透水混凝土桩复合地基工作特性研究

Research on the Working Characteristics of Pervious Concrete Pile Composite Foundation

将透水混凝土桩(PCP)作为竖向增强体形成PCP复合地基,具有良好的工后沉降控制潜力。建立二维轴对称单桩有限元模型,将典型刚性桩复合地基的不透水竖向增强体按原尺寸置换为PCP。对比分析表明,上述置换不改变地基总沉降量且不削弱竖向增强体的应力集中程度。较不透水桩工况,PCP工况能够促进桩土沉降差与应力比的快速发展,更早发挥PCP的竖向增强体作用。原CFG、管桩和PCC工况在路面交工时刻的固结度分别为89%、93%、95%,而相应的PCP工况已完成固结。路堤平均堆载速率较大时,PCP复合地基固结效率提升作用更明显,工后沉降缩减效果更突出。将CFG工况改用PCP复合地基方案后,可将路堤平均填筑时间由1 060 d缩减至7~30 d,在堆载完成时刻固结度可超过95%,且工后沉降小于5.0 mm。PCP复合地基为软基地区工程控制工后沉降、缩短建设工期提供了新的地基处理技术选择。

The pervious concrete piles(PCP)is used as vertical reinforcement to form a PCP composite foundation showing good potential for post-construction settlement control.A 2D axisymmetric single pile finite element model is established,and the impervious vertical reinforcement of a typical rigid pile composite foundation is replaced with PCP of the original size.Comparative analysis shows that the above replacement does not change the final total settlement of the foundation and does not weaken the stress concentration of the vertical reinforcement.Compared to the impervious pile condition,the PCP condition can promote the rapid development of pile-soil settlement difference and stress ratio,and can exert the vertical reinforcement effect of PCP earlier.The consolidation degree of the original CFG,pipe-pile,and PCC conditions at the time of road completion are 89%,93%,and 95%,respectively,while the corresponding PCP condition has completed consolidation.When the average embankment loading rate is high,the consolidation efficiency of the PCP composite foundation is more significant,and the post-construction settlement reduction effect is more prominent.By using the PCP composite foundation replacing the CFG condition,the average embankment construction time can be reduced from 1060 days to 7-30 days,and the consolidation degree can exceed 95%at the completion of embankment loading,with a post-construction settlement of less than 5.0 mm.PCP composite foundation provides a new foundation treatment technology option for controlling post-construction settlement and shortening construction period in soft ground engineering.