NORMAL WEDGE INDENTATION IN ROCKS WITH LATERAL CONFINEMENT

The paper reports results of a numerical analysis of the wedge indenta tion problem. The main objective of this research is to investigate th e influence of the lateral confining stress ao on the development of t he plastic zone under the indenter and on the initiation of tensile fr actures. Numerical analysis indicates that the location of maximum ten sile stress (interpreted as the point of crack initiation) moves away from the indentation axis as the lateral confinement increases. It is found that a small increase in the confining stress from zero induces a large increase in the inclination of this point on the indentation a xis. However, the confinement does not reduce significantly the maximu m tensile stress and it hardly influences the indentation pressure. Th ese numerical results shed some light on the mechanism of formation of lateral or sub-horizontal tensile cracks observed in the indentation experiments.