Influence of stress dependent elastic moduli on plane strain solutions for boreholes : Duncan Fama, M E; Brown, E T Proc International Symposium on Rock at Great Depth, Pau, 28–31 August 1989V2, P819–826. Publ Rotterdam: A A Balkema, 1989

Abstract

The elastic moduli of porous or clastic rocks are not always constant but may increase with increasing minor principal stress. Previous studies of circular excavations in hydrostatic stress fields have shown that, for this class of rock, classical constant modulus linear elastic theory can lead to erroneous predictions of the initiation and extent of failure around excavations. A plane strain finite element Program has been adapted to extend these solutions to the case in which the in situ stresses in the plane of the excavation cross-section are not hydrostatic. Previous conclusions are confirmed for non-axisymmetric loading. The influences of the ratio of the major and minor principal stresses in the plane of the cross-section and of the internal borehole pressure are evaluated. The boundary conditions used are shown to influence the numerical results obtained for cases involving stress dependent elastic Moduli.