【作者】 王公伯；

【导师】 李广雪；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2011， 硕士

【摘要】 莱州湾是我国重要的浅海油气区,随着海洋资源和海洋空间的开发利用,对莱州湾西部工程地质环境需要一个全面的认识。本文在实测资料和实验数据的基础上,从地壳稳定性、海床稳定性、地基稳定性和海洋环境四方面着手,对人工岛的安全稳定性进行系统研究,采用理论分析计算和数值模拟的方法对人工岛及工程地质环境稳定性进行研究,采用模糊综合评价方法对人工岛稳定性做出评价。莱州湾西岸区域地壳属于次稳定区域,工程区所在的莱州湾西岸附近,断裂主要有东侧的NNE向郯庐断裂带西支;北侧的NW向张家口-蓬莱强断裂带,晚更新世-全新世垂向运动强烈;北侧的NEE-EW向弱断裂带,规模小,数量多。海域内未有原发性强震出现,周围地区地震大都为浅源地震,北部断裂交汇带有7级以上地震发生,工程区周边陆域地震烈度为Ⅶ度。工程区域海底,地貌单一,坡度约为0.6‰。海床以粉土和粉质粘土为主,较稳定,表层及上部的粉土层和粘性土层不易滑坡,不易发生剪切破坏;但是粉土层及粘性土层中的粉土夹层易发生液化,三角洲沉积粉土层粘粒含量较高不易液化。三角洲沉积层下部的工程软弱层承载力较强(≥200kpa),对工程影响不大;埋藏古河道位于拟建工程区北,要特别注意埋藏古河道边缘的地基强度差异。一般情况下,潮流作用对人工岛影响较小,达到平衡状态需要较长时间,距人工岛90m处冲蚀最深达3m;一般的波浪作用对人工岛的影响也较少,根脚冲蚀较弱;风暴潮对人工岛影响作用较大,一次风暴潮作用能在平衡的人工岛根脚底床上冲蚀3m左右。要特别注意人工岛的护底工程。人工岛稳定性评价研究以区域工程地质为基础,以灾害地质为对象,根据莱州湾西岸工程地质环境特点采用地壳稳定性、海床稳定性、地基稳定性和海洋环境稳定性四大类13个因素作为评价指标,采用基于AHP的模糊综合评价方法,建立“稳定”、“较稳定”、“较不稳定”、“不稳定”四级评价体系,最终得出人工岛所处区域,工程地质环境条件“较稳定”。影响稳定性的主要因素为持力层性质、工程软弱层、海床液化和风暴潮,在设计及施工过程中一定要做好应对。更多还原

【Abstract】 The Laizhou Bay is an important shallow water oil and gas region, with the development of marine resources and spaces and the constructions of offshore engineerings, it’s necessery to get a comprehensive understanding of the engineering geological environment in the western Laizhou Bay.Based on the measured data and experimental data, the paper systemly analysed the engineering geological environment which contents the crust stability, seabed stability, foundation stability, and marine environment. The results of this study are as follows:Characteristics of regional crustal stability: the crusal stability of the engineering is substable according to the activities of the faults and earthquake and the land subsidence.Shallow strata: mainly silt and silty clay. the top floor is silt and silty clay interbedded stratum, and extremely unstable; upper silt floor is the Yellow River deltatic deposits, with low density ,high water content, high compressibility, where there are obvious weak layers; the lower floor is a fluvial and lacustrine sedimentary stratum with high density, this is a good engineering bearing layer. The upper silt floor is not easy landslide, but is easy liquefation, the liquefaction risk of the improved foundation exists; the engineering soft stratum has a fine bearing capacity, impacting little on the engineering.In general, tidal affects little on the artificial island, it needs a long time for the seabed to reach a equilibrium, the biggest erosion can reach 3m; normal waves affect little on the artificial island, too; storm surges affect on the artificial island much, the balanced seabed can be eroded 3m or so by a storm surge action. So it should pay special attention to bottom protection projects.The stability evaluation of the artificial island is based on regional engineering geology and sets geological disasters as objects, according to engineering geological environment characteristics of the west Laizhou Bay, Using the fuzzy comprehensive evaluation method, the stability of engineering geological environment of an artificial island was evaluated, and an evaluation system for assessing the stability of artificial islands was established. Thirteen influential factors were selected as the evaluation index, which were classified into four categories, i.e.: regional crustal stability (including geologic structure features, seismic intensity, and ground subsidence), seabed stability (including topography, liquefaction, and scouring), foundation stability (including bearing stratum, engineering soft stratum, and buried ancient channel), and marine environment stability (including storm surges, tidal current, wave height, and water depth). The AHP method was used to weigh those factors. The research results would be helpful to the construction and safety estimation of artificial islands更多还原