作用于防波堤上波浪荷载的离心机模拟
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摘要
随着港口码头向深水大吨位化的发展,新扩建防波堤逐渐向深水区延伸,防波堤受到的波浪荷载强度越来越高,当堤基位于海底软黏土层上时,由于地基承载力低,往往考虑轻型防波堤结构,在某一防波堤延伸段工程中就推出了薄壁箱筒型基础防波堤新结构。然而,这类轻型防波堤能否经得住设计波浪荷载的作用以及它的性状为工程师所关注,故希望通过土工离心模型试验,在高速旋转的离心力场中模拟作用于防波堤结构上波浪荷载作用,观察其动态反应特性。根据电磁激励器原理研制开发了一套非接触式循环波浪荷载模拟器系统,能提供不同频率、幅值高达1200 N的不对称周期性往复荷载,满足了波浪荷载模拟需要。文中随后介绍了该装置在箱筒型基础防波堤结构与地基的波浪荷载作用试验中的应用,试验测量了防波堤结构的水平变位、沉降和倾斜以及地基中孔隙水压力等性状反应,基于模型试验结果,探讨了波浪荷载作用下箱筒型基础防波堤的破坏模式,结果发现,主要破坏模式为防波堤倾斜过度而失稳或水平变位超出容许值而发生侧向滑动破坏。
Cylindrical breakwater is a new type of deep-water breakwater, which is proposed to be constructed on soft ground under severe wave loading. As it is not long before the trial section is built, no severe storm has been encountered till now. Therefore, a specific subject study on the cylindrical breakwater by centrifugal model tests is carried out to investigate the response of the cylindrical breakwater subject to the hypothesized wave load in the design. A specific in-flight simulator is developed to create the cyclic action of severe wave force at the appointed frequency. The response of cylindrical breakwater is depicted in terms of the horizontal, vertical and tilt displacements as well as the excess pore water pressure in the soft ground. The effect of height of lower cylinders and ballasting weight in upper cylinders are studied on working performance. Two main modes of failure are finally proposed in the design for the cylindrical breakwater, that is, the lateral translational sliding failure due to short height of lower cylinders and the overturning failure of excessive tilt displacement due to sustaining wave load with long duration.
Cylindrical breakwater is a new type of deep-water breakwater, which is proposed to be constructed on soft ground under severe wave loading. As it is not long before the trial section is built, no severe storm has been encountered till now. Therefore, a specific subject study on the cylindrical breakwater by centrifugal model tests is carried out to investigate the response of the cylindrical breakwater subject to the hypothesized wave load in the design. A specific in-flight simulator is developed to create the cyclic action of severe wave force at the appointed frequency. The response of cylindrical breakwater is depicted in terms of the horizontal, vertical and tilt displacements as well as the excess pore water pressure in the soft ground. The effect of height of lower cylinders and ballasting weight in upper cylinders are studied on working performance. Two main modes of failure are finally proposed in the design for the cylindrical breakwater, that is, the lateral translational sliding failure due to short height of lower cylinders and the overturning failure of excessive tilt displacement due to sustaining wave load with long duration.
引文
[1]谢世楞.坛海港防波堤工程的发展趋势[C]//第九届全国海岸工程学术讨论会论文集.北京:海洋出版社,1999:1–11.(XIE Shi-leng.The development trend of harbor breakwater[C]//Proc 9th Chinese National Conf on Ocean Engineering.Beijing:Ocean Press,1999:1–11.(in Chinese))
[2]李伟.箱型吸力基础防波堤结构探讨[J].港工技术,2001(增刊):75–77.(LI Wei.Discussion on structure of breakwater on box-type suction foundation[J].Port Engineering Technology,2001(S0):75–77.(in Chinese))
[3]SEKIGUCHI H,KITA K,SASSA S,et al Generation of progressive fluid waves in a geo-centrifuge[J].Geotechnical Testing Journal,1998,ASTM,21(2):95–101.
[4]GAO Fu-ping,RANDOLPH M F.Wave generation system in a drum centrifuge and its application[C]//Proc 10th Chinese National Conf on Soil Mechanics and Geotechnical Engineering.Chongqing,2007.
[5]ZHANG X Y,LEUNG C F,LEE F H.Performance of caisson breakwater subjected to breaking wave loads[C]//Frontiers in Offshore Geotechnics.ISFOG-Gourvenec&Caaidy(eds)?2005 Taylor&Francisv Group.London,2005.
[6]张建红,林小静,鲁晓兵.水平荷载作用下张力腿平台吸力式基础的物理模拟[J].岩土工程学报,2007,29(1):77–81.(ZHANG Jian-hong,LIN Xiao-jing,LU Xiao-bing.Physical modelling of suction foundations of TLPs under horizontal loads[J].Chinese Journal of Geotechnical Engineering,2007,29(1):77–81.(in Chinese))
[7]ROWE P W,CRAIG W H,PROCTER D C.Dynamically loaded centrifugal model foundations[C]//Proc 9th ICSMFE.Tokyo,1977:359–364.
[8]蒋敏敏,徐光明,顾行文.离心模型试验饱和黏性土制备和固结分析[C]//土工测试新技术—第25届全国土工测试学术研讨会论文集.杭州,2008:357–378.(JIANG Min-min,XU Guang-ming,GU Xing-wen.Analysis on preparation and consolidation of saturated clay for centrifugal model test[C]//Proceedings of 25th National Symposium on New Geotecnical Testing.Hangzhou,2008:357–378.(in Chinese))
[9]蔡正银,徐光明,顾行文,等.箱筒型基础防波堤离心模型试验研究[R].南京:南京水利科学研究院,2010.(CAI Zheng-yin,XU Guang-ming,GU Xing-wen,et al.Study of cylindrical breakwater by means of centrifuge model tests[R].Nanjing:Nanjing Hydraulic Research Institute,2010.(in Chinese))
[10]前苏联交通建设部全苏十月革命功勋交通科学研究院.有关大直径薄壳码头建筑物计算与设计方法建议[M].莫斯科:海运河运建筑工程总局出版社,1986.(The Traffic Science Research Institute Awarded by October Revolution Feats of the Former Soviet Union.Suggestions on design of large-diameter thin-walled wharf building[M].Moscow:Marine River Transport Construction Engineering Administration,1986.(in Chinese))
[11]范期锦,李乃扬.长江口二期工程北导堤局部破坏的原因及对策[J].中国港湾建设,2004(2):1–8.(FAN Qi-jin,LI Nai-yang.The Reasons and countermeasures for north bank's part failure in the second phase regulation project of Yangtze estuary[J].China Harbor Engineering,2004(2):1–8.(in Chinese))
[12]范期锦.长江口深水航道治理工程的创新[J].中国工程科学,2004,6(12):13–28.(FAN Qi-jin.The innovation of the Yangtze estuary deepwater channel improvement project[J].Engineering Science,2004,6(12):13–28.(in Chinese))
[13]闫澍旺,熊志福,范期锦,等.长江口深水航道治理工程地基土动三轴试验研究综述[J].水运工程,2006(12):148–158.(YAN Shu-wang,XIONG Zhi-fu,FAN Qi-jin,et al.Summarization of dynamic triaxial experimental research on foundation soils for Yangtze estuary deepwater channel regulation project[J].Port&Waterway Engineering,2006(12):148–158.(in Chinese))
[2]李伟.箱型吸力基础防波堤结构探讨[J].港工技术,2001(增刊):75–77.(LI Wei.Discussion on structure of breakwater on box-type suction foundation[J].Port Engineering Technology,2001(S0):75–77.(in Chinese))
[3]SEKIGUCHI H,KITA K,SASSA S,et al Generation of progressive fluid waves in a geo-centrifuge[J].Geotechnical Testing Journal,1998,ASTM,21(2):95–101.
[4]GAO Fu-ping,RANDOLPH M F.Wave generation system in a drum centrifuge and its application[C]//Proc 10th Chinese National Conf on Soil Mechanics and Geotechnical Engineering.Chongqing,2007.
[5]ZHANG X Y,LEUNG C F,LEE F H.Performance of caisson breakwater subjected to breaking wave loads[C]//Frontiers in Offshore Geotechnics.ISFOG-Gourvenec&Caaidy(eds)?2005 Taylor&Francisv Group.London,2005.
[6]张建红,林小静,鲁晓兵.水平荷载作用下张力腿平台吸力式基础的物理模拟[J].岩土工程学报,2007,29(1):77–81.(ZHANG Jian-hong,LIN Xiao-jing,LU Xiao-bing.Physical modelling of suction foundations of TLPs under horizontal loads[J].Chinese Journal of Geotechnical Engineering,2007,29(1):77–81.(in Chinese))
[7]ROWE P W,CRAIG W H,PROCTER D C.Dynamically loaded centrifugal model foundations[C]//Proc 9th ICSMFE.Tokyo,1977:359–364.
[8]蒋敏敏,徐光明,顾行文.离心模型试验饱和黏性土制备和固结分析[C]//土工测试新技术—第25届全国土工测试学术研讨会论文集.杭州,2008:357–378.(JIANG Min-min,XU Guang-ming,GU Xing-wen.Analysis on preparation and consolidation of saturated clay for centrifugal model test[C]//Proceedings of 25th National Symposium on New Geotecnical Testing.Hangzhou,2008:357–378.(in Chinese))
[9]蔡正银,徐光明,顾行文,等.箱筒型基础防波堤离心模型试验研究[R].南京:南京水利科学研究院,2010.(CAI Zheng-yin,XU Guang-ming,GU Xing-wen,et al.Study of cylindrical breakwater by means of centrifuge model tests[R].Nanjing:Nanjing Hydraulic Research Institute,2010.(in Chinese))
[10]前苏联交通建设部全苏十月革命功勋交通科学研究院.有关大直径薄壳码头建筑物计算与设计方法建议[M].莫斯科:海运河运建筑工程总局出版社,1986.(The Traffic Science Research Institute Awarded by October Revolution Feats of the Former Soviet Union.Suggestions on design of large-diameter thin-walled wharf building[M].Moscow:Marine River Transport Construction Engineering Administration,1986.(in Chinese))
[11]范期锦,李乃扬.长江口二期工程北导堤局部破坏的原因及对策[J].中国港湾建设,2004(2):1–8.(FAN Qi-jin,LI Nai-yang.The Reasons and countermeasures for north bank's part failure in the second phase regulation project of Yangtze estuary[J].China Harbor Engineering,2004(2):1–8.(in Chinese))
[12]范期锦.长江口深水航道治理工程的创新[J].中国工程科学,2004,6(12):13–28.(FAN Qi-jin.The innovation of the Yangtze estuary deepwater channel improvement project[J].Engineering Science,2004,6(12):13–28.(in Chinese))
[13]闫澍旺,熊志福,范期锦,等.长江口深水航道治理工程地基土动三轴试验研究综述[J].水运工程,2006(12):148–158.(YAN Shu-wang,XIONG Zhi-fu,FAN Qi-jin,et al.Summarization of dynamic triaxial experimental research on foundation soils for Yangtze estuary deepwater channel regulation project[J].Port&Waterway Engineering,2006(12):148–158.(in Chinese))