice mechanics. International Journal of Solids and Structures, 2000, 37(1-2): 131-153.
34. T D Ralston. An analysis of sheet ice indentation. International Association of Hydraulic Research Symposium on Ice Problems, Lulea, Sweden, 1978.
35. Nadreau J P, B Michel, Yield and failure envelope for ice under multiaxial compressive stresses. Cold Regions Science and Technology, 1986(13): 75-82.
36. Derradji-Aouat A. Multi-surface failure criterion for saline ice in the brittle regime. Cold Regions Science and Technology, 2003, 36: 47-70.
37. John O, Hallquist. LS_DYNA Version 970 Keyword User's Manual. Livermore Software Technology Corporation, 2003.
38 John O, Hallquist. LS_DYNA theory manual. Livermore Software Technology Corporation, 2006.
39. Matskevitch D G. Velocity effects on conical structure ice loads. Proceeding of OMAE'02. 21st International Conference on Offshore Mechanics and Arctic Engineering, Oslo, Norway, 2002: 1-10.
40．李锋等．锥体结构冰荷载速度效应的定性分析．冰川冻土，2003，25：322-325