Seminar

Rock deformation and fracturing occur at different scales. The two-dimensional grain-based model (GBM) is an advanced discrete element modeling approach, which is capable of explicitly simulating the micro-cracking behavior of crystalline rocks from the mineral scale. GBM treats the rock material as an assembly of deformable, breakable polygonal grains cemented along their adjoining sides. This study improves the conventional GBM from three aspects: incorporating (1) stochastic microstructures for monomineralic rock by thin-section examination and (2) realistic microstructures for polymineralic rock by digital image processing, and (3) the coupled thermo-mechanical mechanism, which reveals that the rock would be strengthened rather than weakened upon heating in the mild temperature range 25-200℃. The geological applications of the developed GBMs begin with the field characterization of fault damage zone, by uniaxial compression tests on rock specimens containing different configurations of en-echelon fractures, which are indicative of fault evolution. The mechanisms of en-echelon fractures evolution into macroscopic damage zones are revealed. Then, the stress-induced local fracturing processes under biaxial compression are quantified with respect to the location, moment and degree. This revolutionizes the numerical approach for examining the fracturing mechanisms involved in fault nucleation. Last, the seismic activity and its correlation with local stresses along sheared smeared fault interfaces are investigated, which generates valuable insight into the mechanisms of fault reactivation and seismic hazard migration. 

Zoom Meeting ID: 918 7088 2725

Additional information or password for Zoom: Ms. ZHANG Yahui, zhangeo@hku.hk