渤海海冰锥体冰荷载研究

【作者】 于晓；

【导师】 岳前进；

【作者基本信息】 大连理工大学 ， 工程力学， 2001， 硕士

【摘要】 在结冰海域，海冰往往是海洋工程结构的控制环境荷载。大多数导管架结构的抗冰部分都是直立的圆柱结构。早在上世纪七十年代，就有人提出在结构的抗冰部位安装锥体可以降低冰力的假定，随后的二十多年里，寒区各国针对锥体结构的冰荷载进行了大量的室内实验与理论研究。但是，基于原型结构的锥体冰荷载研究则很少，另外，关于锥体结构的动冰力研究也很少见。因此，人们还不能正确的评价安装锥体的实际效果。 本文在综述了以往关于锥体结构冰荷载研究成果的基础上，连续三年参加了现场原型结构锥体冰荷载实验研究，在对大量的实验数据处理过程中，对锥体冰荷载从破坏模式、静冰力幅值、冰力周期、冰与结构作用时间等进行了计算与统计，为理论分析提供了依据，并构造具体的函数形式。具体说来可以概括为以下几方面。（1）回顾与总结了前人所做的锥体结构冰荷载的研究工作，发现 国内外还仅限于理论与室内实验的静冰力确定和探讨，并没 有关于动力的研究，在冰力函数形式与参数的确认上没有形 成统一的体系。对此，在将静冰力的研究成果进行了总结、 筛选的基础上，结合实验数据得到锥体结构的冰力幅值计算 公式；（2）参与渤海原型结构锥体冰荷载实验的具体进行，并独立承担 其中的锥体结构数据分析工作，通过实施压力盒冰力直接测 量与统计分析、平台结构振动位移响应的测量与统计分析以 大连理工大学硕士论文 及现场观录像观测数据的统计分析，观察冰与结构作用的破 坏模式，获得了大量珍贵的第一手数据资料。分析中具体研 究了结构振动中的动力放大现象，并得到冰与锥体作用周 期、作用时间以及冰厚、冰速等各参数的分布形式； 门）根据大量的现场原型观测数据和经验，提出自己的观点，首 次构造了锥体的动冰力函数，以此计算冰激结构振动，进而 为科学的设计平台结构提供服务。 以上的工作仅是冰荷载研究的一部分，如压力盒数据与结构 振动响应数据的分析主要都集中在时域方面，巨大的信息量虽然 保证了处理结果的科学完备，但工程应用总是希望会有更方便简 洁的途径，因此频率领域的研究工作也逐步展开，压力盒的频谱 分析，响应的频谱分析等等，都要在今后的工作中得以开展。同 时，对于不同的结构形式和冰区环境，平台在加装了锥体之后虽 然降低了冰力，但却并没有都能起到理想的减振效果，这说明了 在冰力函数的构造中，结构与海冰的其他参量，如结构刚度、锥 角、锥径、冰速等对于冰荷载的影响都不可忽略。因此，在今后 的工作中还需要进行进一步的研究与分析。更多还原

【Abstract】 Offshore structures located in ice infested area need to resist static and dynamic ice force. It is known that most jacket platforms are designed as vertical legs so that ice failures in crushing during ice interacting with the structures. At 1970’s it was proposed that adding ice-breaking cones could significantly reduce ice force and comprehensive theoretical and laboratory tests have conducted on this subjects since then. But we still have no definite answer on this question. It is necessary to evaluate effect of ice-breaking cone by full-scale tests. Otherwise, only few researchers discussed the dynamic ice forces of conical structure.Based on full-scale tests conducted on offshore jacket platforms. The previous researches of ice forces of conical structures are summarized first. It is found for the compliant structures installing ice-breaking cones dynamic ice forces could not be neglected, as ice-breaking frequency could equal to the natural frequency of the structure. It is also found that the static force could be determined through the test data. The whole work is generalized as below:(1) Video analysis- The video analysis is approached in two aspects. Firstly, to give the gist of the theory analysis by observing the failure modes of ice-structure interaction; Secondly, taking ice breaking period, ice breaking length, ice thickness and ice velocity by watching video and local observation.(2) Response analysis- During calculating the data of response of the structure, investigate the vibration amplify phenomenon in detail, and get the displacement amplitude distribution by using the theory of Stat.(3) Ice load panel analysis- Using the ice load panel, we obtain the real ice force in partial, and then calculate the whole ice force of the structure combined with the response analysis, furthermore, we also obtain the ice force amplitude distribution, ice-structure impact time, ice frequency and so on.(4) Through these work above, colligate the static ice force researches, establish the dynamic ice load function of the conical structure.The research of the ice induced vibrations with conical structures is a very complex and systemic procedure. There are many other work need to be done such as the frequence analysis of ice force and structure respondence, and the form of the ice load function is still need to be improved because the angle and diameter of cone, the ice thickness and velocity can not be ignored at all.更多还原