Experimental Study On Bearing Capacity And Deformation Behavior Of Uplift Piles In Sand

With the rapid development of Chinese economy,city construction scale is becoming more and more big,the height of the building is increasing,the uplift pile has attracted more and more attention and been used in practical engineering,such as the foundation of the high-rise and super high-rise buildings,towers,offshore oil drilling platform and bridge building.However,the research on the uplift piles is based on the semi-empirical and semi-theoretical analysis,so it is urgent to study the bearing capacity and deformation behavior of uplift piles.In this paper,the indoor model test of single-pile is implemented,and the influence of the roughness of pile-soil interface and the ratio of pile-to-diameter ratio on displacement is discussed.The results show that the ultimate bearing capacity of the pile increases with the increase of the aspect ratio and the roughness of the pile surface,and the results also indicative that the ultimate bearing capacity of the pile is improved by the calculation of the theoretical model.The average friction value of the pile side also increases accordingly.Then indoor uplift model test of belled pile is carried out,the change of Q-S curve,the axial force of pile and pile side friction along the depth are discussed,the ultimate bearing capacity of belled pile is obtained,and the measured values of bearing capacity are compared with those of several theoretical models,The results show that the normative method can well predict the ultimate bearing capacity of the enlarged pile.Then,the indoor model test data of single pile and single pile with extended single pile are compared and analyzed.It is concluded that the displacement of the pile top,the ultimate bearing capacity,the pile bearing force,and the pile side friction resistance along the depth of the similarities and differences,The results show that the bearing capacity of the enlarged pile is higher than that of the equal section pile,and the average friction resistance of the pile is reduced.Finally,the experiment of indoor outburst of the piles with equal section is carried out.The influence of the ultimate bearing capacity of the uplift piles on the piles of the piles is discussed.On the top of the pile under uplift load,pile spacing,pile number S/D n of equal cross section of pile group pile effect of ultimate bearing capacity;and the pile group effect coefficient is discussed,the results show that the pile group effect coefficient with the increase of pile spacing increases,decreases with the increase of the number of the pile.