modeling horizontal insitu stress with flac3d

Increasing the detonation timing between blast-holes induces more damage into the rock mass and fragmentation in the burden. Increase in rock heterogeneity, above a threshold, induces more fractures. Removing the in-situ stresses results in smoother sidewall fracturing with more damage in the crown and invert. Due to the combined effect of the free surfaces provided by the adjacent blast-holes and the maximum principal stress induced by in-situ stresses, the fractures at the lower part of the tunnel sidewalls have the tendency to propagate upwards with a diagonal direction about 60° relative to vertical, in accordance with the field test results. Smoother surfaces are created at the crown and invert by the propagation of long fractures in the horizontal direction. Later, these fractures coalesce into larger cracks, which prevents the formation of smooth tunnel walls and increases the EDZ. The model simulates the stress state around vertical and inclined wellbore when a formation. models in a software pro gram called FLAC3D. For the contour blasting under high horizontal in-situ stresses, blasting-induced fractures initially propagate horizontally, even though the holes are decoupled. direction of the maximum horizontal in-situ stress. The combination of in-situ stress field, equation-of-state based blast loading, fracturing in tension and shear with gas flow loading of fractures enables the modelling of complex dynamic interactions from multiple blast rounds. A combined finite-discrete element method (FDEM) parallelized on the basis of GPGPU is implemented to model the rock fracture and fragmentation process and the resultant excavation damaged zone (EDZ) development induced by the controlled contour blasting, which was conducted in the TASQ tunnel with high in-situ stresses in the Äspö Hard Rock Laboratory in Sweden.

Modeling horizontal insitu stress with flac3d