Rock masses consist of intact rock and discontinuities, where discontinuities plays major role in rock masses permeability and are defined as main flow paths. Rock masses permeability are closely affected by stresses on it and permeability changes depending on applied stresses. In this paper the effect of stress changes on rock mass permeability are studied at two state of loading. Stresses are applied with constant rate and incremental rate on rock masses and relevant permeability were obtained. Rock mass is considered as a three-dimensional discrete fracture network with random distribution of joints orientation model. Results shows that at the constant rate loading rock mass behavior is under the control of joints closure and the permeability is decreases. However with varying rate loading, the fracture dilation is recorded and permeability increased.
Key words: stress-flow, discrete fracture network, rock mass, permeability.