| Pile foundation in high-intensity areas is vulnerable to large horizontal and vertical forces under seismic action,while prestressed concrete pipe piles are limited in areas with seismic fortification intensity of 8 degrees and above due to their poor shear capacity.The reinforcement ratio of conventional prestressed concrete solid square pile along the depth direction of soil does not change,but in practical engineering,the pile interacts with soil,and the pile body is subjected to non-uniform stress,that is,the bending moment and shear force of the pile body in a certain range below the soil is larger,and the horizontal force is smaller when it exceeds a certain range.Therefore,it can be considered to reduce the configuration of prestressed reinforcement at the bottom of the pile.In this paper,a kind of prestressed concrete solid square pile suitable for promotion in high-intensity areas is proposed.The upper part of the pile adopts the prestressed concrete square pile with high reinforcement ratio,and the lower part adopts the prestressed concrete square pile with low reinforcement ratio.The connection joint part adopts the mechanical connection to form prestressed composite piles with different reinforcement ratios.In this paper,the mechanical properties of different reinforced prestressed concrete square piles and mechanical connection joints are studied by experimental and numerical simulation methods.The bending and shear tests of two kinds of prestressed concrete square piles with different reinforcements were carried out,and the bending test of the mechanical connection joint was carried out.The horizontal bearing capacity of prestressed composite piles with different reinforcements considering pile-soil interaction is analyzed by numerical simulation.The feasibility of the prestressed composite piles with different reinforcements is verified.The main research work and conclusions are as follows:(1)The basic mechanical properties of the material are determined through the material test of concrete,prestressed spiral groove steel bar and the mechanical connection joint,which provides the basic parameters for the subsequent ABAQUS finite element analysis.(2)Through the bending and shear performance tests of two prestressed concrete square piles with different reinforcements,the cracking load,deformation performance,ultimate bearing capacity and failure characteristics are obtained.The two prestressed concrete square piles with different reinforcements are connected by the mechanical connection joint,and the bending performance test of the joint is carried out to study the bending bearing capacity of the joint.(3)Through the ABAQUS finite element simulation of the mechanical properties of prestressed concrete square piles with two different reinforcement ratios in(2),the finite element analysis results are compared with the experimental results,and the accuracy of the simulation results is analyzed.On this basis,in view of the fact that the influence of axial pressure on the bending performance is not considered in the bending test,the numerical models of piles under different axial compression ratios are established in the finite element model to study the bearing capacity of piles under different axial compression ratios.Considering only one shear span ratio in the shear test,the numerical model of pile under different shear span ratio is established in the finite element model to study the bearing capacity of pile under different shear span ratio.(4)ABAQUS is used to establish the numerical model of prestressed composite piles with different reinforcements in the upper and lower parts of the pile.The geological survey data of a building site in Suqian City,Jiangsu Province are selected to analyze the horizontal bearing capacity of prestressed composite piles with different reinforcements considering pile-soil interaction.The parameters under different soil layers,pile length,vertical load and bending moment load are analyzed to demonstrate the feasibility of this prestressed composite pile with different reinforcements,and the steel consumption and engineering cost saved by this type of pile are briefly analyzed. |
