Model Test And Numerical Analysis Of Bearing And Deformation Behavior Of Batter Piles Under Uplift Load

Not only vertical displacement,but also horizontal displacement will be induced for the batter pile under uplift force,which is different with the straight pile.the cross section of the batter pile not only have the existence of axial force,but also have the bending moment and shear force,which makes the behavior of inclined pile is much more complicated than the straight pile.At present,there is a lack of reasonable design method of the inclined pile at home and abroad,but the design method of straight pile is often used in engineering practice.the failure form of straight pile is relatively simple,so the straight pile design principle does not reflect the inclined pile in the destruction of the complex stress characters.In summary,the study of the action of inclined pile under the vertical load lay a certain theoretical basis for the design of the inclined pile and practical engineering applications.Firstly,the influence of the length diameter ratio and inclination angle on the bearing capacity and internal force transfer mechanism of inclined piles is studied by means of model test,and compared with the straight pile uplift behaviors.The results show that the uplift displacement of the inclined pile is greater than that of the corresponding vertical pile under the vertical uplift load of pile,and the larger the inclination angle,the larger the vertical displacement;The larger the inclination angle of the pile,the larger the uplift displacement and the larger the bearing capacity.The axial force of the inclined pile body is greater than the axial force of the corresponding straight pile,the larger the inclination angle,the faster the axial force decreases along the depth,the greater the length to diameter ratio,and the slower the axial force decreases along the depth.There is a moment in the section of the upper section of the inclined pile body,and the maximum value of the bending moment of the inclined pile appears in the section of relative depth z/L=0.14,no matter how many are the uplift load,the inclination of the pile body and the ratio of length to diameter.with the same pulled load,The influence of the length diameter ratio on the maximum bending moment of the inclined pile is very small;when the length diameter ratio of the oblique pile increases,the maximum bending moment of pile becomes smaller;The bigger inclination angle,the bigger the maximum average side friction resistance of pile,The maximum average frictional resistance of inclined piles is between 0.2 and 0.4 of the relative depth of the pile on the sand surface,In addition,the upper part of the pile has a negative average friction phenomenon.Then,the influence of the angle of the pile body and the ratio of length to diameter of the pile is analyzed by the finite element software ABAQUS.The numerical simulation display that the ultimate pullout capacity of uplift piles increases with the increase of the ratio of length to diameter.When the length diameter ratio of the pile is small,the influence of the increase of the inclination angle on the ultimate bearing capacity is small.When the length is relatively large,the influence of the inclination of the pile on the ultimate bearing capacity increases gradually.Based on the same ratio of length to diameter,when the angle is less than 10°,with the increase of the dip angle,the inclined pile bearing capacity also increased gradually.