应用可视化技术研究近海建筑物前海冰堆积过程

【作者】 解福奇；

【导师】 王永学；

【作者基本信息】 大连理工大学 ， 港口、海岸及近海工程， 2004， 硕士

【摘要】 对海冰的断裂、重叠和堆积问题研究是海冰数值模拟和预测、近海结构海冰设计参数可靠性分析的重要内容。由于渤海海冰以动力特征为主，在一定条件下，大面积的浮冰在风和流等诸海洋动力因素的作用下会在建筑物前发生断裂、重叠和堆积。本文根据渤海海冰的特点，研究了近岸海冰冰层在海洋动力因素作用下在斜坡式和半圆型防波堤前的断裂、重叠和堆积问题，并对海冰的堆积过程进行了可视化仿真。 本文假定海冰为粘弹性体，基于海冰满足牛顿定律的动力学方程，在Hopkins的多边块体运动数值模拟基础上，依据海冰堆积经历了冰排运动、变形及断裂，断裂后形成一散体系统的特点，对冰排进行随机离散，利用离散元方法来模拟海冰的堆积过程，并确定合理的初始条件和边界条件，建立了海冰在斜坡式和半圆型结构物前堆积的数值模型。 考虑到海冰爬升堆积过程需要很多几何参数和材质参数，并且数值模拟的输出结果包括海冰破碎后离散块体的位置坐标，整理这些数据既繁琐也不直观。为了优化程序，本文采用了可视化技术。即利用VC++的面向对象性质和OpenGL在图形处理方面的优势，实现数据文件的可视化生成，并且可以利用数值模拟地输出结果实现海冰堆积过程的可视化仿真。 利用海冰运动模拟系统，对冰排与结构物作用分三个方面进行了分析：(1)不同坡度下斜坡式防波堤以及不同潮位下半圆型防波堤前冰排断裂模式、堆积特征及作用于防波堤的冰力；(2)冰排以不同的初始速度分别在不同坡度斜坡式防波堤前以及不同潮位半圆型防波堤前冰排断裂模式、堆积特征、及作用于防波堤的冰力；(3)以不同的搜索频率分别在不同坡度斜坡式防波堤前以及不同潮位半圆型防波堤前冰排断裂模式、堆积特征及作用于防波堤的冰力。 通过分析上述三种情况下冰排在斜坡式防波堤和半圆型防波堤前的冰排断裂模式、堆积特征及冰力特征，得到对海冰堆积过程的规律及其机理性的认识，为以后合理确定我国冰区海上工程建设中的海冰设计荷载提供了科学依据。更多还原

【Abstract】 Developing the study concerned with sea ice breakup, overlapping and pile up is important in analyzing the reliability of sea ice design parameters on offshore structure, sea ice numerical simulation and prediction. Due to the dynamic characteristic of sea ice in Bohai, the floating ice fracture, overlapping and pile up is happened in front of structures under the action of wind and current. According to the characteristic of sea ice in Bohai, the mechanism of ice breakup, overlapping and pile up on inclined breakwater and semi-circle breakwater is analyzed, and the process of sea ice pile up is simulated visually.Assuming the sea ice to be viscous-elastic material and satisfied the Newtonian dynamic theory, the process of sea ice pile up on inclined structure and semi-circle structure is simulated using the discrete element method, which is based on Hopkins multitudinous polygonal blocks numerical simulation. The ice sheet is separated into many blocks with random length and the reasonable initial condition and boundary condition are given.Because the process of sea ice climbing and pile up needs a great many geometry and material parameters, and the output results of numerical simulation program contain ice block position , it is fussy and not intuitionistic to clean up the result. To optimize the program , the visualization technology is applied in this thesis. With the object-oriented property of VC++ and advantage of OpenGL in graphics, the data file is created visually and the interaction of ice sheet with inclined breakwater and semi-circle breakwater is manifested dynamically and visually using the output result of numerical simulation program.With the ice move simulation system, the interaction of ice sheet with structure is analyzed in three aspects: (1) ice sheet rupture mode ,pile up characteristic and the ice force before different gradient inclined breakwater and different water level semi-circle breakwater;(2) ice sheet rupture mode with different initial speed, pile up characteristic and the ice force before different gradient inclined breakwater and different water level semi-circle breakwater;(3) ice sheet rupture mode, pile up characteristic and the ice force before different gradient inclined breakwater and different water level semi-circle breakwater with different search frequency.By analyzing ice sheet rupture mode, pile up characteristic and the ice force, we obtain the disciplinarian of the ice pile up and understand its mechanism. It can be adopted as a reference of sea ice design parameters on offshore structure.更多还原