分层土中支盘桩水平承载特性模型试验研究

MODEL TEST STUDY ON HORIZONTAL BEARING PERFORMANCE OF BRANCH PILE IN LAYERED SOIL

制作支盘桩单桩和群桩模型试验装置,对处于分层土和均质土中的单桩和群桩基础进行室内水平静载荷模型试验,分析土层性质和承力扩大盘位置对桩水平承载特征的影响。结果表明上层土的性质对支盘桩水平位移、桩身弯矩和桩侧土压力的影响明显,特别是对扩大盘靠近桩身上部的单桩,上层土加固能显著降低桩顶的水平位移,提高桩的水平承载力;对支盘桩群桩基础,扩大盘所处的上层土较软弱时,群桩效应明显;上部土层加固后群桩效应减弱,各基桩近似独立工作,再加上承台对桩顶的固接约束作用,桩身弯矩和桩侧土压力均显著减小。

Models were made for single and group branch pile tests,to carry out test the indoor horizontal static load model test for single and group pile foundation in layered soil and homogeneous soil and to analyze the influence of soil property and bearing capacity enlarging branch position on horizontal bearing characteristics of the pile.The results showed properties of upper soil has more obvious influence on horizontal displacement of branch pile,bending moment of pile body and side soil pressure.For the single pile with extended plate near pile top,the reinforcement of upper soil layer could decrease the horizontal displacement and increase the horizontal bearing capacity significantly.For group branch pile foundation,the effect of group piles is more obvious when the upper soil layer is weak at the extended plate;when upper layer was reinforced,the effect of group piles decreases and single pile in group piles works independently similar to single pile.But the restraint effect of pile cap causes obvious reduction of bending moment of pile body and side soil pressure.