Method of detecting permeable zones in advancing underground works

摘要

An advancing drill hole 11 is made in the working face 11a of the gallery 10. Next: a. The water pressure in the drill hole is brought to a value different to the equilibrium pressure; b. The entrance of the drill hole is closed and the pressure is allowed to return to equilibrium pressure, whilst recording the values of pressure versus time; c. The curve of pressure versus time is plotted and compared with a theoretical model. Anomalies indicate the presence of a permeable zone 12 located in the vicinity of the drill hole, but not intersecting with it. IMAGE