Numerical modeling simulations of spray-on liners support potential in highly stressed and rockburst prone rock conditions

Rock Engineering 2009 - Rock Engineering in Difficult Conditions
Abstract Future underground mining activity will take place at greater depth, and will be accompanied by an increased incidence of stress and rockburst-induced rock falls. This has generated interest by the mining industry, and others, towards developing innovative and effective support systems capable of mitigating dynamically-induced rock falls. One principal area of research focuses upon application of rapidly-deployable spray-on membrane support media, commonly designated as thin spray-on linings (TSLs).

Extensive research has been undertaken to characterize the support capabilities of TSLs, and to assess their capacity for inhibiting damage created by mining-induced rockbursts. A variety of TSLs and other spray support media were subjected to the effects of simulated rockbursting, through use of explosive detonation trials, to evaluate their damage mitigation value. The relative effectiveness of area support materials for suppressing dynamic rock fragmentation and support media damage was assessed using near- and far-field seismic monitoring and high-speed digital photographic analysis of repetitive blasting trials. The results of these trials have demonstrated that the majority of thin, spray-on lining products currently available are highly effective for mitigating rockburst damage in highly stressed mine environments. It is, however, considered that such test procedures are not only time consuming and expensive but requires verification procedures. Numerical modeling procedures were developed to better understand the behaviour of TSL’s, a factor that is essential when designing any rock support system. A series of numerical modeling assessments were conducted using FLAC3D modeling of a half circular TSL-lined tunnel, influenced by anisotropic stresses, to investigate the support potential of TSLs under prototype conditions. The effect of mine rockburst was also simulated using the three-dimensional dynamic analysis option of FLAC3D.

Results of TSL-lined tunnels in a highly stressed and mine rockburst conditions indicated exceptional effectiveness of TSLs for suppressing rock deterioration resulting from stresses and rockbursts. The rock support potential of TSLs on tunnel surfaces was compared with that of thin shotcrete linings, and results indicated that thin spray-on lining products currently available may be equally as effective in support as shotcrete materials.
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