【作者】 李勇；

【导师】 史庆增；

【作者基本信息】 天津大学 ， 港口、海岸与近海工程， 2004， 硕士

【摘要】 随着海上工程活动不断向规模化发展,海冰对结构物作用的问题日益突出,冰区结构物的合理设计和安全运行越来越引起科技界和工程界的重视。锥体结构因其减小水平冰力的优势而成为寒区海洋工程的优选结构。工程实际中冰激锥体振动现象的发生对锥体动冰力的研究提出了强烈的需求,冰激锥体结构振动成为锥体冰力问题中一个重要的研究方向。本篇论文以JZ20-2海区安装正倒锥组合体的导管架平台为工程背景,在天津大学冰工程实验室进行了冰激锥体振动的模型试验研究,获得了大量的数据,并取得了一定的成果。在本文中,通过对冰激锥体振动试验现象的观察、试验数据的分析,提出了双峰值的冰激锥体振动概化动冰力函数;通过对概化动冰力函数里第一冰力峰值和锥体静冰力里极值冰力的对比分析,提出结构柔性会造成第一冰力峰值小于极值冰力;通过对概化动冰力函数里第一冰力峰值和第二冰力峰值之比与径厚比及冰速之间关系的分析讨论,提出冰速对双峰值之比的影响不是很明显,而径厚比对双峰值之比的影响近似成线性,并给出了径厚比与双峰值之比之间的变化关系;给出了冰排断裂长度与冰厚之间的关系,获得了冰力周期的表达式;通过对大量试验数据的统计分析,确定了冰排对锥体的作用过程中,两次断裂过程的加载时间和卸载时间与冰力周期之间的比例关系,最终建立了冰激锥体振动的概化动冰力函数。更多还原

【Abstract】 As ocean engineering is developing extensively, the affect of sea ice on structurebecomes important. Therefore, reasonable design and safe operation of structure incold region has gained more attention in both scientific and engineering area. Conicalstructure is a good choice in cold region because of its advantage in reducinghorizontal ice force. Ice induced cone vibration in the real life has brought a strongdemand in the research of dynamic ice force on conical structure and it has alsobecome an important direction in the research of ice force on the cone.Using a jacket platform with up-bending and down-bending cone in the JZ20-2Sea field as the engineering background, this paper has studied ice-induced conevibration by the means of model test in the ice engineering laboratory of TianjinUniversity, gained a lot of data, and achieved some accomplishments. With theobservation of the test phenomena and the analysis of testing data, a two-peakice-induced cone vibration ice force function is proposed. By the comparison of firstpeak ice force in dynamic ice force and peak ice force in static ice force, theassumption that the flexibility of the structure will reduce the first peak ice force isprovided. The ratio between the first peak ice force and the second peak ice force iscompared with diameter/ice thickness ratio and ice speed. The result is ice speed haslittle effect on the ratio between two peak ice forces, while diameter/ice thicknessratio is almost linear to the ratio between two peak ice forces and the relation betweenthem is expressed in a formula. Meanwhile, the period of ice force is gained with thehelp of the relation between breaking length and ice thickness. Through statisticalanalysis of the testing data, the ratio between loading/unloading time in the twobreaking processes and ice force period is gained. With all the above conclusion, theice-induced cone vibration ice force function is finally determined.更多还原