复合加载条件下吸力式沉箱基础承载特性数值分析

吸力式沉箱基础的承载特性是海洋工程结构设施建造与设计中的一个关键问题。这种新型的深水海洋基础型式,通常承受竖向上拔荷载与水平荷载的共同作用,其工作性能与设计理论远远不能满足工程实践的需要。本文采用有限元分析方法对吸力式沉箱基础的极限承载特性进行数值计算。以大型通用有限元分析软件ABAQUS为平台,通过二次开发,数值实现了Swipe试验加载方法和固定位移比分析方法,针对不同的沉箱长径比、土的强度折减系数,探讨了沉箱基础在垂直上拔荷载和水平荷载单调联合作用下的极限承载力,通过对不同荷载组合的数值计算构造了复合加载条件下沉箱基础破坏包络面。

Numerical analysis of bearing capacity behavior of suction caisson foundations under combined loading

As a new type of deep-water offshore foundations,suction caisson foundation is widely used in offshore engineering practice.The bearing capacity behaviour of this type of foundation under combined action of vertical pullout and horizontal force is one of the key issues in construction and design of offshore structures and facilities.However,the performance of such foundations has not been well understood and related evaluation and design method cannot meet the increasing requirement of engineering practice.Therefore a numerical procedure based on FEM for evaluating the bearing capacity behaviour of suction caisson foundation is developed in this paper.Based on the framework of the general-purpose finite element analysis software ABAQUS,both the Swipe test procedure of loading and the analysis method of fixed displacement ratio are numerically implemented.Then comparative numerical computations are performed for different combinations of the aspect ratio of caisson foundation and the reduction factor of strength of surrounding soils.The ultimate bearing capacity behaviour of caisson foundation under monotonically combined loads of vertical pullout and horizontal force is examined and the collapse envelope of caisson foundation is constituted for different combinations of vertical and horizontal components of loads.Such envelopes will be instructive in understanding the load-carrying behaviour of caisson foundations in ocean or offshore environment.