成层地基中倾斜受荷群桩的非线性有限元分析

针对轴、横向荷载共同作用或倾斜荷载作用下群桩基础受力问题的复杂性，引入无厚度型接触面单元和“无拉力”分析方法，采用非线性有限元法对倾斜受荷群桩的受力变形特性进行探讨，开发考虑材料非线性、桩-土-承台共同工作机理、桩周地基土体的分层性及不同桩项荷载形式等因素的计算程序，并由此讨论初始应力场及桩项荷载大小、倾角变化对桩身内弯矩与轴力分布的影响曲线。研究结果表明：刚性承台顶的荷载不变而倾角增大时，中桩桩项的弯矩逐渐增加，边桩的弯矩则逐渐减小；当荷载倾角不变而荷载增加时，承台下各基桩的弯矩变化规律则随荷载倾角的不同而变化。

Nonlinear finite element analysis of pile group under inclined loads in stratified subgrade

Considering the complex behavior of pile group foundation under simultaneous axial and lateral loads or inclined loads,no-thickness interface element(i.e.Goodman interface element) and no-tension force method were both introduced in the nonlinear element analysis of the inner forces and flexural deflection along the pile shaft under inclined loads.And a program was worked out as well,in which the material nonlinearity,pile-soil-pile cap interaction mechanism,stratified structure of the subsoil and various kinds of pile top loads were taken into account.Based on the present method and calculation program,influencing curves in the initial stress field,pile top loads and inclination angles on the distribution of moment and axial force along the pile shaft were discussed and obtained,respectively.The results show that,if the loads on stiff pile cap keep constant while the inclination angles increase,the bending moment of middle pile top and side pile top will increase and diminish,respectively.On the contrary,if the inclination angles keep constant while the loads increase,the bending moment of various piles under the stiff cap will change with the inclination angle and differ from each other.