Methods of in situ Stress Measurement

Compared with other rock mass properties, rock stress is a difficult quantity to measure. As pointed out by Leeman (1959), ‘It is impossible to measure stress directly since, in fact, it is a fictitious quantity. It is only possible to deduce the stresses in a solid body from the results of measurements using some indirect method’. Since stress can be represented by a secondorder Cartesian tensor, determination of the complete in situ stress field in three dimensions requires at least six independent pieces of information.