【作者】 龚良平；

【导师】 曹立华；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2009， 硕士

【摘要】 为了解埕岛海域自然地质环境对海上构筑物的响应关系,本文通过高分辨率的侧扫声纳、浅地层剖面及单波束测深仪等声学仪器对该海区进行勘查,并结合大量的井场资料、现场和室内实验分析。近几十年来,海浪对海岸线冲蚀越来越严重,对周围的海洋工程设施造成重大的安全威胁。认识人工构筑物与自然地质环境变化的关系,研究海岸线及周边海域在人工构筑物的动力响应,对研究油田钻井平台、海底管线、电缆等人工构筑物对海岸冲刷淘蚀作用以及保护油田设施具有重要的实际意义。埕岛海区在区域自然地质环境作用下,水深呈现逐渐增大的趋势,整体上埕岛海区的冲淤环境处于冲淤调整状态,长期的调整趋势使该海区的水下岸坡坡度逐渐减小。埕岛海区的海底冲淤变化规律是开始时由于黄河改道原因以快速冲刷作用为主,然后逐渐进入缓慢冲刷阶段,最后形成以冲刷为主的冲淤调整期。影响埕岛海区海底地形变化的地质作用主要表现形式有废弃三角洲的冲蚀作用和海底不稳定性地质作用。海底不稳定地质作用的主要方式表现为海底的塌陷凹坑、沉积物碎屑流和局部的滑坡与崩塌。随着胜利油田海上石油的开发,在埕岛海域兴建了大量人工构筑物,如石油平台、海底石油管线、海底电缆等等,其中石油平台的桩柱部分对自然地质环境的影响最为强烈。分析认为,石油平台的修建会对影响其周围的海底地形,石油平台的桩柱的存在,打破了原有的水动力条件环境,造成二次涡旋,在波浪和潮流共同作用下,对海底的地形造成了冲刷,最大冲刷深度可达2.2m,同时在平台周围存在大量不稳定性地貌,例如:侵蚀洼地、蚀余凸起等;海底管线的铺设同样也会对海底的地形造成影响,通过对管线冲刷机理的分析、实测管线路由区不同年份水深值和管线路由区的多波束图像以及浅地层剖面图像的分析解译,认为管线对埕岛海区地形变化影响较大,海底管线的铺设,不仅改变其周围原有的地貌、土体力学等特征,还使水动力条件更加强烈,泥沙更趋于起动,造成对海底地形的冲蚀,最大冲刷深度可达0.3m,在管线附近主要存在塌陷凹坑等不稳定性地貌。埕岛海域上的各式各样的海上人工构筑物群,它们对海底的影响已不再是小范围的局部冲刷海底,而是区域性的改变埕岛海域自然地质环境,自然地质环境同时又影响着人工构筑物的稳定性,它们之间存在着相互相成的关系。埕岛海域大量的人工构筑物群加剧了该海域海底底床的冲刷,使其周围水深逐渐变大,水深等值线明显凸向靠岸一侧,同时,被冲蚀的海底物质在波浪潮流循环荷载的作用下,向人工建筑物附近海域就地填充淤积,形成浅滩,致使该处水深等值线明显凸向海一侧,填充淤积的浅滩又对于保护该区海底管道电缆等路由工程设施的安全具有十分重要的现实意义。本论文定性分析自然地质环境对人工构筑物的反馈作用,不足之处是缺乏定量的深入研究人工构筑物对自然地质环境的数值计算,到目前尚无法建立定量的海域水深等值线变化动力模式。更多还原

【Abstract】 In order to understand the response of natural geological environment to marine structure into Chengdao sea area, this paper is combining the survey data of side-scan sonar, sub-bottom profiler, the single-beam sounder and etc, same with a large number data of well site and experimentation. In recent decades, coastline was been eroded by waves more and more, and it is a big security threat to marine engineering facilities. understanding of the relationship between artificials and natural the geologierocal, studying the response of coastline or near sea to artificial structures, are important practical significance for studying the effect of oil drilling platforms, subsea pipelines, cables and other artificial structures to coastal erosion, as well as corrosion protection of oil facilities.Under the natural geological environment in Chengdao area, the water depth will be increased gradually, the evolution law is from the status of rapid erosion, to washed into the slow phase, final dynamic equilibrium. The main geological changes form of the impact of sea bottom topography in Chengdao, have the abandoned delta of the erosion and geological instability of the seabed. geological The instability of Seabed has embodied in the ways of collapse pits for the seabed, sediment and debris flow landslides and collapsed partially.With the development of Shengli Oil, it have constructed a large number of artificial structures, such as oil platforms, undersea oil pipelines, submarine cables and others, including oil platforms which of some of the piles have very strong impact of natural geological to environmental. The result of analysis show that the construction of oil platforms will affect the surrounding seabed topography, breaking the original hydrodynamic conditions of the environment, causing the second vortex in the waves and the deepest of scour is up to 2.2m, which is under the combined effect of the trend on the seabed. At the same time, there are a large number of unstable landforms around platforms, such as: low-lying land erosion, convex. The pipelines will also impact on the seabed topography. Through the analysis of the mechanism of pipeline erosion, and the depth data measured in different years and the multi-beam images, sub-bottom profiler images, it show that the pipeline have important effect on its terrain, and pipelines are not only change its original surrounding topography and soil characteristics, but also make more intense of the hydrodynamic conditions, finally resulting the erosion of the seabed topography and the largest erosion may up to 0.3m, and there are unstable landforms such collapse pit near pipeline.The influence of manmade buildings to seabed is no longer a small-local but is regional. On the other way, natural geological environment is also affecting the engineering facilities. There is a mutual relationship between each other. The lots of artificial structures increasing the effect to the seabed, so that the contour map of the depth of water is clearly convex the side of the land. Another, the seabed material which had eroded, is filling sediment around the structures and forming a shallow by the circular action of tide wave. So it clear that the contour map of the depth of water near here is clearly convex side of the sea, which have a great practical significance to the protection of cables and other submarine pipeline routing facilities.In this paper, there is only a qualitative analysis of the feedback effect which the geological environment to the artificial structure, there is lack of quantitative in-depth study of the numerical calculation that the influence which artificial structures on the natural geological environment, and have not a model that quantitative calculate changes the contour map of the depth of water in Chengdao waters.更多还原