倾覆船舶扳正过程中的受力分析与计算
发布时间：2018-08-19 20:42
【摘要】：船舶是水上载运的主体,在水上载运过程中有时会发生船舶倾覆事故。打捞倾覆船舶时,一般需要先对倾覆船舶进行扳正,使其达到甲板基本向上姿态。传统制定倾覆船舶扳正方案时,一般根据以往经验指导整个扳正过程,缺乏必要的设计理论与计算方法。针对上述问题,本文采用理论计算与软件仿真模拟相结合的方法,研究了倾覆船舶扳正过程中的力学特性,推导了相关的计算公式,并讨论了浮性、稳性、搁坐力、泥土阻力、扳正速度以及水动力等因素对船舶扳正的影响。基于船舶静力学原理,本文采用Euler角参数建立了倾覆船舶扳正力和力矩模型,提出了利用牛顿迭代法逐次逼近求解扳正力的方法;根据倾覆船舶扳正过程中纵倾角的变化量,推导了二/三维稳性力矩的计算公式;通过分析破舱内进水、自由液面和气穴的情况,提出了倾覆船舶破舱在扳正过程中的四种典型形式,并给出各种形式破舱在扳正过程中转换的界限条件。当船舶搁浅于均质泥土时,本文通过在搁坐区域上建立多个平行于船舶纵轴和横轴的矩形网络,得到了船舶各处的入泥深度,进一步推导了搁坐力分布表达式并求解了泥土对船舶的阻力矩;当船舶搁浅于非均质泥土时,将泥土对船舶的作用分为船舶与海底之间的剪切阻力矩、海底泥土拥土阻力矩和泥土压实阻力矩三种形式,利用M.H.Letoshnev提出的土体单位面积压力和下陷量之间的关系推导了船舶搁坐力计算公式,得到船舶与海底之间的剪切阻力矩;采用Rankine被动土压力理论计算拥土阻力矩,并根据船舶对泥土压缩功得到了船舶压实阻力矩的计算方法。水面倾覆船舶扳正过程模拟计算发现,扳正前期,合理调节自由液体数量和位置可以降低船体稳性有利于扳正;扳正后期,自由液体的数量又是决定倾覆力矩大小的因素之一;而在扳正过程中,破舱倾覆船舶排水量会改变倾覆船舶的稳性并随着破舱进水量的改变而变化;单侧舱室破损降低倾覆船舶稳性,前期有利于扳正,后期却会增加扳正的难度。搁浅倾覆船舶扳正过程模拟计算发现,搁浅倾覆船舶的初始稳距和稳性力矩均较小,而在扳正后期则会产生较大正/负向力矩,需要施加较大的扳正力矩以维持船舶平衡;深水搁浅船舶的初始稳距较大,但其扳正后期需要的扳正力矩较小;当船体多点搁坐或搁坐在软质滩涂时,设置过多的搁坐点不仅降低计算效率,也有增加计算错误几率的风险,在满足船体强度和工况的前提下,可以设置相对重要的搁坐点进行计算。根据刚体动力学理论,建立倾覆船舶扳正的运动方程;基于流体功能原理,推导了惯性类水动力及附加质量的计算方程;利用Taylor展开式得到粘性水动力公式;根据扳正过程中船舶运动的特点,得到粘性水动力的简化算法;基于势流理论推导了海水动压力,进一步由Gauss公式得到规则波和不规则波波浪力计算公式;根据扳正过程中船舶受力特点,选用直接计算方式求解风力,采用Aage C推导的风作用力公式,进一步得到流力计算方法。
[Abstract]:The ship is the main body of the water transportation, and sometimes the ship overturning accident occurs in the course of the water transportation. When salvaging the overturned ship, it is usually necessary to correct the overturned ship first to make it reach the basic upward deck posture. In view of the above problems, this paper studies the mechanical characteristics of overturning ship in the course of rectification by combining theoretical calculation with software simulation, deduces relevant calculation formulas, and discusses the effects of buoyancy, stability, seating force, soil resistance, rectification speed and hydrodynamic forces on the ship's rectification. Based on the principle of ship statics, the Euler angle parameters are used to establish the model of the pulling force and moment of overturning ship, and the Newton iterative method is used to solve the pulling force successively. In the case of water, free surface and cavitation, four typical forms of overturning ship's damaged cabin in the course of correcting are proposed, and the boundary conditions for the conversion of various forms of damaged cabin in the course of correcting are given. When the ship is grounded in heterogeneous soil, the action of the soil on the ship is divided into three forms: the shear resistance moment between the ship and the seabed, the resistance moment of the seabed soil and the resistance moment of the soil compaction. The relationship between the pressure per unit area of the soil and the subsidence put forward by toshnev has deduced the formula for calculating the ship's grounding force and obtained the shear resistance moment between the ship and the seabed. The resistance moment of the ship's compaction is calculated by Rankine's passive earth pressure theory, and the calculation method of the resistance moment of the ship's compaction is obtained according to the ship's compression work to the soil. The simulation calculation of ship alignment shows that the amount and position of free liquids can reduce the stability of ship hull in the early phase of alignment, and the amount of free liquids is one of the factors that determine the magnitude of overturning moment in the later phase of alignment. The results show that the initial stable distance and moment of stability of the ship are small, but the positive / negative moment is large in the latter stage, which is needed. Applying larger pulling moment to maintain the balance of the ship; the initial stable distance of the ship grounded in deep water is larger, but the pulling moment needed in the later period is smaller; when the hull is on multi-point or on soft beach, setting too many berthing points not only reduces the calculation efficiency, but also increases the risk of calculation error, in order to meet the hull strength and to meet the requirements of the ship. Based on the rigid body dynamics theory, the motion equation of overturning ship is established; the calculation equations of inertia hydrodynamic force and additional mass are deduced based on the fluid function principle; the viscous hydrodynamic formula is obtained by Taylor expansion; and the ship transportation in the process of alignment is obtained. The simplified algorithm of viscous hydrodynamics is obtained based on the dynamic characteristics of the ship; the dynamic pressure of the sea water is deduced based on the potential flow theory, and the formulas for calculating the wave forces of regular and irregular waves are derived from the Gauss formula; according to the force characteristics of the ship in the course of rectification, the direct calculation method is selected to solve the wind force, and the wind force formula deduced from Aage C is used to further obtain the wind force formula. To the flow force calculation method.
【学位授予单位】：大连海事大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U676.6
本文编号：2192777
[Abstract]:The ship is the main body of the water transportation, and sometimes the ship overturning accident occurs in the course of the water transportation. When salvaging the overturned ship, it is usually necessary to correct the overturned ship first to make it reach the basic upward deck posture. In view of the above problems, this paper studies the mechanical characteristics of overturning ship in the course of rectification by combining theoretical calculation with software simulation, deduces relevant calculation formulas, and discusses the effects of buoyancy, stability, seating force, soil resistance, rectification speed and hydrodynamic forces on the ship's rectification. Based on the principle of ship statics, the Euler angle parameters are used to establish the model of the pulling force and moment of overturning ship, and the Newton iterative method is used to solve the pulling force successively. In the case of water, free surface and cavitation, four typical forms of overturning ship's damaged cabin in the course of correcting are proposed, and the boundary conditions for the conversion of various forms of damaged cabin in the course of correcting are given. When the ship is grounded in heterogeneous soil, the action of the soil on the ship is divided into three forms: the shear resistance moment between the ship and the seabed, the resistance moment of the seabed soil and the resistance moment of the soil compaction. The relationship between the pressure per unit area of the soil and the subsidence put forward by toshnev has deduced the formula for calculating the ship's grounding force and obtained the shear resistance moment between the ship and the seabed. The resistance moment of the ship's compaction is calculated by Rankine's passive earth pressure theory, and the calculation method of the resistance moment of the ship's compaction is obtained according to the ship's compression work to the soil. The simulation calculation of ship alignment shows that the amount and position of free liquids can reduce the stability of ship hull in the early phase of alignment, and the amount of free liquids is one of the factors that determine the magnitude of overturning moment in the later phase of alignment. The results show that the initial stable distance and moment of stability of the ship are small, but the positive / negative moment is large in the latter stage, which is needed. Applying larger pulling moment to maintain the balance of the ship; the initial stable distance of the ship grounded in deep water is larger, but the pulling moment needed in the later period is smaller; when the hull is on multi-point or on soft beach, setting too many berthing points not only reduces the calculation efficiency, but also increases the risk of calculation error, in order to meet the hull strength and to meet the requirements of the ship. Based on the rigid body dynamics theory, the motion equation of overturning ship is established; the calculation equations of inertia hydrodynamic force and additional mass are deduced based on the fluid function principle; the viscous hydrodynamic formula is obtained by Taylor expansion; and the ship transportation in the process of alignment is obtained. The simplified algorithm of viscous hydrodynamics is obtained based on the dynamic characteristics of the ship; the dynamic pressure of the sea water is deduced based on the potential flow theory, and the formulas for calculating the wave forces of regular and irregular waves are derived from the Gauss formula; according to the force characteristics of the ship in the course of rectification, the direct calculation method is selected to solve the wind force, and the wind force formula deduced from Aage C is used to further obtain the wind force formula. To the flow force calculation method.
【学位授予单位】：大连海事大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：U676.6
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