| The deformation localization of the rock is both an important characteristic of the rock material's instability and the symptom of material failure, which directly leads to the decrease in its overall intensity during the loading process and the loading-bearing capacity of the rock project.Therefore, the study and prediction of the initiation and evolution of the deformation localization band and the evolution rule of the shear band are very meaningful to the exploration of the rock material's instability and failure. In this paper, applying the methods of theoretical study and experimental study as well as numerical analysis, from a new point of view, the author makes a thorough and systematic study of the soft rock's deformation localization from its initiation, evolution, and taking shape into macro-shearing band and its instability as well, and yields some positive research results.(1) Through the experimental study of red mud sand rock in Chongqing under the conditions of uniaxial and triaxial loading, the author analyzes the damage evolution law of the soft rock and the nonlinear fractal features of the crack expansion. On such a basis, the author, combing the probability distribution hypothesis of the rock strength, studies the critical phenomenon during the process of the rock's unstable failure with the adoption of renormalization model, and gains the theoretical critical point of the rock material's unstable failure and the development direction of its stability. Contrasting the experimental data with the calculative results of renormalization model, the author proves that the model can accurately simulate the rock's unstable failure and effectively predict the critical point of failure, thus, establishes the criterion of the rock's stability.(2) According to the deformation localization of the rock and the self-organized critical action during the instability failure process, "sandpile cellular automata" model is adopted to study the microscopic self-organized critical behavior such as the crack expansion and damage evolution and energy release during the rock deformation process.(3) A plane strain loading system is developed, then the localized deformation and the instable failure mechanism of Chongqing red mud sandstone under the plane strain condition are investigated by this loading system for the first time. Author studies the elastic wave features during the plane strain loading process, keeps track of the whole evolution process of the rock's deformation localization, and acquires the initiativepoint of the soft rock's deformation localization and the critical point of instable failure. Meanwhile, he studies, under the condition of plane strain, the affection of the initiation and evolution of the soft rock's deformation localization according to the variations of loading speed, water content and slope angle.(4) Adopting advanced laser digital speckle method, the author first conducts the contrasting experiments of deformation localization between the mud sandstone and muddy rock and studies the effects of loading speed on the soft rock's deformation localization under uniaxial pressure. Through a range of correlation analyses of speckle interference, and the temporal and quantitative pursuit and determination of the variation laws of the soft rock's deformation localization, he observes the whole "revolving" process of the deformation localization area of the mud sandstone and the muddy rock. Also, he determines the starting moment of localization and quantitatively surveys the width and the deformation speed of the localization area.(5) Based on elastic-plastic constitutive model of the rocks, the author, adopting the sliding block - spring combination system, studies the mechanics model of the shear band and obtains the starting conditions of deformation localization controlled by such a mechanics model.(6) According to the bifurcation theory of material instable failure, the author makes a theoretical study of the soft rock's deformation localization in order to d...
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