Boundary Element Method In Plate Raft Foundation Analysis

This article uses foundation layered elastic modle which is analogy to the real project, deduces and solves the plate by boundary element method(BEM) and summing in layers method. When calculating it,the foundation effectness is taken in the controlling differential equation of thick-plate on the elastic foundation, general First the base solveness of the equation is derived by Flouier integeral and 8 -function.,then the boundary integeral equation is created by image work theory,Finally discret the boundary and the algebraic equation iscreated. solved it ,the displacement and internal forces of thick-plate is obtained. Ther are three methos in calculating the foundation stiffness matrix by puting force on the element whether it is concentrated force or distributed force.In this article the near-distributedand far-concentrated is adopted.Some documents show that the proposed method in calculating stiffness matrix is satisfied in solving the displacements and internal forces of plate by elastic theory.The BEM as a valuable method has great advantage over precision and discret;the foundation layered elastic modle has specific physic mean and easy calculatness. It is proved that the proposed method takes great advantage over clculateness precision and convergence.The interaction of upper structure ,base and ground is touched in this article.After calculating upper-structure by sub-structure method,and the equentitive load and stiffness matrix is derived,then the displacements and internal forces of thick-plate is obtained as the foundation is treated. The solution show that the upper structure reduces the internal forces of plate.