ABSTRACT:

In this paper, the evolution of damage and fracture in jointed rocks or concrete is presented as the main form of failure of engineering structures. Based on the frame of elasto-plastic theorem, the problem of the localization is analyzed by the authors from the discontinuous bifurcation point of view. By spectral analysis of eigenvalue of the bifurcation equations, a method for structures failure is presented. According to theoretical results, the numerical simulation of the collapse and the capacity of dams can be implemented. A super large arch dam in China, Ertan Arch Dam, serves as an example of the numerical simulation of the failure process and the capacity. The results illustrated in this paper from the numerical simulation are approximately consistent with that of physical tests.

1.
INTRODUCTION

The problem of stability for arch dam abutment is acquiring vital importance in the design of arch dams, since the size of arch dams are getting higher and wider and the quality of the foundations of those dams seems to be more deficient for dam construction. The problem is still a great challenge to the knowledge of engineers, because it is extremely complicated to analyze the failure mechanism of rock abutments. In this paper, a numerical simulation to the failure of dam is presented. It consists of analyzing the process of dam failure on which stability of arch dams evaluation is based. The key point of simulation of failures in dam is to implement localization and bifurcation analysis of concrete-rock materials and stability analysis of dam structures. Both failure models of softening state in materials and structures were studied, and their constitutive relations are used to analyze the crack propagation process. The constitutive relations of jointed rock mass and their strength models are, so far the main subjects focused. It is well known that when the failure of rock abutment occurs, there are, always many brittle cracks to be found in the rock mass. The Malpassat Dam accident was attributed to the rock cracks propagation. The Collabrain Dam had cracked with three major fractures in the dam body. It is necessary to apply fracture mechanics for the arch dam. In this paper, the analysis to jointed rack is given, and a fracture mechanics model, used in finite element method is proposed. The bifurcation and softening models have been applied to calculate the failure state for dam bodies and rock abutments.

2.
NONLINEAR NUMERICAL SIMULATION ANALYSIS OR DAM FAILURE AND DAM BEARING CAPACITY

To make the problem clearer, a flow chart for nonlinear numerical simulation analysis is presented in Fig.l First of all, two items should be discussed below:

2.1
Constitutive Formulation of Plasticity and Bifurcation Characteristics

A lot of work has been devoted to the abrupt changes in the deformation field that occur in elastic-plastic bodies across narrow zones and shear bands. Bifurcation is occurring in relation to the rate of deformation gradient, and also velocity rate.

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