水流荷载作用下海洋群桩受力特性研究

Study on stress characteristics of marine pile groups under the action of water flow load

为研究海洋群桩在水流荷载作用下的受力情况,通过计算流体力学(CFD)软件Fluent,采用大涡模型(LES)建立二维数值模型,分析了群桩中各桩的阻力系数和升力系数的时程曲线,以及桩周环向压力,并与单桩做对比.通过将计算结果对比及斯特劳哈尔数验证两种方法,验证了该模型的有效性.结果表明:群桩中的各桩存在着相互作用和影响,但前桩对后桩的影响远大于后桩对前桩的影响,主要表现在阻力、升力的峰值大小以及达到峰值的时间.前桩泄放的漩涡产生的低压区会对后桩的受力产生影响,使后桩阻力产生负值,升力大小也提高接近一倍;同时,群桩范围内流体的流速比外部低,导致群桩内外侧产生压力差,从而产生由内向外的压力.

In order to study the force of marine pile groups under the action of water flow,a two dimensional numerical model was established by Large Eddy Simulation(LES)numerical model and the Computational Fluid Dynamics(CFD)software of Fluent.This model was used to analyze the time history curve of resistance coefficient,lift coefficient and pile circumferential stress of each pile in pile groups.By comparison with experimental data and Strouhal Number,the effectiveness of the numerical model was verified with this method.The results show that piles from pile groups affect each other,while the influence of the front pile on the back one is much greater than the opposite.The effect is mainly reflected in the peak values of resistance coefficient and lift coefficient as well as the time to reach the peak.According to the research,the low pressure zone generated by vortex which is released from the front pile affects the force of the rear pile,which causes negative value of resistance of the rear pile.The value of lifting force is nearly doubled.Simultaneously,the flow velocity within the pile groups is lower than the outside surroundings.The different flow velocity leads to the pressure difference between the inside and outside of pile groups.Accordingly,pressure from inside to outside is produced.