Pile-soil Interaction And Calculation Method Under Horizontal Load Of Large Diameter Pipe Pile

With the increasing demand for energy,the development of marine resources has developed from shallow-sea waters to deep-sea waters.Pile foundation is a common foundation form in marine engineering,and offshore pile foundation is often affected by horizontal load,which has an important impact on the safety of pile foundation.With the development of ocean engineering to deep sea area,the horizontal bearing capacity of foundation is required to be higher.In the analysis method of bearing capacity of horizontally loaded piles,p-y curve method is widely used in engineering.At present,the p-y curve(API selection)is based on the research results of small diameter piles.For large diameter pipe piles,the resistance characteristics are affected by the foundation size,which may be different from that of small diameter piles It has been debated whether the traditional p-y curve is suitable for large diameter horizontal piles.Therefore,in this paper,numerical calculation method is used to establish the three-dimensional finite element model of pipe piles with different length diameter ratios in heterogeneous soil with different stiffness under different friction conditions between the pile and soil.According to the finite element model,the p-y curve is studied.Based on this,the calculation formula of p-y curve under the influence of various factors is obtained and its failure mode is analyzed.The horizontal bearing capacity of single pile is calculated by elastic-plastic-mechanical equilibrium method and finite difference method.The specific research contents and results are as follows:(1)A three-dimensional numerical model for simulating the interaction between pile and soil of large diameter pipe piles was established,and the established model and analysis method were verified by centrifuge test data.(2)The finite element calculation of the horizontal bearing capacity of pipe piles with different length-to-diameter ratios was carried out.According to the finite element results,the deformation mode of the pile and the failure mode of the soil were determined,and finally the classification method and standard of the pipe pile were established.(3)In view of different aspect ratios,soil stiffness,soil strength,and interaction characteristics between soil and piles,a multi-factor orthogonal combination numerical calculation was carried out for large diameter pipe piles under horizontal load.The calculation method of ultimate bearing capacity and initial reaction modulus under the influence of the above factors was established,and finally a method for determining the p-y curve of large diameter pipe piles was proposed.(4)According to the results of numerical analysis,the failure mechanism of the large-diameter rigid pipe pile foundation was discussed,and the force analysis of the large-diameter pipe pile was carried out.Combined with the modified p-y curve calculation formula proposed in this paper,the calculation method of each force was proposed,and finally the analytical solution of the horizontal bearing capacity was established.Using the finite difference method,considering the classification of piles to modify the boundary conditions,the calculation program of the horizontal bearing capacity was compiled and verified.