Prediction of rock parameters from micro-indentation measurements: the effect of sample size

摘要

Mocro-indentation measurements have been performed in order to investigate the possibility of extracting rock mechanical properties from snall rock samples. The tests were performed with a 1 mm flat indenter. Two parameters were determined when analyzing the indentation measurements: The Indentation Modulus (IM) and the Critical Transition Force (CTF). IM is the slope of the force-displacement curve, corrected for deformations in the load frame. CTF is defined as the force level shwere the material deforms without significant change in the applied force. The rock samples were casted in a mounting material (Demotec 30), in order to stabilize the sample during testing, and simplify surface preparation. The upper and lowe surfaces of the samples were made flat and plane parallel by grinding. 15 materials were tested, including sandstones, limestones and shale/clay materials with different strengths and stiffness.