TY - GEN
T1 - Influence of confinement dependent failure processes on rock mass strength at depth
AU - Valley, Benoît
AU - Kim, Bo Hyun
AU - Suorineni, Fidelis T.
AU - Bahrani, Navid
AU - Bewick, Rob P.
AU - Kaiser, Peter K.
PY - 2012/2/13
Y1 - 2012/2/13
N2 - Changes of failure mechanism with increasing confinement, from tensile to shear dominated failure, is widely observed in the rupture of samples in laboratory and in rock masses in situ. However, common failure criteria typically consider only shear mechanisms. A hybrid criteria based on a sigmoid function is introduced to account for a transition from tensile to shear dominated failure with increasing confinement. When evaluated by fitting to an extensive laboratory database the sigmoid criteria does not provide a better fit compared to the Hoek-Brown failure envelope, but provides insight into rock strength controlling factors that have significant consequences with respect to the interpretation of laboratory test results. It also leads to a differentiated approach for design by considering two types of behaviour process: 1) in the inner shell, i.e. the direct vicinity of openings, the failure mode is dominated by tensile cracking leading to spalling and related geometric dilation processes and 2) in the outer shell, i.e. remote from excavations, where confinement promotes interlock, we suggest that rock masses could be significantly stronger than predicted by standard approaches.
AB - Changes of failure mechanism with increasing confinement, from tensile to shear dominated failure, is widely observed in the rupture of samples in laboratory and in rock masses in situ. However, common failure criteria typically consider only shear mechanisms. A hybrid criteria based on a sigmoid function is introduced to account for a transition from tensile to shear dominated failure with increasing confinement. When evaluated by fitting to an extensive laboratory database the sigmoid criteria does not provide a better fit compared to the Hoek-Brown failure envelope, but provides insight into rock strength controlling factors that have significant consequences with respect to the interpretation of laboratory test results. It also leads to a differentiated approach for design by considering two types of behaviour process: 1) in the inner shell, i.e. the direct vicinity of openings, the failure mode is dominated by tensile cracking leading to spalling and related geometric dilation processes and 2) in the outer shell, i.e. remote from excavations, where confinement promotes interlock, we suggest that rock masses could be significantly stronger than predicted by standard approaches.
KW - Rock properties
KW - Site characterization
UR - http://www.scopus.com/inward/record.url?scp=84863057040&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84863057040&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84863057040
SN - 9780415804448
T3 - Harmonising Rock Engineering and the Environment - Proceedings of the 12th ISRM International Congress on Rock Mechanics
SP - 855
EP - 860
BT - Harmonising Rock Engineering and the Environment - Proceedings of the 12th ISRM International Congress on Rock Mechanics
T2 - 12th International Congress on Rock Mechanics of the International Society for Rock Mechanics, ISRM 2011
Y2 - 18 October 2011 through 21 October 2011
ER -