Comparison and analysis between long-short-pile pile foundation and other types of foundations

Three dimensional elastoplastic finite element method is adopted to analyze various types of foundations,which include short pile foundation,long pile foundation,long-short-pile composite foundation and long-short-pile pile foundation.Elastic thin plate theory is applied for research of raft,and Mohr-Coulomb elastoplastic model and linear elastic model for soil and piles respectively.Interface between pile and soil is simulated by nonlinear spring model.Comparative contents aim at settlement behavior and allocation of load at top of piles and axial force in long piles or short piles.The results showed that the average settlement of long-short-pile pile foundation is less than that of the whole short pile foundation and long-short-pile composite foundation,but larger than the whole long pile foundation.The neutral points of long piles lie deeper and suspend larger negative friction force in long-short-pile pile foundation than that in long-shortpile composite foundation.The role of short pile in long-short-pile pile foundation is more effective than that in long-short-pile composite foundation,but the maximum axial force of long piles is less than that in long-short-pile composite foundation.