Experimental Study On Bearing Characteristics Of Tapered Pipe Piles

Based on the comparative analysis of the advantages and disadvantages of prestressed concrete pipe piles and wedge piles,the research team proposed a new pile foundation-wedge pipe pile.In this paper,the working mode of the wedge-shaped pipe pile is studied by the combination of model test and numerical simulation.The main research work includes:(1)Based on the indoor model test,the load-settlement law of equal-section pipe piles,wedge-shaped pipe piles and wedge-shaped piles are obtained.By comparing and analyzing the load-settlement curves of the four model piles,the effects of pile foundation structure,wedge angle variation and material dosage on load-sedimentation law,ultimate bearing capacity and load transfer law are obtained.(2)Based on the study of model pile-soil interaction,the influencing factors of pile-soil interaction are analyzed.From three aspects: the consolidation age,the roughness of the contact surface,and the influence of the interface normal stress on the shear strength.Based on the summary analysis of the test results,it provides a reference for numerical simulation analysis.(3)Based on the ADINA finite element software,the model test was numerically simulated,and the indoor model test results were compared with the numerical simulation results to verify the reliability of the numerical model.On this basis,the influencing factors of the model piles are studied by the finite element software system,and the influence law of the wedge piles on the foundation soil is obtained.According to the experimental research,the following conclusions are drawn:1.Under the same average diameter condition,the soil plug of the concrete wedge pipe pile reaches the soil plug occlusion state in the earlier case;the wedge pipe pile with the smaller diameter of the pile end under the same wedge angle condition,the final The smaller the height of the soil plug is;the wedge angle of the wedge-shaped pipe pile is increased under the condition of the same pile end diameter,and the height of the soil plug is finally increased.2.The change of structural form can significantly change the trend of load-settlement curve.The ultimate bearing capacity of wedge-shaped pipe pile is larger.Increasing the wedge angle can significantly increase the bearing capacity.Increasing the amount of material does not increase its ultimate bearing capacity.3.Under the action of low normal stress,the roughness of the contact surface increases,and the damage of the contacted soil is greater with the increase of the shear displacement,and there is a significant softening phenomenon;when the normal stress increases significantly,The influence of normal stress on shear displacement is gradually increased,which weakens the influence of the roughness of the contact surface on the change of shear displacement curve to some extent.