冰激窄体结构振动的机理与理论模型研究

发布时间：2018-04-30 13:40

本文选题：冰激振动 + 导管架平台　；参考：《大连理工大学》2014年博士论文

【摘要】：海冰与窄体海洋结构(如冰区的导管架平台、自升式钻井平台、桥墩、风电基础、灯塔等)作用会形成交变性的动冰荷载,并在一定条件下引发严重的冰激结构振动。对于导管架石油平台,冰激振动可以导致导管架的结构疲劳破坏,平台甲板上部管线及设施的破坏,以及平台工作人员的不适。目前,动冰荷载的形成机理仍是学术界讨论的课题,柔性窄体抗冰结构的设计规范尚不成熟。为满足冰区抗冰平台的设计需求,保障我国渤海冰区导管架平台的安全运行,有必要对冰激窄体结构振动的机理与理论模型展开深入的研究工作。本文基于渤海导管架平台动冰力原型测量以及室内模型实验数据分析,对直立导管架平台冰激振动过程中海冰破碎的过程与机理进行了深入的分析,对自升式钻井平台桩腿上的齿条对冰荷载的影响进行了研究并提出了渤海自升式钻井平台带齿条桩腿挤压动冰力谱模型,对锥体导管架平台冰激振动问题构造了无量纲参数,明确了各物理量之间的内在关系,并在此基础上建立了针对设计筹建阶段中的渤海锥体导管架平台的冰激振动预报模型。本文主要研究工作如下： (1)基于对直立导管架平台动冰力原型测量数据的分析,证明了基于海冰挤压非同时破碎理论的“低值冰力”公式不适用于直立柔性窄体结构,并通过对海冰挤压破碎过程的分析,给出了直立结构上海冰发生挤压同时破碎的关键机理,即结构与冰板之间的“全接触”。 (2)基于对冰与结构相互作用过程中近场海冰破碎行为的分析,对直立柔性窄体结构冰致自激振动的机理进行了进一步的研究,阐明了海冰与结构相互作用过程中结构回摆冰力随即卸载的机理：在结构回摆的瞬间,冰板内的翼型裂纹扩展至相互贯通,冰板破碎,导致冰力随即卸载。 (3)对冰板作用于正倒锥交界处问题,通过对冰板内应力场的分析,给出了作用于正倒锥交界处冰板的破碎机理,即冰板内裂纹在拉应力与剪应力的共同作用下发生扩展,导致冰板向上或下表面的剥落破碎以及后续的向下或上的弯曲破碎。同时,利用原型测量的结构响应数据证明了冰板作用于正倒锥交界处时锥体依然具有减振效果。 (4)基于对自升式钻井平台冰激振动模型实验的数据分析,给出了自升式钻井平台带齿条桩腿上的挤压冰力的计算方法,即利用带齿条桩腿的“等效直径”和基于海冰挤压同时破碎的挤压冰力公式进行计算。同时,给出了渤海自升式钻井平台带齿条桩腿的挤压动冰力谱的计算方法,即基于渤海圆柱桩腿挤压动冰力谱模型,对带齿条桩腿与海冰接触界面上的各局部挤压动冰力自谱与各局部挤压动冰力之间的互功率谱进行“叠加”计算。 (5)基于对锥体导管架平台冰激振动过程及相关物理参数的分析,构造了无量纲冰速vnd和无量纲结构加速度αnd并进一步利用vnd与αnd构造了锥体导管架平台冰激振动的无量纲参数CAⅡⅤ。利用加拿大国家研究委员会(Canada NRC)水力学中心进行的模型实验数据,指出了CAⅡⅤ的规律与离散性的来源,即当除冰速外的结构参数与冰况参数恒定不变,CAⅡⅤ也基本恒定不变,而当除冰速外的结构参数或冰况参数发生变化,CAⅡⅤ也随之改变。 (6)基于锥体导管架平台冰激振动的无量纲参数CAⅡⅤ,结合锥体导管架平台简化单自由度系统以及渤海窄锥体结构随机冰力谱与随机动冰力函数,建立了针对设计筹建阶段中的渤海锥体导管架平台的冰激振动预报模型。同时,给出了在其他海域建立针对设计筹建阶段中的锥体导管架平台的冰激振动预报模型的方法框架。
[Abstract]:The action of sea ice and narrow ocean structure ( such as jacket platform of ice zone , self - elevating drilling platform , bridge pier , wind power base , lamp tower , etc . ) can form alternating dynamic ice load , and cause serious ice - induced structural vibration under certain conditions . The formation mechanism of dynamic ice load is still not mature . In order to meet the design requirement of anti - icing platform in ice zone , it is necessary to study the mechanism and theoretical model of ice - induced narrow body structure vibration .

Based on the prototype measurement of dynamic ice force of the platform platform of Bohai Sea and the experimental data analysis of the indoor model , the process and mechanism of ice breaking in the ice - induced vibration of the platform of the riser are analyzed in depth , and the influence of the rack on the ice load in the self - elevating drilling platform is studied and the intrinsic relationship between the physical quantities is defined . Based on this , an ice - induced vibration prediction model for the platform of the Bohai cone jacket is established .

The main work of this paper is as follows :

( 1 ) Based on the analysis of the prototype measurement data of the dynamic ice force of the stand platform , it is proved that the formula of " low value ice force " based on the non - simultaneous crushing theory of sea ice extrusion is not applicable to the upright flexible narrow body structure , and the key mechanism of simultaneous crushing of the vertical structure Shanghai ice is given through the analysis of the crushing process of the sea ice extrusion , that is , the " full contact " between the structure and the ice sheet .

( 2 ) Based on the analysis of the near - field sea ice breaking behavior during the interaction of ice and structure , the mechanism of self - excited vibration of the vertical flexible narrow body structure is further studied .

( 3 ) The fracture mechanism of the ice sheet acting on the junction of positive and reverse taper is given by the analysis of the stress field in the ice sheet , that is , the crack in the ice sheet expands under the joint action of tensile stress and shear stress , which results in spalling and crushing of the upper or lower surface of the ice plate and subsequent downward or upward bending crushing .

( 4 ) Based on the data analysis of the ice - induced vibration model experiment of the self - elevating drilling platform , the calculation method of the extrusion ice force on the rack - and - rack - leg of the self - elevating drilling platform is given .

( 5 ) Based on the analysis of the ice - induced vibration process and related physical parameters of the platform ice - frame platform , the dimensionless parameters CA 鈪 of dimensionless ice velocity vnd and dimensionless structure acceleration 伪nd were constructed .

( 6 ) Based on the dimensionless parameter CA 鈪 of the ice - induced vibration of the cone - pipe - frame platform , the ice - induced vibration prediction model for the Bohai cone jacket platform in the design stage is established by combining the random ice force spectrum of the single - degree - of - freedom system and the narrow cone structure of the Bohai Sea and the random ice force spectrum of the narrow - cone structure of the Bohai Sea . At the same time , the method framework for establishing the ice - induced vibration prediction model for the cone pipe frame platform in the design stage is established in other sea areas .

【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P75;TB53

【参考文献】