Numerical Analysis On Shear Bearing Capacity Of PHC Pipe Pile Under Different Shear Span Ratio And Axial Force

High strength prestressed concrete pipe pile is one of the most common pile foundations.Because of its low cost,good bearing capacity and convenient construction,it is often used in the foundation of high-rise buildings,ports,docks,transmission line towers,etc.When the pipe pile is in the soil,it not only bears the vertical pressure from the upper building,but also the bending moment and uplift force.For example,transmission line tower sometimes will be subjected to horizontal tension of the wire,which leads to bending moment at the base of the line tower,which makes the pile at different positions under different pressure or upward tension.The failure of the actual pile is also caused by the combination of horizontal and vertical forces.At present,the research on the bearing capacity of prestressed concrete pipe piles is mainly about the shear and bending performance under the axial pressure.No matter the test or simulation,most of the researches are carried out under the small axial pressure,and the research on the pipe pile as the anti pulling pile is less,so it is necessary to carry out the shear bearing performance of the pile under the larger axial tension and pressure Research.In this paper,the shear model of pipe pile under different axial forces and different shear span ratio is established by using ABAQUS finite element simulation software.The influence of different axial pressure,different axial tension and different shear span ratio on shear bearing capacity of pile is analyzed respectively.The conclusions are as follows:1.The smaller axial pressure can effectively improve the shear bearing performance of the pile.When the axial pressure increases to a certain extent,the cracking shear force and the ultimate shear force of the pile body begin to decrease,and the failure form of the pile body gradually changes from shear failure to small eccentric compression failure.Before the pile body cracks,the pile body is in the elastic stage,and the different axial forces have no influence on the performance of the pile.After the concrete cracks,the stress of the reinforcement increases obviously,and the axial pressure has little influence on the ultimate displacement of the pile.2.The existence of axial tension is not good for the shear bearing performance of pile body.With the increase of axial tension,the crack shear and ultimate shear force of pile body decrease constantly,and the failure form of pipe pile is gradually changed from shear failure to large eccentric compression failure.Before the pile body cracks,the different axial tension has no effect on the performance of the pile.The axial tension has a greater influence on the displacement of the pile when the ultimate failure occurs.3.With the increasing of shear span ratio,the crack value and limit value of shear bearing capacity of pile body decrease obviously,and the failure form is gradually changed from shear failure to bending failure with large eccentricity.The change of shear span ratio is approximately linear with the change of shear value.The larger the shear span ratio,the greater the displacement when the failure occurs.4.The stress state of the unit and the shear mechanism of the inclined section are analyzed.The ultimate bearing capacity of the pile body is affected by the influence of the normal stress of the unit,whether the axial force or the shear span ratio.5.The influence of different axial and shear span ratio on the bearing capacity of pile body is analyzed.The relationship between ultimate bearing capacity and shear span ratio of pile body is obtained under different axial forces.The shear span ratio of the pile has the same bearing performance under different axial forces.6.The curve of the bearing capacity of the pipe pile is drawn.When the axial pressure is0.4 times the design value of the compressive capacity of the pile body,the shear capacity of the pipe pile reaches the maximum value.The relationship between the bearing capacity of the pile and the shear span ratio and the axial force is presented,which provides a reference for further research.