Integration of three-dimensional continuum model and two-dimensional bonded block model for studying the damage process in a granite pillar at the Creighton Mine, Sudbury, Canada

Abstract

Bonded block model (BBM) has shown potential in replicating rock mass behavior as well as the rock–support interaction mechanism, but their practical application is limited to two dimensions due to the high associated computational demand. To allow for the use of BBM in simulating three-dimensional (3D) problems, this study proposes an integrated 3D continuum–two-dimensional (2D) discontinuum approach, in context of rock pillars. A cross-section of a granite pillar was simulated using a BBM with a load path from a calibrated mine-scale FLAC3D model. Pillar support as employed in the mine was also incorporated in different stages during the simulation. The model was calibrated by varying the input parameters until the displacements at six locations within the pillar matched those measured by a multi-point borehole extensometer (MPBX) in the field. The calibrated model was subsequently used to understand how the support and load path influenced the damage evolution in the pillar. The shear component of the load path was found to have a major effect on the severity and extent of the damaged regions. When the support density was increased in the model, the lateral displacements along the pillar walls were significantly suppressed in a somewhat unpredictable manner. This was explained by the interaction between the supports and the damaged regions at the corners, which ultimately modified the stresses along the pillar periphery. The amount of displacement reduction obtained by increasing the support density illustrates the potential of BBM to be used as a support design tool.