【作者】 魏巍；

【导师】 张浦阳； 吴亚林；

【作者基本信息】 天津大学 ， 建筑与土木工程， 2018， 硕士

【摘要】 吸力式复合筒型基础是一种新型的海上风机基础结构,具有运输方便和施工高效等特点,近年来开始受到工程界的关注。但是在复合筒型基础吸力沉贯安装的过程中,压差过大会造成筒壁出现弯曲变形甚至屈曲破坏的风险;同时,筒型基础的沉贯调平过程机理复杂,可能发生筒体倾斜进而改变筒壁与周围土体的受力模式,出现筒壁“相对弯曲”变形的风险,从而不利于筒型基础的安装施工。本文从对上述筒体发生弯曲变形的两种情况进行分析说明入手,设计了三种模型试验筒:标准直筒、倒锥型筒和正锥型筒,然后通过在砂土中对模型筒进行沉贯试验并记录试验数据,对三个模型筒的沉贯阻力进行对比分析,观察筒壁变形后对不同阶段筒基沉贯阻力的影响,同时对造成该现象的原因从理论公式、挤土效应以及土塞效应等机理进行解释说明;进而下一步针对试验结果,提出了减阻环和压-拔加载等两种减阻措施,分析不同减阻措施对不同试验模型筒沉贯减阻的效果,并给出了相应的施工减阻改良措施。试验结果表明:在同等沉贯深度下,变形模型试验筒体在沉贯过程中相对于标准直筒其沉贯阻力会增加,且倒锥型筒基沉贯阻力增幅最大;减阻环对于筒基沉贯阻力影响因试验筒体形式而异,对倒锥型试验筒减阻效果最为明显;压-拔加载方式对所有模型试验筒均有减阻效果,但作用程度不一,减阻环会降低压-拔加载方式的减阻效果;现场施工过程中可以参考本文结论,通过改变减阻环形式以及调整压-拔工作方式等措施,对筒型基础的现场沉贯施工减阻具有指导意义。更多还原

【Abstract】 The large-scale suction composite bucket foundation is a new type of foundation for offshore wind turbines.It begins to receive attention from engineering field for the feature of convenient transportation and construction recently.However,a relative higher pressure difference will lead to the bending deformation of the bucket wall and even the buckling failure during the penetration.In addition,the leveling process of foundations is complicated.The bucket is more likely to tilt,thus leading to the variation of force patterns between the bucket walls and surrounding soil and the increasing risk of analogous deformation of bucket walls,which will be detrimental to the installation process.In this paper,two kinds of bending deformation analyses were conducted;and three types of models were made,the standard straight bucket,the inverted cone bucket and the positive cone bucket.Bucket penetration tests in sand were conducted and the penetration resistance was analyzed.Meanwhile,effects of bending deformation at different penetration stages were observed.Finally,two kinds of anti-resisatance measures,the resistance reduction ring and the press-pull loading,were proposed.In conclusion,the penetration resistance of the deformed models was much higher than that of the standard bucket model with the same penetration depth.Particularly,the biggest penetration resistance occurred in the inverted cone bucket model.Moreove,the impact of resistance reduction ring varies with different forms of bucket foundations.An obvious resistance reduction presented in the inverted cone bucket test results.In addition,the resistance reduction effects of press-pull loading tests can be applied to all models with different degrees,but it can be weakened by the resistance reduction ring.The conclusions above can be valuable when it comes to the site installation.By changing the geometry form of the reduction ring and adjusting the application mode of the press-pull measure,it will be of great significance to the penetration resisitance reduction of bucket foundations during the installation.更多还原