Demonstration of over core stress measurement from surface using the Sigra IST tool

Abstract

This report contains a description of the stress measurement process and the results of the stress measurements at Goedehoop. The results of the stress measurements show a very low horizontal stress regime but one in which the stresses are consistent in magnitude and direction. The major principal effective stress is in the region of 4 to 5 Mpa, which is small in the context of a rock UCS of 100 MPa. Of more concern if long wall mining were being considered is the minor principal stress which is in the range of 0.4 to 2 MPa. This low stress could lead to caving problems. In the context of the bord and pillar mining being used the stress regime is considered benign