Study On The Surrounding Rock Control Of The Comprehensive Caving Coal Mining In The Ultra-close Multiple-seams Coal Beneath Coal Pillar

The method of the comprehensive caving coal mining in theultra-close multiple-seams coal beneath coal pillar means that the fullymechanized top coal caving mining is used in the lower coal during face layoutin lower coal resources directly during the residual coal pillar is stopping as thetop coal after longwall pillar mining is used in the upper coal.the extraction ofthe upper coal seam and the concentrated stress by residual coal pillar makes theroof rock structure、mine pressure behavior、the relationship between supportand surrounding rockcontrol、auxiliary technical measures different for theextraction of the upper coal seam in the ultra-close multiple-seams coal.Espeacialy for the comprehensive caving coal mining in the ultra-closemultiple-seams coal beneath coal pillar, fully mechanized top coal cavingworking face roof will appear deformation and damage, prone to leakageaccident because of the existing coal pillar.The connect between the upper goaf with pillar and the working faceincreases the risk of the residual coal spontaneous combustion in goaf. Theaverage level of No.8and No.9coal seam of the distance is only0.75m in thewang feng coal mine. The method of the comprehensive caving coal mining inthe ultra-close multiple-seams coal beneath coal pillar is used in orderto more normal production of coal resource recovery continuation of mine.According to the background of the actual situation of wangfeng coalmining, No.8coal seam floor stability and residual distribution regularity ofcoal pillar stress, fully mechanized top coal caving mining overlying stratastructure characteristics are analysed through the field investigation, physical and mechanical parameters of surrounding rock test, theoretical analysis,numerical simulation and other methods，the main research contents are asfollows:1.The bearing strength and plastic zone of the residual coal pillar aredetermined and the stability of coal pillar is analyzed by the energy theory.2.The mechanical model of combined fully mechanized caving miningis established and the characteristics of overlying strata structure are analyzed.3.The reasonable working resistance of the joint fully mechanizedcaving mining is determined by analyzing the stress of the roof structure.4.The caving property of top coal caving mining is analyzed and theassistant technical measures are formulated..So the study on the structural characteristics and control of overlyingstrata of the comprehensive caving coal mining in the ultra-close multiple-seamscoal beneath coal pillar is meaningful for the continuation of the mineproduction and the extremely close distance coal seam miningtheory,meanwhile,it has certain the oretical and practical value.