近海风机吸力式沉箱基础复杂荷载作用下极限承载力的有限元极限分析

发布时间：2018-01-21 01:23

本文关键词： 海上风电吸力式沉箱基础极限承载力有限元极限分析土体-结构裂缝　出处：《土木工程学报》2015年10期 　论文类型：期刊论文

【摘要】：吸力沉箱作为近海大型风机新型基础形式具有诸多优点。极限承载力设计,作为该基础形式设计阶段的关键一环,在设计理论和验算方法方面还不够完善。利用有限元极限分析,对福建某待建海上风电场的5MW风机吸力式沉箱基础选型方案进行承载力分析。提出基于极限分析的土体-结构潜在浸水裂缝模型能够在程序优化过程中自动判断土体-结构界面的浸水裂缝开展。分别给出不同深径比以及是否允许裂缝开展时吸力沉箱不排水极限承载力的计算包络图和安全系数。将计算结果与经验公式、极限平衡解、塑性上限解和有限元解进行比较,验证了结果的准确性。分析表明,吸力式沉箱基础在该工程极限荷载作用下能够满足稳定性要求。允许存在潜在浸水裂缝时,沉箱极限承载力较不允许时低约3%~11%,二者失效机制和土体塑性区分布明显不同。极限状态下沉箱内部土体是否进入塑性与沉箱深径比有关;传统极限平衡法和极限分析多采用桶内土体刚性假定,将高估沉箱的极限承载力。
[Abstract]:As a new type of foundation form of offshore large fan, suction caisson has many advantages. The design of ultimate bearing capacity is a key link in the design stage of this foundation form. The design theory and checking method are not perfect enough. The finite element limit analysis is used. Carrying capacity analysis of suction caisson foundation selection scheme of 5MW fan in an offshore wind farm to be built in Fujian Province is carried out. A soil-structure potential soaking crack model based on limit analysis is put forward, which can be automatically applied in the process of program optimization. The calculation envelope diagram and safety factor of ultimate bearing capacity of suction caisson under different depth / diameter ratio and whether cracks are allowed to be carried out are given respectively. The calculation results are compared with the experience in determining the expansion of soaking cracks at the soil-structure interface. Style. The limit equilibrium solution, the plastic upper bound solution and the finite element solution are compared to verify the accuracy of the results. The suction caisson foundation can meet the requirements of stability under the limit load of the project. When the potential immersion cracks are allowed, the ultimate bearing capacity of caisson is about 311% lower than that of non-allowable caisson foundation. The failure mechanism and the distribution of plastic zone of soil are obviously different between them. Whether the soil in caissons enters plastic or not under the limit state is related to the ratio of depth to diameter of caissons. The traditional limit equilibrium method and limit analysis usually adopt the rigid assumption of soil in the bucket, which will overestimate the ultimate bearing capacity of caisson.
【作者单位】：清华大学;麻省理工学院;
【基金】：国家留学基金
【分类号】：TU476.1
【正文快照】： 引言海上风电由于资源丰富、噪声小、风速稳定、零污染等诸多优点,得到了世界各国的广泛重视。传统的海上风电基础形式可分为单桩式、多桩式以及重力式。其中,多桩式又分为多桩承台、三脚架、四脚架和导管架结构。欧洲地区多采用单桩式、重力式、三脚架式和导管架式,主要分布

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