Abstract
Although the Lugeon test is widely used to measure the permeabilities of rock masses, this test has some problems to be solved. One of the largest problems is how to reduce the influence of the turbulent flow created near the bore hole. The turbulent flow may greatly reduce the measured permeability if the permeability of rock mass is large.
A possible technique to reduce the influence of the flow is to inject a highly viscous liquid instead of water. In this study, we tried to measure the permeability by using a highly viscous liquid at a damsite in the Oita prefecture. This area is mainly composed of fractured welded tuff. It was found that the high viscosity liquid was necessary for the measurement of the permeability in this area because the turbulent flow considerably decreased the measured permeability. A relation between the kinematic viscosity of the liquid used, injection pressure, and the Lugeon value obtained when using water was formulated. As a conclusion, the Lugeon test with a high viscosity liquid is a reliable method for the measurement of rock mass permeability.
The fracture geometries developed near bore holes were also examined by using a bore hole TV.
