Numerical Platform Of Elasto-plastic Finite Element Method And Its Application To Geological Engineering

Elasto-plastic problem is one of the most important problems in material nonlinearity. Elasto-plastic problem of geotechnical engineering has its own feature. There are hundreds of geotechnical constitutive models that have been proposed, but most of the constitutive models are just a mathematic representation and few can applied to engineering. How to establish a universal geotechnical elasto-plastic numerical analysis platform and numerical implementing some common constitutive models in order to settle practical geotechnical value problem are the priority research areas in this thesis.Structuring programming approach is adopted in traditional programming. It has many shortcomings such as limited expansion ability, low repeated usage of code, complex debug, and so on. Object orientation programming is one of the main modern programming methods. It has many merits such as encapsulation, succession, polymorphism, and so on and it can make the programming idea distinct, debug easily and high repeated usage of code. A universal geotechnical elasto-plastic numerical analysis platform and its constitutive model library is established and the numerical implementation and its application of geotechnical elasto-plastic constitutive model is studied comprehensively and systematically in this thesis by adopting the method of object orientation programming. The main research works are as follow:The beginning part establishes the base class of elasto-plastic numerical analysis by introducing data capsulation of object orientation method. Base on this work the geotechnical elasto-plastic numerical analysis platform was established and the altitude abstraction of the generality of all kinds of numerical analysis was finished. Chapter Two of the thesis studies some key problems in numerical implementation of elasto-plastic constitutive model, and deduces the numerical implementation style of Cam. model, Modified Cam. model, t_ij Clay model, t_ij Sand model and Lade-Duncan model.The third chapter establishes geotechnical elasto-plastic constitutive model library. Based on the model library, elastic and elasto-plastic constitutive model can be implemented by using few codes. Cam. model, Modified Cam. model, t_ij Clay model, t_ij Sand model and Lade-Duncan model were implemented in this thesis. The method and programming adopted in this thesis were certified by series comparisons between numerical examples and theoretical solutions.In Chapter Four, the elasto-plastic constitutive models mentioned above were applied to strip foundation, shield tunnel and foundation pit engineering. The parameter sensitivity of each constitutive model was analyzed and the main parameter and minor parameter directed different engineering problems of each model were get.In the final section comes the conclusion, which summarizes the whole thesis and points out its inadequacies that call for further studies.