水平荷载作用下PCC桩群桩效应数值分析

采用三维弹塑性有限元方法,研究了PCC桩群桩在水平荷载作用下的工作性状。比较了PCC桩群桩和等截面实心圆形桩群桩的水平承载力和群桩效率,得到了PCC桩纵、横向群桩效应的临界桩距;分析了桩距、桩数、桩顶约束条件对PCC桩群桩效率的影响。研究表明,PCC单桩和群桩的水平承载力都较等截面实心圆桩大;PCC桩纵、横向群桩效应的临界桩距分别约为外径的7.4倍和2.8倍;桩距愈小、桩数愈多,PCC桩群桩效率愈小,当设计桩距小于临界桩距时,应考虑群桩效应;PCC桩桩顶固接或铰接时,弯矩分布和承载力差异较大,设计中可以通过改变桩顶的约束条件来协调桩身受力性状。

Numerical Analysis of PCC Pile Group Effect under Lateral Load

The three-dimensional elastoplastic finite element method is adopted to study the behavior of laterally loaded PCC pile groups.Lateral bearing capacity and pile group efficiency of PCC pile are compared with equalarea solid circular pile.Critical pile spacing on group effect of PCC pile is obtained.The effects of pile spacing,number of piles,and restrained condition of pile top on PCC pile group efficiency are analyzed.The study results show that lateral bearing capacity of PCC single pile and PCC pile group are larger than that of equalarea solid circular pile.Longitudinal and transverse critical pile spacing on group effect of PCC pile group are 7.4 and 2.8 times of external diameter respectively.Pile group effect of PCC is more obvious with smaller pile spacing and larger number of piles.Pile group efficiency must be considered when pile spacing is less than the critical value.There is great difference in distribution of bending moment along PCC pile and lateral bearing capacity between fixed and articulated pile top.Behavior of PCC pile can also be coordinated by changing constraint condition of pile top.