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Mining Publication: A Static Fatigue Constitutive Law for Joints in Weak Rock

NOTE: This page is archived for historical purposes and is no longer being maintained or updated. Contact NIOSH Mining if you need an accessible version.

Original creation date: April 1998

Image of publication A Static Fatigue Constitutive Law for Joints in Weak Rock

A constitutive model for rock interfaces based on the principles of static fatigue is proposed. The model is applicable to weak rock or joints with cohesion. Friction and dilation are decreased as plastic work increases. At equilibrium, the creep time increases by one time-step interval, and interface cohesion at each node decreased according to a power function. A constant-load, direct-shear simulation showed that the model is capable of mimicking constant-rate and tertiary creep and predicting failure. Tests on core from a coal mine showed constant-rate and, sometimes, tertiary creep, but also weak transitory creep. The cohesion deterioration function may need modification to simulate primary-phase creep. If model parameters are known for a site, the model can predict the onset of tertiary creep and failure. Such predictions can help engineers make better entry design and support decisions, which will reduce the likelihood of roof falls and increase safety for underground miners.

Authors: MK Larson

Conference Paper - April 1998

NIOSHTIC2 Number: 20000181

In Hans-Peter Rossmanith, ed. Proc Third Intl Conf on Mechanics of Jointed and Faulted Rock, Vienna, Austria; April 6-9, 1998, A.A. Balkema/Rotterdam/Brookfield; :171-177