Pressure relief mechanism and support technology of immediate roof cutting gob-side entry retaining
The No.9 coal seam of Yunjialing Mine is under thick and hard rock strata,and the mine pressure in the stope is strong,and it is hard to control the surrounding rock using the traditional gob-side entry retaining method.Taking the engineering background of the transportation roadway of 19103 working face in Yunjialing Mine,the mechanical equilibrium conditions of thick and hard immediate roof of gob-side entry retaining with roof cutting are analyzed,and it is concluded that the support resistance of no less than 1046 kN should be provided beside the roadway.The numerical simulation method was used to compare the deformation and stress of surrounding rock and the distribution of plastic zone of gob-side entry retaining with and without roof cutting under thick and hard immediate roof.The results show that the roof of goaf is more likely to collapse after roof cutting.The subsidence of the roof of the retaining roadway is only 28.2%of that without roof cutting in the same period.After roof cutting,the vertical stress of the roof on the side of the retaining roadway becomes smaller,the horizontal stress increases and the plastic zone of the surrounding rock transfers to the deep part of the roof and floor.It is revealed that the mechanism of pre-splitting roof cutting pressure relief is to block the transmission of dynamic pressure in the working face and induce the roof of the goaf to fall in advance to meet the roof pressure.The increase of horizontal stress is caused by the deformation of the long and short cantilever beam formed on both sides of the slit.The roof control idea for gob-side entry retaining with thick and hard immediate roof is proposed as centralized support of the cutting end,appropriate pressure relief and formation of combined cantilever beam.The comprehensive support technology of long and short anchor cable,single hydraulic prop and yielding U steel beam is adopted,and the sealing measures of hanging mesh shotcreting are adopted.The field industrial test results are good,the peak stress of the anchor cable of the roadway roof after cutting the roof is about 350 kN,after the surrounding rock is stable,the specifications meet the conditions of secondary reuse.
gob-side entry retainingpre-splitting and roof-cuttingthick and hard immediate roofmechanism of pressure relieflong cantilever beam
NETL
NSTL
万方数据
