复合加载情况下六自由度圆形基础失稳模式与 极限承载能力研究

海洋工程中结构物除了受到自身重力作用外，往往还受到海风、海浪、海流等的作用，使得海床土体中的基础一般受到集中力、弯矩和扭矩的联合作用，这一受力状态称为结构物基础的复合加载模式。详细研究复合加载模式下海床土体的失稳模式和极限承载能力，对海洋结构物的安全运行至关重要。以三维空间内圆形基础为研究对象，基于土体弹塑性极限平衡原理，利用非线性有限元分析软件ABAQUS，对空间六自由度圆形基础极限承载能力进行详细的数值分析。基于上述计算分析结果，揭示了单调加载情况下土体的失稳机理与极限承载能力，给出了复合加载模式下海床土体破坏包络面方程。给出的土体失稳模式和破坏包络面方程能够合理地评估复合加载模式下海床土体的极限承载能力。

Ultimate bearing capacity of circular footing with six-degree-of-freedom under combined loading

Some footings of ocean engineering structures are always to withstand their own vertical gravity loads and the horizontal loads induced by sea waves and current, which makes the foundation subjected to concentrated force, overturning loads and torque loads. The above loading state including vertical, horizontal and overturning moment loads is termed as combined loading. It is very necessary for the safety of ocean engineering structures to study the ultimate bearing capacity and failure mode of submarine seabed. By use of the finite element analysis software ABAQUS and the elastic-plastic limit equilibrium theory of soils, the ultimate bearing capacity of three-dimensional circular footing with six-degrees-of-freedom is analyzed. Based on the above numerical results, the failure mode and ultimate bearing capacity of seabed under monotonic loading are released, and reasonable failure envelopes for submarine soils under circular footing are given. The present failure mode and failure envelope can be employed to reasonably estimate the bearing capacity of three-dimensional footing under combined loading.