ABSTRACT
The biaxial “doorstopper” cell for rock stress measurements has for some 25 years been used for absolute rock stress determinations in Norway. The method has proved to be fast and relatively inexpensive with reasonable reliability, at least in cases where the stressfield may be assumed to be nearly uniaxial or biaxial with zero or close to zero stress parallel to the measuring borehole. The traditional doorstopper is, however, not very suitable for long time, rock stress change monitoring. Continuous monitoring can easily be established by a permanent connection to a strain gauge bridge/scanner and plotter/printer. A major concern in connection with longtime measurements is the stability of the measuring system as such. The unloaded control doorstopper kept on the measuring site during the whole periode has showed very small changes, indicating that the measuring system as such is stable enough for practical purposes.
