Stress and time-dependent fracture around cavities in physical models of potash salt rock

Fractures are common in the potash mines of Saskatchewan and represent possible conduits for water inflow. Physical model experiments, using blocks of potash with cavities, were used to monitor the initiation and propagation of fractures under a uniaxial compressive load. Discrete fractures are stable but they lead to additional, off-set cracks and thus, the total crack length increases exponentially with increasing stress. For a constant load, there is a threshold stress level, at about 50% of the uniaxial compressive strength, above which the rate of total crack length growth increases with time, similar to a tertiary creep curve.

• INTRODUCTION

• MODELING PROGRAM

• FRACTURE EVOLUTION AROUND THE CAVITIES

• FRACTURE GROWTH IN COMPRESSION

• CONCLUSIONS

• ACKNOWLEDGEMENTS

• REFERENCES