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.