密实砂中刚性锚桩斜向抗拔承载特性

Oblique Uplift Bearing Characteristics of Rigid Anchor Piles in Dense Sand

刚性锚桩作为海洋结构系泊系统重要基础形式之一,常承受斜向拉拔荷载作用,其斜向抗拔承载机理相对柔性桩要更为复杂。通过数值模拟和理论分析,针对加载方式、桩土界面摩擦系数对锚桩斜向抗拔承载力的影响展开研究。基于有限元数值模型,获得不同加载方式、摩擦系数的锚桩破坏包络面,发现锚桩斜向抗拔承载力受加载方式影响较为明显;受Mohr-Coulomb模型的局限,数值模型较难准确模拟粗糙锚桩的竖向抗拔承载行为;随着摩擦系数的增大,锚桩竖向抗拔承载力会因破裂面向桩周土内部发展而增大;基于桩侧土抗力反“S”形分布假设计算所得的锚桩水平向承载力相对准确。最终建立了考虑桩土界面摩擦系数的刚性锚桩斜向抗拔破坏包络面模型。

As one of the important foundation types of mooring systems in marine structures,rigid anchor piles often bear oblique upward pulling loads,and the mechanism of oblique uplift resistance is more complex than that of flexible piles.Through numerical simulations and theoretical analysis,the influence of loading modes and pile-soil interface friction coefficients on the oblique uplift capacity of anchor piles was studied.Based on the finite element numerical model,the failure envelope surfaces of anchor piles in different loading modes and friction coefficients were obtained,and it was found that the oblique uplift capacity of anchor piles was significantly influenced by loading modes.Due to the limitation of Mohr-Coulomb Constitutive Model,it was difficult for numerical models to accurately simulate the vertical uplift properties of anchor piles with rough appearances.With the increase of friction coefficients,the vertical uplift capacity of anchor piles increased because of the development of fracture toward soil around piles.The horizontal bearing capacity of anchor piles was relatively accurate calculated by the S-shaped distribution hypothesis of soil resistance.Finally,an envelope model of rigid anchor piles was constructed considering the friction coefficients of pile-soil interfaces.