鱼雷锚贯入过程的数值研究

发布时间：2018-03-16 06:44

本文选题：鱼雷锚　切入点：贯入速度　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：如今世界上很多国家的油气勘探重点由浅海向深海转移,而安全稳定的系泊基础对于大型的深水油气勘探设备非常重要。鱼雷锚是一种新型高承载力的深水系泊基础,已应用到FPSO等设备的系泊系统中,经过实际工程验证,完全满足海上设施的系泊要求。本文针对鱼雷锚安装的两大过程进行模拟计算,包括水中加速运动过程和贯入海床土层过程。文中详细分析了鱼雷锚及其锚链在水中运动时的受力情况,给出数学模型并进行数值计算,得到鱼雷锚释放高度与初始贯入速度之间的关系。同时利用Abaqus建模对该过程进行数值模拟,将所得结果与Matlab计算结果进行比较分析,得到鱼雷锚水中运动的一般规律,给出释放高度的选择建议。贯入海床过程中,鱼雷锚将克服锚端压力和侧摩阻力在海床中运动,文中将其贯入过程分为三个阶段：浸入阶段、稳定贯入阶段、停止阶段,并通过探究土层单元压力变化分析各个阶段的锚速变化原因,发现了鱼雷锚和土层发生分离导致停止阶段速度变化复杂这一现象。初始贯入深度与海床土层的密度、黏聚力、内摩擦角有关,文中选取三种类型的粘土进行模拟并比较贯入深度；锚端形状参数会影响端部压力的分布,从而影响贯入深度,流线型的锚端更容易贯入土层；鱼雷锚自重增加会使其表面积增加,侧摩阻力也会因此变大,所以鱼雷锚重量应适当选取,并非一味求大；初始贯入速度的选取不仅要满足贯入深度的要求,还应兼顾考虑精确性。由于复杂的海洋环境,鱼雷锚及其锚链在水中受到诸如海流、礁石撞击等载荷后其运动方向会发生倾斜,偏离竖直运动,此时鱼雷锚的方向稳定性至关重要。由于初始贯入角的存在,鱼雷锚的贯入过程会大幅度偏离竖直线,影响贯入深度,文中对该问题也进行了模拟分析。
[Abstract]:Nowadays, oil and gas exploration in many countries in the world is shifting from shallow sea to deep sea, and safe and stable mooring foundation is very important for large deepwater oil and gas exploration equipment. Torpedo anchor is a new type of deep-water mooring foundation with high bearing capacity. It has been applied to the mooring system of FPSO and other equipment. After practical engineering verification, it fully meets the mooring requirements of offshore facilities. In this paper, the two major processes of torpedo anchor installation are simulated and calculated. In this paper, the stress of torpedo anchor and its chain in the water is analyzed in detail, and the mathematical model is given and the numerical calculation is carried out. The relationship between the release height of torpedo anchor and the initial penetration velocity is obtained. At the same time, the numerical simulation of the process is carried out by using the Abaqus model. The results are compared with the results of the Matlab calculation, and the general law of the torpedo anchor motion in the water is obtained. In the process of penetration, the torpedo anchor will overcome the pressure at the end of the anchor and the side friction to move in the seabed. In this paper, the penetration process is divided into three stages: immersion stage, steady penetration stage, and stop stage. By analyzing the reasons for the variation of anchoring velocity in each stage, it is found that the separation of torpedo anchor and soil layer leads to the complex variation of the velocity in the stop stage, the initial penetration depth, the density and cohesion of the seabed soil layer, the initial penetration depth, the density of the seabed soil layer, the cohesion force, and so on. In this paper, three types of clay are selected to simulate and compare the penetration depth, the shape parameters of the anchor end will affect the distribution of the end pressure, thus the penetration depth will be affected, and the streamlined anchor end will be easier to penetrate into the soil. The increase of the weight of torpedo anchor will increase its surface area and the side friction, so the weight of torpedo anchor should be properly selected, not blindly; the selection of initial penetration velocity should not only meet the requirements of penetration depth, Due to the complexity of the marine environment, torpedo anchors and their anchor chains may tilt and deviate from vertical motion when subjected to loads such as currents and reef impacts in the water, At this point the directional stability of torpedo anchors is very important. Due to the existence of initial penetration angle the penetration process of torpedo anchors will deviate greatly from the vertical line and affect the penetration depth.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P751

【参考文献】