Improvement in the interpretation of stress measurements by use of the overcoring method : development of a new approach
Amélioration de l'interprétation des mesures de contrainte par surcarottage : développement d'une nouvelle méthode d'interprétation
Abstract
The overcoring method is one of the methods the most frequently used in geotechnics for stress measurements. It has been shown to be highly suitable for measuring the stresses in hard and sound rocks. But applied to some rock formations and under some local conditions, many overcoring stress measurement compaigns have ended to failure. Interpretation of the measurements by the conventional method produces erroneous results. These failures are due mainly to the worst assumption that the behaviour of the rock is elastic and that a sound core is obtained. So it is impossible to use the interpretative conventional method. To overcome these problems and in order to determine the stress tensor from deformations recorded under such conditions we have been developed a new method which is based on an analysis of the start of the deformation curves ; this method is the subject of this paper