黏土地基上吸力式沉箱基础的三维破坏包络面研究

Three-Dimensional Failure Envelopes of Suction Caisson Foundation on Clay

作为新型的深水海洋基础形式,吸力式沉箱基础不仅要承受海洋平台结构及自身重量等竖向荷载的长期作用,而且往往承受波浪等所产生的水平荷载及力矩荷载分量,其承载特性是海洋工程结构设施建造与设计中的一个关键技术问题,但目前这种新型基础的工作性能评价与设计理论远远不能满足工程实践的需要。为此,本文以大型通用有限元分析软件ABAQU S为平台,数值实现基于位移控制的Sw ipe试验加载方法,分析了完全不排水条件下不同的水平荷载作用点吸力式沉箱基础的承载特性及V-H破坏包络面。同时,对完全不排水条件下吸力式沉箱基础在垂直上拔荷载V、水平荷载H和力矩M共同作用下的承载特性进行了三维有限元分析,数值实现了荷载-位移控制搜寻方法,确定了复合加载作用下吸力式沉箱基础的V-H-M三维破坏包络面。

As a newly developed type of foundation for deep water offshore and marine engineering, the suction caisson is usually subjected to combined loading of vertically uplift load, horizontal load and moment. To understand features of bearing capacity of suction caisson foundation is one of the key issues in design and construction of deep-water marine structures. However at present performance evaluation and design theory for such a new type of foundation can not sufficiently meet basic requirements of engineering practice. In this paper, the general-purpose finite element analysis package ABAQUS is employed to conduct three-dimensional numerical analyses on load-carrying features of suction caisson foundation under vertically uplift load V, horizontal load H and moment M. Then by the swipe test procedure of numerical value based displacement control, the ultimate bearing capacity of suction caisson foundation under monotonic load is evaluated. For the different point of action of horizontal loading, the features of bearing capacity and the V-H failure envelope of suction caisson foundation under fully undrained condition of subsoil are evaluated. Moreover, the V-H-M three-dimensional failure envelope of suction caisson foundation are established numerically by controlling load-displacement search procedure.