Determination of the stress state in a rock mass subjected to excavation

This paper develops a model that allows the variation in the stress state in an area of ground to be determined, especially in the rock mass, as a consequence of human activity. It does so through the basis of measurements carried out at three boreholes that are neither co-linear nor co-planar and which are oriented towards the area in which the stress state is to be determined. More specifically, the method uses the data obtained from the measurement of the variations in diameter in each of the boreholes as a result of the alteration of the stress state of the rock mass, and calculates the deformation in three directions, perpendicular to one another. An elastic behaviour is assumed to obtain the state of stress. Finally, the paper reports a practical application of the method in an underground coal mine in Asturias (Spain), where it was possible to measure the stress states of the rock walls of the mined seam.