海上风机复合筒型基础负压沉放调平

Suction Installation and Leveling of Composite Bucket Foundation for Offshore Wind Turbines

复合筒型基础是一种巨型宽浅式负压沉箱基础,其筒内设置分舱以对托航、沉放、调平等进行控制.渗流与负压是筒型基础重要的研究内容,而目前尚未发现对复合筒型基础的相关研究.针对复合筒型基础,通过数值模型研究了其沉放调平渗流特性,以出口水力梯度为控制条件,建立了均质砂土中临界负压计算公式,并与无分舱板情况进行比较;最后分析了土质分层和渗流'反作用'对渗流场的影响.结果表明:分舱板使筒型基础沉放临界负压降低约10%,调平临界负压随倾角迅速下降;分层土体中相对渗径变长,临界负压增大,不容易发生渗透破坏;渗流使筒内土体疏松,渗透系数变大,造成内侧土体中水力梯度减小,对土体渗透稳定起到保护作用.

Composite bucket foundation is a kind of large-scale shallow suction caisson,which contains inside bulkheadsto control towing,installation and leveling. The researches on seepage and suction are important forinstallation,but currently there is no correlative study on composite bucket foundation. This paper presents a numericalanalysis of the seepage characteristics of large-scale bucket foundation in both homogeneous and layered soil profile.The formula for critical suction is proposed,with the exit hydraulic gradient as control condition. Then a comparisonis presented between the critical suction of bucket foundation with and without bulkheads. The results showthat the critical suction is reduced by 10% by the bulkheads. Additionally,the analysis of seepage in the suction levelingshows that the critical suction drops rapidly with the increase of dip angle. In the layered soil,the normalizedseepage path increases and the critical suction value grows. The seepage flow loosens the inner sand and increases thepermeability coefficient,which is favorable to the seepage stability of soil.