This paper presents the experimental results obtained with a two-dimensional indentation device controlled by a servo-hydraulic loading system and monitored with the nondestructive techniques of acoustic emission and electronic speckle pattern interferometry. The goals of this research were to evaluate the indentation pressure as well as the size of a damage (plastic) zone, and to study the initiation of tensile fracture at the intact rock-damaged rock boundary, that is, the elasto-plastic interface. The key factors controlling the failure process are (1) the mechanical properties of the rock including the elasticity and strength parameters, (2) the geometric features of the tool such as the wedge angle, and (3) the lateral confinement simulating the far-field stress. A good agreement with regard to indentation pressure and damage-zone radius was found between the experimental and theoretical analyses. Furthermore, the intrinsic crack length, critical in establishing tensile fracture, was estimated and correlated to the grain size.
|Original language||English (US)|
|Number of pages||11|
|Journal||International Journal of Rock Mechanics and Mining Sciences|
|State||Published - Oct 2006|
Bibliographical noteFunding Information:
Partial support was provided by National Science Foundation Grants CMS-9612035 & CMS-0070062 and the Minnesota Supercomputer Institute. E. Detournay and H. Huang contributed substantially to the projects. L. Biolzi and S. Cattaneo (Politecnico di Milano) assisted with ESPI.
- Acoustic emission
- Cavity expansion model
- Crack propagation
- Speckle interferometry
- Wedge indentation