Rock mass hydraulic conductivity of the Bukit Timah granite, Singapore

Field tests were conducted to determine the rock mass hydraulic conductivity through double packer constant pressure, rising and falling head tests in boreholes. The field results indicated that the Bukit Timah granite is massive and has the hydraulic conductivity of 10−10–10−8 m/s, with isolated discontinuity zones having the hydraulic conductivity of 10−7–10−6 m/s. The rock mass hydraulic conductivity generally decreases with increasing depth. The field data provide a base for assessment and prediction of water inflow to rock tunnels.