多向荷载耦合作用下复合基础承载特性分析

Analysis of bearing behavior of composite foundation under multidirectional combined loads

针对水下石油生产系统复合基础在不同方向荷载耦合作用下的承载特性,分析复合加载模式下的破坏包络线。采用非线性有限元数值模拟方法,通过固定位移比法绘制竖向—倾覆、水平—扭转、竖向—水平—倾覆、竖向—水平—扭转荷载空间内的地基承载力破坏包络线,分析不同长径比和桩间距对不同方向荷载耦合作用下地基承载力包络线的影响,并分别将归一化处理后的竖向—倾覆、水平—扭转荷载包络线拟合为关于长径比和桩间距的包络线数学表达式。结果表明:随竖向荷载分量的增大,基础在二维荷载空间内包络线尺寸有所减小。结合实际工程应用,通过绘制地基承载力破坏包络线,对基础设计方案校核和评估,能很好指导工程实践与设计。

In order to study the bearing characteristics of the composite foundation of the subsea oil production system under the coupling of loads in different directions,the failure envelope under the composite loading mode was analyzed.The nonlinear finite element numerial simulation method was used for the simulation.The failure envelopes of foundation bearing capacity in two-dimensional and three-dimensional load spaces were drawn by the fixed displacement ratio method,and the influence of different length-to-diameter ratios and pile spacing on the bearing capacity envelopes under the coupling of loads in different directions was analyzed.The results show that with the increase of the vertical load component,the size of the envelope of the foundation in the two-dimensional load space decreases.Combined with actual engineering application examples,by drawing the failure envelope of the foundation bearing capacity,the foundation design scheme is checked and evaluated,which is a good guide for engineering practice and design.