Experiments with rock: observations of fracture
Event details
| Date | 24.05.2013 |
| Hour | 14:00 › 15:30 |
| Speaker | Prof. Labuz (head of the CE dept. of the university of Minneapolis) |
| Location |
GC B1 10.
|
| Category | Conferences - Seminars |
It is evident from a strength test conducted on a specimen of rock that failure is associated with initiation and propagation of fracture. The rock may deform uniformly until a critical condition is reached, and then deformation localizes in a zone that opens and/or slides. Because of the presence of the fracture, a structural size effect on the overall response appears, and energy released from the failure process can be sudden or gradual. Controlling failure is often necessary to achieve safe operations of underground mines, while promoting failure efficiently is a concern in excavating and drilling. Thus, the conditions to initiate and propagate a fracture are often needed for proper designs in rock.
Details of tensile fracture from flexural tests are reported based on the optical methods of speckle interferometry and image correlation, which provide high-resolution measurements of crack displacements. Acoustic emission, which are elastic waves emitted during the fracture process, deliver information on location and mechanism of microcracking. Fracture characteristics such as critical crack opening and process-zone length are highlighted.
An interpretation of shear fracture is discussed in relation to plane strain compression tests, where growth of a failure plane is observed at various stress states. Displacement measurements, AE locations, and thin-section microscopy allowed direct and indirect observations of in-plane propagation, and fracture mechanics was used to determine the shear fracture toughness of the rock.
Will be followed by a lecture of A. Ferrari "An experimental and constitutive investigation on the chemo-mechanical behaviour of a clay"
Details of tensile fracture from flexural tests are reported based on the optical methods of speckle interferometry and image correlation, which provide high-resolution measurements of crack displacements. Acoustic emission, which are elastic waves emitted during the fracture process, deliver information on location and mechanism of microcracking. Fracture characteristics such as critical crack opening and process-zone length are highlighted.
An interpretation of shear fracture is discussed in relation to plane strain compression tests, where growth of a failure plane is observed at various stress states. Displacement measurements, AE locations, and thin-section microscopy allowed direct and indirect observations of in-plane propagation, and fracture mechanics was used to determine the shear fracture toughness of the rock.
Will be followed by a lecture of A. Ferrari "An experimental and constitutive investigation on the chemo-mechanical behaviour of a clay"
Practical information
- General public
- Free
Organizer
- EPFL-ENAC-LMS
Contact
- A. Ferrari