【作者】 罗军；

【导师】 陈云敏； 朱斌；

【作者基本信息】 浙江大学 ， 岩土工程， 2008， 硕士

【摘要】 随着全球经济的快速发展,越来越多的水中结构如桥墩、水中输电塔、钻井平台等出现在世界各地,通航船舶对这些水中结构的撞击将严重影响其安全服役,因此研究水中结构的防船舶撞击问题具有较大的工程意义。长期以来,对于防撞问题,大量学者都致力于基于撞击力控制的结构防撞设计方法研究,然而,柔性高桩结构在水平撞击力作用下将发生较大的变形,撞击过程中主要靠自身的水平变形吸收撞击能量,此时传统的撞击力控制防撞设计方法已不再适用,需深入研究高桩的水平大变形性状并在此基础上探索新的工程防撞设计方法。基于规范“m”法和p-y曲线法,开发了静动力水平荷载作用下桩基变形分析的有限差分程序。开展了高桩基础的水平大变形大比例模型试验,获得了桩基水平大变形情况下的桩身变形及弯矩,建立了水平大变形情况下桩身位移、桩身弯矩、及桩周土反力之间的互推关系,在此基础上提出了合理的双曲线型p-y曲线。不同加载高度的试验表明高桩悬臂长度对桩身位移及弯矩有较大影响,结合所开发的计算程序分析发现桩身位移与高桩悬臂长度比近似呈双折线关系,而桩身最大弯矩则与悬臂长度比近似呈线性关系。基于动力p-y曲线法,建立了运动船舶撞击高桩结构的动力学分析模型,揭示了撞击过程中的能量传递规律及高桩结构的变形机理,发现撞击能量主要通过桩基水平大变形承担且给出了撞击能量与桩身弯矩的相关性。在此基础上提出了高桩结构基于能量控制的防撞设计方法,设计了新型柔性护墩桩式防撞系统,并应用于重大工程。更多还原

【Abstract】 Along with the rapid development of global economic, the generation of water structure increases drastically around the world, such as bridge piers, transmission tower and offshore drilling platforms, which will be seriously affected by ship impact. It is significant to study the anti-collision design methods and the anti-collision systems for these structures. Until recently, most of anti-collision design methods is based on impact force control. Whereas, the flexible elevated piled structure will exhibit large deformation subjected to the impact force, and absorb the impact energy by the deformation of itself, the traditional anti-collision design method is no longer applicable. So studying the lage deformation characteristics of the elevated piled structures and the new anti-collision design method is required.Based on the known "m" method and p-y curve method, the finite-differential programs is developed to study the lateral deformation characteristics of the elevated piles. Large-scale model tests are carried out to study the large deformation characteristics of the elevated pile, and the pile shaft lateral deformation and bending moment are measured. The relationship between shaft lateral displacements, bending moments and soil reactions is established, and a reasonable hyperbolic p-y curve model is proposed. It is found that the pile cantilever length much influences the pile shaft lateral displacement and bending moment. The pile shaft lateral displacement is almost bilinear to the ratio of pile cantilever length, and the pile shaft bending moment is almost linear to the ratio of pile cantilever length.Based on the dynamic p-y curve method, a dynamic model is presented for the collision analysis of the elevated piled structure subjected to a moving ship. With the model, the energy transfermation and the deformation of the elevated piled structure during the collision are studied. It is found that the impact energy mainly transfers to the pile foundation and the relationship between the impact energy and the moment of the pile shaft is given. It is found that there is little difference between results analyzed by static p-y curves method and dynamic p-y curves method respectively. Thus, the static p-y curve method can be used to analyze the elevated piled structure subjected to the ship impact. Further, an anti-collision design method based on energy control for the elevated piled structure is presented, and a new flexible pier-supported anti-collision system is proposed. Finally, these new anti-collison system and new design method are applied to a specific engineering case.更多还原