| The influence of tunnel shape on rockburst manifestation is analyzed in FLAC3D using several indicators includingvelocity and acceleration within the finite difference method. The tunnel is constructed in a rockmass defined by a Mohr-Coulombstrain-hardening/-softening constitutive law to approximate rockburst-prone brittle rock. Three cross-sectional tunnel shapes areemployed: circular, horse-shoe, and rectangular. The analysis is performed as a two-dimensional problem with an applied planestrain condition and a stress boundary used to simulate earth pressure. No supports are installed in the analysis for simplicity sincethe rockmass failure mode is the focus of this study. The influence of tunnel shape on rockburst manifestation is analyzed usingseveral indicators of unstable failure. The results indicated that the circular tunnel geometry is more stable than the other tunnelshapes against the occurrence of rockburst. The rectangular tunnel produced the highest magnitudes of the rockburst indicators andproved to be the most unstable of the three geometries which were tested. |
