The permeability in fractured rock mass is expected larger in the excavation-damaged zone than in the non-damaged zone. Hence, it is possible to find out the damaged zone based on the permeability measured by the pressure recovery test in the borehole. In this case, it is important to konw how the randomness of openings affects the results of pressure recovery test.
Numerical 2D-model of fractured rocks were used herein to study the variation in the pressure recovery process due to the randomness of openings. The results show that if the loosened zone extends beyond the test section the pressure recovery becomes definitely fast.