Weakening Technology of Hard Coal Seam Based on Improving Coal Cutting Efficiency

To solve the problem of the coal cutting difficulty of shearer and the inefficient coal cutting efficiency in fully mechanized mining face with hard coal seam which was affected the normal production, theoretical analysis, numerical simulation and field measurement were combined to study the support and surrounding rock relationship. The method for determining the reasonable working resistance of hydraulic support in fully mechanized mining face of hard coal seam based on improving coal cutting efficiency and roof control was proposed. The research showed that it is beneficial to increase the width of coal plastic zone of coal wall and raise the degree of pre-cracking of hard coal seam by reducing support working resistance under the constant load of overlying rock. The reasonable working resistance of support range was between 7 200 kN to 8 400 kN under the condition of ensuring coal cutting efficiency and top plate effective support. The coal cutting time is positively correlated with working resistance of the support through on-site measurement. It was beneficial to improving the coal cutting efficiency of the shearer adjusting support working resistance properly.