Research on Pre-Splitting Roof Control Technology of Thick and Hard Roof Without Coal Pillar Under Secondary Mining
Pre-splitting roof control is one of the main technical means to improve the strong mine pressure behavior of thick and hard roof on the adjacent surface of gob-side entry retaining.Aiming at the problem of difficult caving of thick and hard roof in secondary mining of 1615A working face in Zhangji Mine,theoretical analysis,numerical simulation and field practice were used to study.Through theoretical analysis,the roof mechanical model of pre-splitting roof cutting in working face was established,and the expressions of roof displacement and weighting step distance under four working conditions were obtained.The first weighting step distance without pre-splitting roof cutting is 50.06 m,and the periodic weighting step distance is 21.04 m.The first weighting step distance after pre-splitting blasting is 31.6 m,and the periodic weighting step distance is 14.6 m.Combined with the engineering geological conditions,the pre-splitting roof control scheme of thick and hard roof was designed,and the numerical simulation was carried out.The results show that after the pre-splitting blasting,the breaking step distance is effectively shortened,the peak stress of the working face is reduced by 21.46％-22.52％,and the influence of the advanced abutment pressure is effectively improved.The field monitoring data show that the effect of pre-splitting roof control is obvious,and the phenomenon of mine pressure appearance is effectively reduced.The research results can provide reference for pre-splitting and roof control of similar gob-side entry retaining working face.
Secondary miningThick and hard roofRoof cutting and pressure reliefPre-splitting blastingNumerical simulation
万方数据
维普
