Mechanical Behaviour of Reinforcement Elements Subjected to Shear

Strata control is one of the core risk areas in underground coal mining. The use of appropriate technology for ground support whether it be roof or ribs, primary or secondary and the effective management of this technology can be pivotal to achieving a safe and economical viable mining operation.

While much research has focused on the effects of axial loading of reinforcement elements in rock, less attention has been directed at understanding how these elements behave when subjected to shear loading. It is widely acknowledged that shear loads can have an important bearing on the stability of underground excavations; however, progress in this area has been hampered by the greater complexity of creating a physical model that can reliably simulate shear loading conditions. 

This project developed a facility that could be used to gain an understanding of the interaction between rock and reinforcement elements under shear loading conditions.  This helps to close the loop in terms of assessing the various conditions that are critical to the effective reinforcement of bedded/laminated roof conditions which is the domain of underground coal mines.

The findings in the report confirmed that there is only a limited understanding in terms of the effect of some parameters. There is less understanding as to the effect of the method of installation of reinforcement elements and the influence of different loading conditions such as loading rate, pretension, torque, axial tension and/or normal loading.

Results of the testwork have been peer reviewed in a paper entitled Development of a laboratory facility for testing shear performance of installed rock reinforcement tendons which was presented at the 2005 Conference on Ground Control in Mining, Morgantown, USA.