Three-dimensional Non-linear Finite Element Analysis Of The Pile-Group Effect For Large-diameter And Super-long Pile-Group Foundation

The great-diameter and super-long pile group foundation is often adopted by large-bridge foundation at present. This kind of pile-group foundation have the characteristics of super-long,great-diameter,small-distance and large number, so the problem of pile-group effect is serious. But people's research and understanding of the pile-group foundation far behind the engineering practices. So, combined with the National Basis Research Program of China(973 program)-Basis Research on the Safety of Major Engineering Project in Hazardous Environmts(2002CB412707) and the Science and Technology Support Program of the Eleventh Fine Years Plane of China-the Key Techniques Study of the Construction of Sutong Bridge ( 2006BAG04B01 ,2006BAG04B05 ) ,and Jiangsu Provincial Traffic Science Study Program-the Key Techniques Study on Supersized boring pile-group foundation (04Y029) ,this paper take the pile-group foundation of Sutong Bridge as study example ,and study the problems of pile group effect for large pile group foundation with ABAQUS. The most works are as follows:(1) The research methods and actuality are deeply studied in this paper, and the constitutive model of soil and contact surface and the calculation theory of the non-linear finite element method are also expounded.(2) This paper compiles the Duncan-Chang constitutive model by using of the program of FORTRAN to redevelope the finite element program of ABAQUS, and tests the model.(3) The single pile is calculated by ABAQUS software. By comparison and analysis of the calculation result with the data of the self-balanced loading test, the reasonable mechanical parameters of pile group calculation is acquired with the direct back analysis methods.(4) For the pile group of different distance between piles and pile-number, this paper calculate the models by three-dimensional finite element methods, and the impact extend of the distance between piles and pile-number to pile-group effect are discussed and analyzed.(5) By combination with engineering example, this paper calculate and analysis the large pile group foundation of Sutong Bridge by three-dimensional non-linear finite element method. The load-transfer and settlement mechanism of great-diameter and super-long pile-group foundation is discussed in this paper, and the effect of the pile-group effect to pile-top load,pile stress,pile friction,pile-bottom load and pile-settlement is studied.