Numerical treatment of progressive localization in relation to borehole stability

Abstract

Abstract Results of large‐scale finite element computations are presented for the problem of borehole failure due to the high stresses at great depths. Rock is modelled by an extension of the Mohr–Coulomb flow theory of plasticity for material with Cosserat micro‐structure. The introduction of internal length (grain size) improves the computational stability and allows for robust post‐localization computations. The presented results show clearly a progressive failure mechanism and the computed failure modes are in a good qualitative agreement with laboratory and field observations.