Application of numerical methods in the interpretation of stress measurement results in rock masses

Abstract

This paper presents a methodology that has been used by LNEC to estimate the initial stress field in rock masses, from the results of in situ stress measurements, using numerical methods. This methodology considers the rock mass conditions, such as the ground topography, the pre-existence of underground openings and the rock mass heterogeneity. The types of tests that were performed are presented, as well as examples of application of the methodology in studies carried out for estimating the stress field to be used in the design calculations of several underground works constructed in Portugal. A recent case study of the determination of the initial stress field for the design of an underground powerhouse, excavated in a heterogeneous rock mass, is presented in detail. A number of aspects of the construction of the complex three-dimensional model are summarized and the results are discussed.