Numerical Simulation Of Strain Localization Of Rock Based On FLAC

As a mechanism of progressive failure, the problem of strain localization and shear band has attracted topic interest. Obtaining a full understanding of strain localization not only contributes to comprehension of mechanism of the natural hazards, but also has some extent significant to take precautions against the hazards. In chapter 1, some usual strain localization phenomena in nature, two kinds of mechanisms of strain localization and main methods to studying the phenomena, some progresses, the main principle of FLAG, strain softening constitutive relation, fields of application, reasons for simulating well strain localization as well as some successful examples concerned with strain localization have been introduced. In chapter 2, the influences of length of specimen, width of specimen and size of specimen on patterns of shear bands have been simulated in plane strain state. Larger specimen leads to larger inclination of shear band. Larger width of specimen causes the wider thickness of shear band and curved shear band. Larger size of specimen leads to brittle response of specimen. In chapter 3, the effects of length of specimen, confining pressure and loading rate on complete stress-strain curves have been modeled in tri-axial compressive tests or in plane strain state. Larger loading rate leads to larger inclination angle of shear band in the middle of specimen. In chapter 4, the influences of pore pressure on shear bands and on complete stress and strain curves have been modeled. Larger pore pressure causes larger inclination angle of shear band and no obvious shear band occurs. The effects of end constraint on shear bands, velocity fields and displacement fields have beenanalyzed in chapter 5. for stiff end constraint, the X form shear band occurs in the middle of specimen. Larger inclination angle of shear band is caused by larger rigidity of platen. In the next chapter, shear strain localization and volumetric strain localization of thick-walled hollow subjected to internal constant velocity have been investigated. In chapter 7, the seismic two blocks model and the seismic five blocks model have been modeled. For large normal and tangential rigidity, shear bands can penetrate old fault and propagate alone their inherent directions and the form of networks of shear bands is very apparent. Besides, many usual phenomena in realm of seismology and geology in chapter 7 can be seen from the results of seismic blocks model. In chapter 8, based on numerical simulation by FLAC-3D, the unified mechanism for natural hazards in geo-technical engineering involved in pore fluid has been proposed. Some main conclusions have been drawn in chapter 9.