Analysis of the Influence of Upper Protective Layer Mining on the Effect of Pressure Relief and Protection of Coal and Rock Masses between the Lower Overburden Layers

<table class="table-group" id="tab4"><tr><td><table class="table"><tr><td class="thead-hr" colspan="6"><hr/></td></tr><tr class="thead"><td class="align_left">Category</td><td class="align_center">Density (kg/m<sup>3</sup>)</td><td class="align_center">Bulk modulus (GPa)</td><td class="align_center">Shear modulus (GPa)</td><td class="align_center">Internal friction angle (°)</td><td class="align_center">Dilatancy angle (°)</td></tr><tr><td class="thead-hr" colspan="6"><hr/></td></tr><tr><td class="align_left">Value</td><td class="align_center">2000</td><td class="align_center">11.1</td><td class="align_center">8.3</td><td class="align_center">13</td><td class="align_center">7</td></tr><tr class="table-tr"><td colspan="6"><hr class="tbody-hr"/></td></tr></table></td></tr></table>

<div>Mechanical parameters of main rock materials in the goaf.</div>

Advances in Civil Engineering

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Table 4

Table 4: Analysis of the Influence of Upper Protective Layer Mining on the Effect of Pressure Relief and Protection of Coal and Rock Masses between the Lower Overburden Layers 

Table 4 | Analysis of the Influence of Upper Protective Layer Mining on the Effect of Pressure Relief and Protection of Coal and Rock Masses between the Lower Overburden Layers 