ABSTRACT:

Numerical Manifold Method(NMM) has the characteristics of simulating the processes of deformation, damage or crack propagation, quasi-static and dynamic development, and the processes are the gradually accumulating, developing and incrementally loading processes. Based on fundamental theory of numerical manifold method(NMM),the increment theory and equilibrium equation of NMM, considering damage analysis for rock mass, are set up, and the processes of deformation and slip are simulated for some slope with circular sliding face.

I.
INTRODUCTION

With the development of static and quasi-static process in rock mass engineering, rock mass system spontaneously forms a state in good time-space order, or reaches new equilibrium, or unequilibrium and non-linear phenomenon. This un-equilibrium leads the system to dynamic development. Moreover, the deformation and the damage of rock mass are controlled by rock mass structures (Gu,1979). Different rock mass structures have different mechanical behaviors. In the same system, there are many kinds of possible rock mass structures, so rock mass is a mixture with continuous and discontinuous mediums. Owing to a long-term action of engineering geomechanics, all kinds of discontinuousplanes are joined up each other, and the potential interface of whole losing stability is formed. For the situation, there is a trend of dynamic development, and there is also a coupling material or continuous and discontinuous mediums. The NMM developed by G. H Shi in 90's uses finite cover technique and takes in advantages of finite element method (FEM) and discontinuous deformation analysis (DDA). Total displacement function in the NMM is formed by the cover displacement functions, so mechanical problems of continuous and discontinuous deformation are integrated in the method. It is able to solve the intersection problems of dynamics with statics and the couple problem of continuous with discontinuous mediums. It may be seen from present published references (Shi.,1996: Chiou,1997: Wang.Z.1997: Wang.S.1997) that the damage analysis of rock mass is not dealt with in the NMM, and the theory and equations are full quantitative form, which are not identical with the deforming process of rock mass and the increment load and unload at stage construction. In this paper all kinds or imperfections of rock masses, such as micro-cracks, micro-crevices and pores, are regarded as initial damage. The increment theory of considering the damage of rock material in NMM is set up using the basic theory of NMM, and relative calculating formulas are derived. The treating ways of distributive forces and fixed points in accordance with geotechnical engineering, are reasonably improved. Finally, an applied calculation example is given.

2.
DISPLACEMENT,STRAIN AND STRESS

Total displacement function is formed by cover functions on physical covers in the NMM.

3.
INCREMENT EQUILIBRIUM EQUATION OF NMM

When external environment, construction or load condition have a certain influence upon the complex rock system, the structures of rock masses produce deformation and failure, and the structural planes in rock masses itself also bring about deformation and slide. The forces accompanied by the deformation.

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