Research On Horizontal Bearing Characteristics Of Batter Pile Groups

The batter pile group foundation is a kind of commonly used foundation form for large structures,such as sea-crossing bridges,offshore oil drilling platforms and transmission towers.These structures are often subjected to horizontal loads,such as wave force and wind load,and these loads will be transmitted downward to the foundation.In engineering practice,there is still no systematic method for calculating the horizontal bearing capacity of batter pile groups.Therefore,model tests of batter piles were carried out.The finite element model was established by ABAQUS,and the p-y curve for batter pile was proposed.The p-y curve method calculation program of single pile and pile groups with batter pile was compiled by APDL in ANSYS.The main research contents and achievements include :(1)Model tests of batter piles were carried out.There were a total of five kinds of batter piles with differernt inclination angles.The graded horizontal load was applied to the pile foundation,and the internal force of each section is obtained by the strain gauge attached to the pile body.The horizontal displacement was measured at two heights above the mud surface,and the displacement and rotation angle of the pile body can be obtained according to the geometric relationship.The test results show that the horizontal bearing capacity of positive batter pile is larger than that of straight pile,and the horizontal bearing capacity of negative batter pile is lower.Under the same horizontal load,the bending moment,shear force and soil resistance of the negative batter pile are all larger than those of the straight pile,while those of the positive batter pile are smaller.(2)Based on the Hangzhou-Shaoxing Expressway(Hangzhou-Shaoxing)project,four horizontal test piles were tested in Hangzhou and Shaoxing respectively,and the horizontal bearing characteristics of straight piles was obtained.Based on the S1 test pile in Shaoxing,the finite element model was established in ABAQUS,and the straight pile was extended to the batter pile and the batter pile group pile foundation.The influence of inclination angle on the horizontal bearing performance of pile foundation was analyzed.(3)Based on the results of batter pile model test,the displacement and rotation angle of the pile at the mud surface were taken as the boundary conditions,and the pile displacement was obtained by integrating the bending moment of the pile twice.Combined with the distribution of soil resistance at the pile side under various loads,the p-y curves of positive batter pile,straight pile and negative batter pile at differe depths are obtained.Based on the hyperbolic p-y curve of straight pile and the p-y curve obtained by model test,the hyperbolic p-y curve suitable for batter pile foundation was proposed.(4)In ANSYS,the p-y curve method was used to calculate the horizontal bearing capacity of single pile and batter pile groups by setting nonlinear spring element on the pile side and using APDL programming.Taking the approach bridge foundation of Hangzhou Bay Cross-sea Railway Bridge as an example,the p-y curve method was calculated by using the program,and the calculation results of the p-y curve method of batter pile group were compared with those of the m method in the code.