A Three Hinge Buckling Laboratory Test

Abstract

Near-surface buckling of horizontally laminated sedimentary rock has been reported to occur in Ontario, Canada and the Upper Midwestern U.S. where high horizontal in situ stresses occur. Often referred to as ‘pop ups’, these buckling events typically occur suddenly and are commonly accompanied by a rapid energy release akin to rock bursting. In recent years, this mode of instability has become a concern for surface mining and quarry operations, in particular in cases where the buckling failure creates a connection between an underlying aquifer and the excavation. Despite previous research on the topic of buckling instability, there remains many limitations in development of a design methodology to account for buckling failure. The main objective of this research study is to experimentally investigate a simple buckling failure mode, known as three hinge buckling (THB): buckling that involves rotation of a two-rock block configuration with a central hinge. An experimental testing procedure was developed to reproduce THB at laboratory scale, including the design and fabrication of a new testing apparatus and development of a testing methodology. A preliminary THB test was conducted and the results are presented. A simplified, elastic block numerical model was developed using the distinct element method code 3DEC in order to provide insight into the laboratory experiment. Overall, this newly-developed test was able to reproduce the THB failure experimentally in the laboratory and to provide an opportunity to observe the brittle buckling failure to obtain valuable, quantifiable information about the failure process.