Experimental research on bearing behavior of composite foundation with rammed soil-cement tapered piles

Aimed at composite foundation with rammed cement-soil piles in soft ground,the contrast tests on a group of composite foundation with nine rammed cylindrical cement-soil piles and three groups of composite foundation with nine rammed tapered cement-soil piles were performed in laboratory,respectively.The average settlement difference among pile and soil,pile stress,average pile-soil stress ratio and the relationship between load and average settlement of four groups of composite foundation with rammed cement-soil piles were respectively studied under the same condition.The results indicate that the differential settlement between pile and soil can be adjusted by rammed tapered cement-soil pile,the ground settlement decreases and its bearing capacity is enhanced obviously.The bearing behavior of rammed tapered cement-soil piles in the composite foundation can be exerted by enhancing its taper.Within some load scopes,the average pile-soil stress ratio of composite foundation with rammed tapered cement-soil piles is higher than that of composite foundation with rammed cylindrical cement-soil piles.With the increase of load unceasingly,the load shared by tapered piles increases restrictedly,and the average pile-soil stress ratio of composite foundation with rammed cement-soil tapered piles is near a certain value or falls down,i.e.the slope skin of tapered pile can effectively alleviate the stress concentration of pile.