Modification Of Numerical Manifold Method And Its Application In Earth And Rock-Fill Dam Analysis

In recent years, building large high earth and rock-fill dam is increasing, especially in the strong earthquake zones. So more scientific reasonable calculation method for earth and rock-fill dam engineering can discover the safety loophole, and also can provide more precisely gist for dam design. Numerical manifold method (NMM) is a new proposed numerical method which base on manifold method and finite cover technique. It has high calculation precision and can deal with continuum problems, discontinuous problems and block movement in a consistent way. Meanwhile, the calculation of earth and rock-fill dam engineering often includes discontinuous displacement calculation and simulation of block movement. So it is necessary that perform more rational simulation of earth and rock-fill dam engineering by NMM.This paper concentrates on the application and study of NMM in earth and rock-fill dam engineering. For introducing NMM into dam analysis, improvements of NMM are maded to solve dam static analysis problem, slope stability problem, collapse simulation problem, permanent displacement calculation problem, diaphragm wall stress analysis problem and permanent deformation analysis problem. The main contents of this paper are as follows:1. This article offer an introduction to the theory of NMM, and computational stability of NMM is studied. The E-B model and endochronic Model are introduced into NMM for considering material nonlinearity, and relevant calculation flow is given. Also, the hardening function in endochronic NMM is improved. These enable NMM can take geometrically nonlinear and material nonlinearity into account at the same time.2. We introduce the E-B NMM into the earth and rock-fill dam static stress analysis. The relevant program is developed. The results are compared with FEM. Considering the dam and diaphragm wall as discontinuous medium, the static stress analysis and the seismic dynamic response analysis are realized with endochronic NMM. The reason for crack at the crest after earthquake is analyzed. Finally, the3-D static analysis and seismic permanent deformation analysis of dam is done by endochronic NMM, and the maps of seismic permanent deformation are given.3. Base on the characteristic of NMM, the method that separating the destroyed element from the model is proposed for simulating the soil failure phenomenon, technological process of calculation is given. This method can compensate for the inefficiency of FEM in generating discontinuous deformation when simulating the shear test. It is applied into the simulation of direct shear test, relevant results are given. Uniting the gravity increase method, NMM is applied into slope stability analysis and slope collapse phenomenon simulation. The slope stability of dam is analyzed, and the influence of block boundary’s cohesion and frictional angle are discussed.Based on the above research, NMM is improved, and an integrated theory system for static, dynamic and slope stability analysis of dam with NMM is established. Provide a new way to analyze the stability of dam and slope.