Time-dependent behaviour of deep level tabular excavations in hard rock

Authors
Citation
Df. Malan, Time-dependent behaviour of deep level tabular excavations in hard rock, ROCK MECH R, 32(2), 1999, pp. 123-155
Citations number
48
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Geological Petroleum & Minig Engineering
Journal title
ROCK MECHANICS AND ROCK ENGINEERING
ISSN journal
0723-2632 → ACNP
Volume
32
Issue
2
Year of publication
1999
Pages
123 - 155
Database
ISI
SICI code
0723-2632(199904/06)32:2<123:TBODLT>2.0.ZU;2-U
Abstract
Although hard rock is not usually associated with large creep deformation, significant time-dependent behaviour is observed in the tabular excavations of the South African gold mines. Time-dependent closure data was collected in stopes of the Ventersdorp Contact Reef and Vaal Reef. This data typical ly consists of a primary closure phase after blasting, followed by a steady -state closure phase. This closure behaviour is the result of the rheology of the fracture zone around these excavations and the time-dependent extens ion of this zone following a mining increment. An elasto-viscoplastic appro ach was developed to simulate the time-dependent nature of the fracture zon e. This model proved successful in simulating the experimental closure prof iles. It appears that the closure data may provide useful diagnostic inform ation of the stress conditions in the fracture zone ahead of the face. This may possibly be used to identify hazardous conditions such as areas prone to face bursting. The effect of preconditioning on the time-dependent closu re behaviour is also illustrated.