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

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 focused on testing methods of single pile vertical capacity,stress state of piles and pile soil in pile-pile capstructure,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) pilesoil stress ratio increased with the height of filling.,(3) cushion played a certain role in pile-soil stress ratio and foundation 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 experiment contributed to study the rigid pile composite foundation theory in depth and perfect its working property research and optimization of the engineering design.