针对锚线斜拉作用下吸力筒与砂土相互作用的微观特征仍不清楚这一问题,采用离散元(discrete element method,简称DEM)-有限元(finite element method,简称FEM)耦合数值方法,从宏观到微观角度分析系泊点深度对吸力筒基础抗拔性能的影响.在建模中,采用FEM中有限元网格来模拟吸力筒,采用DEM中颗粒来模拟吸力筒周围砂土,并通过控制滚轴运动来模拟锚线的拉作用.结果表明:吸力筒的拉力-位移曲线存在峰值拉力,且与不同系泊点深度下吸力筒运动模式有密切关系;吸力筒旋转方向、拔出位移的反转临界系泊深度点位于吸力筒从顶部往下h=66.7％深度附近(即吸力筒深度的2/3处,h为系泊深度).此外,从颗粒尺度分析了土体变形及破坏行为,最终确定了吸力筒-颗粒土相互作用的破坏模式.研究结果表明,忽略锚线的系泊点深度将会导致误判吸力筒的承载能力及与土体的破坏模式.
Numerical simulation of the uplift capacity of suction caisson foundation in sandy soil:effects of mooring depth
The micro-mechanisms of suction caisson-soil interaction under the action of inclined mooring lines remain unclear.In this study,a coupled discrete element method(DEM)and finite element method(FEM)was adopted to investigate this issue from macro-to micro-scales,with a focus on the influence of mooring depth.The sand particles were simulated by DEM,and the suction caisson was simulated by FEM.The mooring line tension was simulated by controlling the roller motion.The results revealed that the differences in the evolution of the force-displacement curves were attributed to the differences in the suction caisson motion modes at different mooring depths.The mooring depth differences caused significant differences in the vertical pull-out displacement,rotation angle,and deformation of the suction caisson.The critical reverse mooring depth point of suction caisson rotation direction and pull-out displacement is located near the depth of h=66.7％from the top of the suction caisson(i.e.,2/3 of the suction caisson depth).Moreover,the deformation behavior of the soil was analyzed at the scale of particles,ultimately determining the failure mode of the interaction between the suction caisson and the particle soil.The study showed that neglecting the mooring depth of the mooring line may lead to a misjudgment of the bearing capacity of the suction caisson and the failure mode of the soil.
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