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

Fault Family
Table 4.3: Strength parameters assigned to shear families for Case 2.
Cohesion
(MPa)
Friction
Angle (º)
Geological Description
E–W-striking shears 5 35 No seismicity or damage
and splays
Footwall Shear 0 35 No Seismicity but visible
damage
SW-striking shears 0 20 Associated seismicity,
damage and/or reinforcement
necessary
The southwest-striking fault system is interpreted to be the weakest (Table 4.3). As found in Case
1, this fault system has the most influence on the stress field; the east-west striking shear zones
and the Footwall Shear Zone show little influence.
There is little difference between the modelled results for Case 2 and Case 1. Model results can
be found in Appendix D. The moderately strong fault condition produces a realistic stress
distribution. In both plastic and elastic models, low stresses occur adjacent to the excavation and
high stresses (Fig. 4.10) and high differential stresses (Fig. 4.11) align with SW-striking shear
zones to the south of the excavation. Right-lateral displacement is induced along the Plum and
the Return Air Raise Shear Zones in this area (Fig. 4.12). In the plastic model, damage shows
some alignment with the SW-striking shear zones to the south of the excavation (Fig. 4.13).
Figure 4.10: Model of maximum stress for Case 2 for (A) elastic model and (B) plastic model. Faults are
assigned a cohesion of 0 MPa and a friction angle of 35 degrees. Scale is in MPa.
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