Recent rock fracture mechanics developments  Fulltext 

[ Ove Stephansson ] - Department of Land and Water Resources Engineering Royal Institute of Technology, Stockholm, Sweden and CeoFonchungsZenhum, otsdam, Gemany

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Rock fracture mechanics dates hack to mid 1960 and its application to rock hurst prohlems and collapses in deep gold mines of South Africa. The theory of fracture mechanics provides a means of determining the fracture stress of a stnrcttrre in material containingflaws or microcracb of known size and orientation in terms of a stress intensity factor K Tension mode (Mode I) or mired tension and shear mode (Uode I and II) fracturing are most important in rock mechanics and rack engineering. A new rack fracture toughness testing in Mode II called Punch- firinrgh Shear Te~LtY introduced and e-rperimental resultsf or three dryerent rock tjpes tested at dgfferent confining presstrre are presented. Frachrre toughness data are used for simulation of mired mode fracture propagation of rocks with a new strain energy release rate criterion, called F-criterion. The criterion has heen implemented in a new fracture mechanics program called FRACOD? The basic features of the code are
given and resultf rom simrrlation~o f horehole breakouts and fracture propagations around a canister horehole for disposal of .spent nuclear frrel are presented.