海底防沉板-桩复合基础竖向受力变形特性研究

The vertical force and deformation characteristics of subsea mudmat-pile hybrid foundations

为了研究海底防沉板-桩复合基础在竖向荷载作用下的受力变形特性,以我国南海某200m水深项目为研究对象,将防沉板-桩复合基础简化为防沉板加角桩的形式,利用FLAC3D数值模拟软件建立了防沉板-桩复合基础数值计算模型。研究了海底防沉板-桩复合基础在竖向荷载作用下海床土体、防沉板、桩身的受力变形特性,并对不同竖向荷载作用下海床土体沉降、防沉板弯矩、桩身位移、桩身弯矩进行了对比分析。研究表明:防沉板的正负弯矩最大值分别出现在防沉板中部和防沉板与桩顶端的连接处,荷载越大,对防沉板的影响越大,桩在防沉板-桩复合基础中的作用越大;荷载越大,桩身产生的水平位移越大,其倾斜程度也越大;竖向荷载较小时,桩身同时出现正负弯矩,竖向荷载较大时,桩身只有正弯矩或只有负弯矩;复合基础的破坏容易发生在防沉板与桩身顶端的连接处。研究内容和计算结果可为防沉板-桩复合基础的设计提供合理可靠的理论依据。

In order to study the force and deformation characteristics of the subsea mudmat-pile hybrid foundations under the vertical loads,a water project of 200 m depth in the South China Sea is taken as the research object,the mudmat-pile hybrid foundation is simplified as the form of mudmat and angle pile,the numerical calculation model of subsea mudmat-pile hybrid foundations is established by means of the numerical simulation software FLAC3D.The force and deformation characteristics of seabed soil,mudmat and pile body of mudmat-pile hybrid foundations under vertical loads are studied.The settlement of seabed soil,bending moment of mudmat,displacement and bending moment along the pile shaft under different vertical loads are compared and analyzed.The results indicate that the maximal positive and negative bending moments of anti-sinking plate appear in the middle of the anti-sinking plate and the joint between the anti-sinking plate and the top of pilerespectively.The larger the load,the greater the influence on the anti-sinking plate and the greater the role of pile in the mudmat-pile hybrid foundations.The horizontal displacement and the inclination along the pile shaft become larger with the increase of loads.The positive and negative bending moment along the pile shaft appear simultaneously when the vertical load is small.There is only positive bending moment or only negative bending moment along the pile shaft when the vertical load is large.The junctions between the mudmat and the top of piles of the mudmat-pile hybrid foundation are easily destroyed.The research results provide a reasonable and reliable theoretical basis for the design of the mudmat-pile hybrid foundations.