Experimental investigations into sacrificial support for containment of rockburst damage

Abstract

Recently, a support method termed 'sacrificial support' was proposed as a potential additional method to prevent rockburst damage, based on observations made after rockburst events in a mine. The philosophy behind a sacrificial support system is that: under dynamic loading conditions support, in the form of a liner, must fail leaving behind, undamaged, what was once supported rock mass. In this paper, spalling tests based on Split Hopkinson pressure bar technique were conducted to study some aspects of dynamic rock fracturing in tension at high strain rates and the role a sacrificial layer plays in combating dynamic rock failure. To achieve this, a single Hopkinson pressure bar, with a long cylindrical intact rock specimen attached at the bar free end, was impacted by a striker on the opposite free end of the bar in order to generate a dynamic stress pulse responsible for spall failure upon reflection from the specimen free end. Different liners and/or liner combinations were then introduced at the specimen free end as support. Such a simple, yet robust experimental setup , allowed the potential benefits and failure mechanisms associated with sacrificial support under dynamic loading to be demonstrated. Analysis of experimental results revealed that varying liner thickness and mechanical impedance between rock and support liner plays a significant role to help limit rockburst damage.