An overview of rock stress measurement methods

This paper presents an overview of methods that have been used to estimate the state of stress in rock masses, with the emphasis on methods applicable to hard rocks and Scandinavia. Rock stress is a difficult quantity to estimate because the rock stress measuring techniques consist of perturbing the rock, measuring displacements or hydraulic parameters, and converting the measured quantities into rock stresses. There are two main types of method: those that disturb the in situ rock conditions, i.e. by inducing strains, deformations or crack opening pressures; and those that are based on observation of rock behaviour without any major influence from the measuring method. The most common methods are briefly described including their application areas and limiting factors.