刚性桩复合地基工作性状的现场研究

In-situ Study of Working Property of Rigid Pile Composite Foundation

通过温福铁路瑞安试验段刚性桩复合地基的现场试验,对刚性桩复合地基处理软土地基的加固效果进行了系统研究,重点研究了单桩竖向承载力测试方法,"桩-桩帽"结构中桩与桩周土体受力状态,桩顶及桩间土压力分布规律,垫层的作用规律以及复合地基沉降随荷载时间的变化规律。试验表明:(1)桩帽-桩体结构的受力性状与单桩情况类似,设计中可不考虑桩帽下桩间土的作用;(2)桩土应力比随填高的增加而增加;(3)垫层对桩土应力比及地基沉降都有一定影响;(4)刚性桩复合地基总沉降量小,沉降稳定时间短,桩和桩间土存在沉降差。试验分析成果有助于刚性桩复合地基理论研究的深入,完善刚性桩复合地基的工作性状研究及优化工程设计。

The reinforcement effect of soft ground treated with rigid pile composite foundation was systematically studied through in-situ test of rigid pile composite foundation in Ruian test section on Wenzhou-Fuzhou railway.The research fo-cused on testing methods of single pile vertical capacity,stress state of piles and pile soil in “pile-pile cap”structure, pressure distribution law of pile top and earth among piles,the function law of cushion and change law of composite foundation settlement with load and time.The test results showed that:(1 )stress property of pile cap-pile structure is similar to that of single pile,so the function of the soil among piles under pile cap could be ignored in design,(2)pile-soil stress ratio increased with the height of filling.,(3 )cushion played a certain role in pile-soil stress ratio and foun-dation settlement,(4)total settlement of rigid pile composite foundation was very small and it could be stable in a very short time but there was settlement differences between piles and the soil among piles.At last,the results of the experi-ment contributed to study the rigid pile composite foundation theory in depth and perfect its working property research and optimization of the engineering design.