The Research And Application On The Efficient And Local Decrease Accuracy Method In Underground Engineering

In recent years, with worldwide energy shortage and the floor space decreasing, underground engineering has been greatly developed. Finite element method is the main method of numerical analysis in underground engineering, develop well is most widely used.However, while finite element method is being used in underground engineering calculations, it has certain deficiencies. Underground structure is composed of several different soil materials, and has very complex structure and composition. Using finite element method mesh geotechnical structure, as the complex forming of the soil, making mesh will be a very difficult work. For addressing the complexities and difficulties of mesh, we have to change the core algorithm of finite element method, and make mesh simplify, this is the efficient and local decrease accuracy method.This paper details the basic principles of finite element method and the specific methods and steps of finite element method for structural calculation. Then researches on the core algorithm of finite element method, according to Saint-Venant principle,introduct the concept of composite element,proves that if the element is composite element,the original integration is still able to be calculated. Based on the feature that numerical integration solution is in fact that the Gaussian integration points are calculated,we endow element internal with different material property values according to the different location in internal element artificially.This is the efficient and local decrease accuracy method. Elaborates theoretical basis of the method, explain its advantages and limitations, and proposes ways to resolve its limitations; details concrete measures and steps of using the method for structural analysis, and uses the method to code computer program. The method is able to simplify the work of mesh generation,improve the overall computing efficiency,is especially suitable for underground engineering,and we can quickly get the overall characteristics of the structure that we are most concerned about. Finally builds the actual examples of underground engineering, uses the finite element software Ansys and the efficient and local decrease accuracy method program to calculate the actual examples, compares the results between them,gives further evidence of the feasibility of the method...