基于砂岸侵蚀的新型浮式防波堤结构研究

发布时间：2019-04-10 09:42

【摘要】：海岸带是陆地与海洋相互作用的地带,是海岸线向陆、海两侧扩展一定宽度的带状区域,同时也是海洋开发经济发展的重要基地。生态环境却较为脆弱,极易遭受风暴潮、海平面上升及人类活动等影响发生侵蚀,从而给沿岸居民的生产及生活等造成严重危害,致使沿海地区的工厂坍塌、道路中断、海岸防护林遭破坏以及盐田、农田被海水淹没等。因此,针对砂质海岸开展海岸防护措施研究对于保护海岸带地区免遭破坏具有重要的现实意义。本文选取了莱州湾典型侵蚀砂岸-石虎咀区域为研究对象,通过实地考察及理论方面的分析研究,综合考虑了施工可行性和费用等方面确定选用新型浮式防波堤即“π”型浮式防波堤进行海岸侵蚀防护。浮式结构相比较传统重力式结构具有重量轻、对地基要求低、安放简单、造价较低、海水交换能力强、不会改变水流方向和对生态环境影响小等方面的优点,是一种对生态环境友好、造价低廉的具有发展潜力的结构型式。通过阅读文献和查找资料,对研究区域海洋水动力条件进行了研究,掌握了研究区域的海洋动力特征并统计计算了风、波浪、潮汐等要素。分别对反射型结构与摩擦型结构的消波性能及其运动响应进行分析。讨论了浮式防波堤的三维势流理论和水动力性能理论等并对其推导计算。基于当地环境特点和浮式防波堤相关理论,分别从长度、宽度、吃水深度、系泊系统及材料等方面设计浮式防波堤。新型浮式防波堤采用钢筋混凝土材料,采用三段式连接,为增强结构的迎波面积,向下延长增加了两块挡板,挡板长度为1m,宽度0.2m。从而最终设计结构为“π”型浮式防波堤。系泊缆采用合成纤维绳,其能够承受较大的断裂荷载,沿长度方向每隔24m设置一个系泊缆绳,单个浮式防波堤共设8个,每侧4个,对称分布。分别计算分析了防波堤的浮力、重力和系泊力等,其中在波峰和波谷单独作用下可求得结构的浮力,通过受力分析求得重力和系泊力,由结果可看出结构所受的浮力远大于重力,因此结构能够漂浮在水面,在极端环境下系泊缆的受力能够满足要求,进一步从造价及工程经验方面研究了浮式防波堤的可行性。应用ANSYS软件进行数值模拟,在WORKBENCH中的Hydrodynamic Diffraction和Hydrodynamic Response模块对“π”型浮式防波堤进行建模计算分析。研究了“π”型浮式防波堤的不同来浪方向的运动响应,六个方向的响应幅值及其透射系数,并与传统箱型浮式防波堤进行对比分析,得到新型结构具有更好的消波性能。进一步分析结构在波浪(分别考虑规则波和不规则波)、风等作用下的运动响应和系泊受力情况,数值计算结果表明设计结构能够满足极端环境下的要求,对当地海岸防护具有可行性。
[Abstract]:Coastal zone is the land-ocean interaction zone, is the coastline to land, the two sides of the sea to expand a certain width of the ribbon area, but also an important base for the development of ocean development economy. However, the ecological environment is fragile and vulnerable to storm surges, sea-level rise and human activities, thus causing serious harm to the production and life of coastal residents, resulting in factory collapses and road disruptions in coastal areas. Coastal shelterbelts were destroyed and salt fields, farmland submerged by the sea, and so on. Therefore, the study of coastal protection measures for sandy coast is of great practical significance to protect coastal zone from damage. In this paper, the typical eroded sand bank-Shihuzui area in Laizhou Bay is selected as the research object, and through field investigation and theoretical analysis, Considering the feasibility and cost of construction, a new type floating breakwater named "蟺" floating breakwater is selected for coastal erosion protection. Compared with the traditional gravity structure, floating structure has many advantages, such as light weight, low demand for foundation, simple installation, low cost, strong sea water exchange ability, no change of water flow direction and little influence on ecological environment, etc. The floating structure has the advantages of light weight, low demand for foundation, simple installation, low cost and strong sea water exchange ability. It is an eco-friendly, low-cost structure with potential for development. Through reading the literature and looking up the data, the marine hydrodynamic conditions in the study area are studied, the characteristics of the ocean dynamics in the study area are grasped and the wind, wave and tide elements are calculated statistically. The anti-wave performance and motion response of reflective structure and friction structure are analyzed respectively. The three-dimensional potential flow theory and hydrodynamic performance theory of floating breakwater are discussed and calculated. Based on the local environmental characteristics and the relevant theory of floating breakwater, the floating breakwater is designed from the aspects of length, width, draft depth, mooring system and materials. The new floating breakwater is made of reinforced concrete material and three-segment connection. In order to strengthen the upgoing wave area of the structure, two baffles are added downward, the length of the baffle is 1 m and the width of the baffle is 0.2 m. Thus, the final design structure is "蟺" floating breakwater. The mooring cable is composed of synthetic fiber rope, which can withstand large fracture load. Along the length direction, one mooring rope is arranged every 24 meters, and a single floating breakwater has 8 mooring cables, 4 on each side and symmetrical distribution. The buoyancy, gravity and mooring force of the breakwater are calculated and analyzed respectively, in which the buoyancy of the structure can be obtained under the action of the wave peak and the wave valley, and the gravity and mooring force can be obtained by the force analysis. It can be seen from the results that the buoyancy of the structure is much greater than that of gravity, so the structure can float on the surface of the water and the force of the mooring cable in the extreme environment can meet the requirements. The feasibility of the floating breakwater is further studied from the aspects of cost and engineering experience. The "蟺" floating breakwater is modeled and analyzed by using ANSYS software Hydrodynamic Diffraction and Hydrodynamic Response modules in WORKBENCH. In this paper, the motion response of "蟺" floating breakwater in different direction, the amplitude and transmission coefficient of six directions are studied, and compared with the traditional box type floating breakwater, it is found that the new structure has better wave suppression performance. The motion response and mooring force of the structure under the action of wave (regular wave and irregular wave respectively) and wind are further analyzed. The numerical results show that the designed structure can meet the requirements of extreme environment. It is feasible to protect the local coast.
【学位授予单位】：鲁东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U656.2

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