Experimental study on comparison of behavior between rigid pile composite foundation and composite pile foundation

Based on load distribution of raft foundation of high-rise buildings,it is suggested to arrange piles with a pattern where more piles are located near the center.Through reduced scale(1∶10) model test,the composite foundation and composite pile foundation were studied with the presence of model super structure.The studies include the raft settlement,subgrade settlement under pile bottom plane,ground settlement beside raft,reaction force distribution of soil and pile top,axis force and skin friction distribution of pile,and ratio of loads shared by pile and soil under raft.The behavior of composite foundation and composite pile foundation under working load condition were studied.Comparing with composite pile foundation,the experimental results showed that for composite foundation,the total settlement of subgrade is large,the different settlement of raft and the settlement of subgrade are small under pile bottom plane,the skin friction of pile is negative near pile top,and the soil shared more load than the pile.The composite foundation could make use of shallow layer subgrade bearing capability and composite pile foundation could make use of deep layer subgrade bearing capability.The conclusions of this paper may be useful for further theoretical studies and practical design.