Indoor Model Test Study on CFG Pile Composite Foundation

The effects of cushion thickness,pile length and pile spacing on the settlement and pile-soil stress ratio were studied by large indoor model test of CFG pile composite foundation.The results show that,various degrees of expanding diameter exist in CFG pile composite foundation,and the diameter expanded decreases in order from top down.The smaller is the thickness of cushion,the bigger is the sharing load of piles and the smaller load sharing ratio of soil among piles.The growth trend of the load borne by piles becomes very slow along with the increase of the cushion thickness.So it is advised to set the reasonable thickness of cushion to 20-30 cm in order to give full play to the load bearing role of piles.Pile-soil stress ratio increases with the increase of pile length and pile spacing under the circumstance of constant external load.Accordingly,in the pile spacing design of composite foundation,not only the bearing capacity of composite foundation must be ensured to meet the design requirements,but also the post-construction settlement of foundation soil must be ensured to satisfy the code requirements.Meanwhile,the negative influence of piling should also be taken into full consideration.