Study on Stress Relief of Hard Roof Based on Presplitting and Deep Hole Blasting

<table class="table-group" id="tab2"><tr><td><table class="table"><tr><td class="thead-hr" colspan="5"><hr/></td></tr><tr class="thead"><td class="align_left">Peak load (MPa)</td><td class="align_center">Loading time <i>t</i><sub>R</sub> (s)</td><td class="align_center">Unloading time <i>t</i><sub>S</sub> (s)</td><td class="align_center">Minimum critical damping ratio</td><td class="align_center">Minimum center frequency (Hz)</td></tr><tr><td class="thead-hr" colspan="5"><hr/></td></tr><tr><td class="align_left">20</td><td class="align_center">0.01</td><td class="align_center">0.05</td><td class="align_center">0.05</td><td class="align_center">5.12</td></tr><tr class="table-tr"><td colspan="5"><hr class="tbody-hr"/></td></tr></table></td></tr></table>

Advances in Civil Engineering

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Table 2

Table 2: Study on Stress Relief of Hard Roof Based on Presplitting and Deep Hole Blasting 