Tests on mechanical properties of model fracture zones

Fracture zones are commonly found in the Earth’s crust. Therefore, it is almost impossible not to encounter these zones during large rock excavations. These zones are always problematic causing heavy water in-flow, instability, squeezing etc. during excavation. Therefore, the assessment of mechanical characteristics of these zones is quite important. Nevertheless very few studies undertaken so far on this aspect of fracture zones. In this paper, the results of tests on the mechanical properties of model fracture zones are presented. Tests involve uniaxial compression tests, direct shear tests and elastic wave velocity measurements. Furthermore, several techniques for assessing mechanical characteristics of fracture zones is briefly outlines and the assessed mechanical properties by these techniques are compared with experimental results on model fracture zones.