Determination of Far Field Stress from the Point Stress Measurement, a Numerical Approach

The combination between numerical methods and field measurements have been used by many researchers to analyze rock engineering problems. In numerical analyses, the far field stress state should be postulated at the beginning. As the results, however, it happens that generally the calculated stress does not match correctly with the measured stress. The fault can be addressed to the postulated far field stress state, since the high confidence of in-situ measurement technique has been used. In order to eliminate this difference, a kind of back analysis has been developed by the authors to determine the far field stress state using 3D FSM (3 Dimensional Fictitious Stress Method). The model of topography and the real field case were used to confirm the applicability of the calculation procedure. From this study, it is shown that the method is convenient to determine correctly the far field stress state, if the topography perturbation of the stress state at an arbitrary point A can be modelized using FSM, and if each component of the far field stress state is defined as a linear function of depth.