title of the thesis - Department of Geology - Queen's University

zones are planar in geometry, are of uniform strength and are laterally continuous beyond the
limits of the mine, though in reality shears may be discontinuous and have variable orientations
and properties.
Table 4.1: Rock mass and discontinuity model properties
Rock mass Properties
Discontinuity Properties
Property Value Property Value Range
Cohesion (C) 10 MPa Cohesion (C) 0-10 MPa
Friction Angle (Φ) 35° Friction Angle (Φ) 10-35°
Density † (ρ) 2965 kg/m 3 Normal Stiffness †† 700,000 MPa/m
Young’s Modulus (E) 35 GPa Shear Stiffness †† 99,400 MPa/m
Poisson Ratio (υ) 0.263 Tensile Strength 0-10 MPa
Bulk Modulus * (K) 24,613 MPa
Shear Modulus * (G) 13,856 MPa σ 1 (E-W) ††† –102.7 MPa
σ 3 (N-S) †††
–73.4 MPa
*
Calculated
†
Density from Tulk (2001)
††
Stiffness values increased to prevent contact overlap in UDEC
†††
Maximum and minimum stresses (in plane) calculated from overcoring measurements
Two different approaches are used to load the model once the geometry, properties of the material
and discontinuities are specified
1. A homogeneous stress field was initiated within the model and at the boundaries
2. Incremental displacements were used to synthesize tectonic loading
Methods and results for both loading methods are discussed in the following sections. Boundary
conditions for both models are depicted in Figure 4.5.
Staged models were also created to better understand the effect of mining on the stress field and
induced fault slip. This allowed the rock mass and faults to come to equilibrium without an
excavation. UDEC code for the models used in this research can be found in Appendix E.
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