自升式平台起放桩过程动力学行为研究

发布时间：2018-08-13 12:56

【摘要】：起放桩过程是自升式海洋平台动力响应研究的关键之一。放桩是将桩腿下放至海底的过程,起桩是将桩腿从海底向上起升的过程。桩腿起放过程平台处于漂浮状态,随着桩腿的起放,桩腿与主体之间的相对位置不断改变,平台的某些结构参数如重心、浮心等也会发生变化,从而引起包括固有频率、刚度等在内的平台动力学性能随时间而不断演化,并且平台所承受的外部环境载荷也随时间不断变化。同时不同升降系统之间,升降系统机构运动与平台系统结构响应之间存在着复杂的相互作用关系。桩腿下放至触底瞬间时,升降系统承受巨大的冲击载荷,严重影响平台作业安全。鉴于此,本文基于有限元分析软件和动力学分析软件,对起放桩过程中的平台整体和升降系统的动力学响应展开研究,主要工作如下:(1)考虑自升式平台起放桩过程中处于漂浮状态,首先对平台漂浮状态下的运动响应进行分析。基于AQWA水动力学软件和ADAMS动力学分析软件,对自升式平台六自由度运动响应进行仿真分析。以此为基础,研究桩腿不同起放位置下的平台运动幅值响应算子RAO,以及平台运动响应对海况等级、桩腿升降、波浪方向、桩腿刚柔性等因素的敏感性,为自升式平台起放桩作业安全提供理论依据。(2)升降系统是自升式平台的关键部分,起放桩过程承受动载和重载,对其进行动力学特性的研究非常有必要。基于ADAMS软件,对自升式平台刚柔耦合模型进行动力学分析,进而研究齿轮齿条升降系统运动及动力学特性。重点对自升式平台起放桩过程和触底瞬间的升降系统齿轮齿条运动特性和接触载荷进行研究,并对升降系统动力学特性影响因素进行对比分析。(3)平台起放桩过程自身的动力学性能不断演化,同时承受的环境载荷也随时间不断变化,因此对其进行整体动力学分析有着重要的意义。基于ANSYS软件对自升式平台进行模态分析和结构安全性能分析,研究桩腿不同起放位置下的平台固有特性和结构强度变化,进而研究桩腿起放对平台整体动力学性能的影响,为自升式平台起放桩作业安全提供理论依据。
[Abstract]:The process of pile lifting is one of the key points in the study of dynamic response of jack-up offshore platform. Piling is the process of lowering the leg of the pile to the bottom of the sea and lifting the leg of the pile from the bottom of the sea. The platform is floating in the process of pile-leg lifting, and the relative position between the pile-leg and the main body changes continuously with the pile-leg release, and some structural parameters of the platform, such as the center of gravity and the floating center, will also change, resulting in the natural frequency. The dynamic performance of the platform, including stiffness and so on, evolves with time, and the external environmental load of the platform changes with time. At the same time, there is a complex interaction relationship between the motion of the lifting system mechanism and the structural response of the platform system. When the pile leg is lowered to the bottom, the lifting system is subjected to huge impact load, which seriously affects the safety of platform operation. In view of this, based on finite element analysis software and dynamic analysis software, the dynamic response of the whole platform and lifting system in the process of pile lifting and releasing is studied in this paper. The main work is as follows: (1) considering the floating state of the lifting platform, the motion response of the platform in the floating state is analyzed firstly. Based on AQWA hydrodynamic software and ADAMS dynamic analysis software, the six degree of freedom motion response of the jack-up platform is simulated and analyzed. Based on this, the amplitude response operator RAO of platform motion in different position of pile leg is studied, and the sensitivity of platform motion response to sea condition grade, lifting and lifting of pile leg, wave direction, stiffness and flexibility of pile leg are studied. (2) lifting and lifting system is the key part of self-lifting platform, and it is necessary to study the dynamic characteristics of the lifting pile. Based on ADAMS software, the dynamic analysis of the rigid-flexible coupling model of the jack-up platform is carried out, and the motion and dynamic characteristics of the gear rack lifting system are studied. The kinematic characteristics and contact load of gear rack in lifting and lifting system of self-lifting platform during pile lifting and at the moment of touching bottom are mainly studied. The factors affecting the dynamic characteristics of the lifting system are compared and analyzed. (3) the dynamic performance of the platform during the pile lifting and releasing process is constantly evolving, and the environmental load on the platform is also changing with time. Therefore, it is of great significance to analyze the whole dynamics. Based on the ANSYS software, the modal analysis and structural safety performance analysis of the jack-up platform are carried out. The inherent characteristics and structural strength changes of the platform under different lifting and releasing positions of the pile leg are studied, and the influence of the lifting and releasing of the pile leg on the overall dynamic performance of the platform is studied. It provides a theoretical basis for the safety of lifting and laying piles on a self-elevating platform.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE95

【相似文献】