Estimation of three-dimensional stress distribution and elastic moduli in rock mass of the Tono area

Abstract

In mining and civil engineering, it is essential to understand an in situ stress state when dealing with underground excavations. An in situ stress state can be complicated due to rock mass heterogeneities, geological structures, topography, tectonic movements, etc. Several in situ stress measurement techniques have been developed to provide more reliable data for the design of underground openings. The results obtained from field measurement, however, often only represent a local stress state in a rock mass where the measurement was taken. This study presents a back analysis based on three-dimensional finite element analysis in order to estimate regional stress fields and the elastic moduli of a rock mass simultaneously from in situ measurements. In order to improve the accuracy of the estimation of a three-dimensional stress field, heterogeneities in a rock mass consisting of geological layers with different elastic properties were considered. Back analysis was applied to determine the regional stresses for a broad field study that includes the Tono Mine, the Shobasama Site and the Mizunami Underground Research Laboratory (MIU) Construction Site.