Design and Application of Blasting Parameters for Presplitting Hard Roof with the Aid of Empty-Hole Effect

<table class="table-group" id="tab3"><tr><td><table class="table"><tr><td class="thead-hr" colspan="4"><hr/></td></tr><tr class="thead"><td class="align_left"><i>mxpres</i> (MPa)</td><td class="align_center"><i>mnpres</i> (MPa)</td><td class="align_center"><i>mxeps</i></td><td class="align_center"><i>mneps</i></td></tr><tr><td class="thead-hr" colspan="4"><hr/></td></tr><tr><td class="align_left">58.2</td><td class="align_center">−2.6</td><td class="align_center">2<i>e</i> − 3</td><td class="align_center">−8<i>e</i> − 4</td></tr><tr class="table-tr"><td colspan="4"><hr class="tbody-hr"/></td></tr></table></td></tr><tr class="table-fn"><td><div><i>Note</i>. <i>mxpres</i>: the maximum hydrostatic pressure should be taken as a positive value, representing pressure. The option is used for controlling the compression failure. <i>mnpres</i>: contrary to <i>mxpres</i>, it is used for controlling tensile failure, generally taking negative value. <i>mxeps</i>: the extreme value of principal strain is used for controlling compression failure, generally taking positive value. <i>mneps</i>: contrary to <i>mxeps</i>, it should be taken as a negative value. This option is used for controlling tensile failure.<br/></div></td></tr></table>

Shock and Vibration

tab3

Table 3

Table 3: Design and Application of Blasting Parameters for Presplitting Hard Roof with the Aid of Empty-Hole Effect 