Research On Prediction Method Of Impact Risk In Fold Region Of Gaojiapu Coal Mine

Rock burst is one of the most typical dynamic disasters in coal mining.With the continuous increase of coal mining depth and mining intensity,rock burst phenomenon has become increasingly serious,which to some extent threatens the coal mine safety.Monitoring and early warning of rock burst can make a certain judgment on the possible occurrence of major dynamic disasters in coal mines,and make further corresponding disaster reduction measures,which is of great significance to coal mine safety,and a hot research field at present.Based on above,this paper uses deep analysis,data processing and engineering practice to study the characteristics of the precursor information of rock burst in fold area of the working face,and establishes the prediction method,which has been applied to the field practice and achieved good prediction results,of rock burst based on the characteristics of the mining tremor precursor in the fold region.Based on the seismic data of 204 working face of Gaojiapu Coal Mine,the paper summarizes the spatial and temporal evolution law of mining tremor events in the mining process of the working face of Gaojiapu Coal Mine,determines the distribution range of mining tremor events in different mining stages and the relative position relationship with the main key layer of the roof,counts and analyzes the influence scope of mining advance of working face and roof and floor,determines the stable time of mining tremor activity in goaf,analyzes the time sequence characteristics of mining tremor activity in working face,and the relationship between the advancing speed of working face and mining tremor activity,determines the critical propulsion speed.This paper analyzes the related factors of dangerous mining tremors in working face,and studies the characteristics and the influencing factors of dangerous mining tremors.The main factors of rock burst in Gaojiapu Coal Mine are mining speed,mining area,periodic weighting,fold region etc.Among them,the fold region has a great influence on the occurrence of mining tremor.When the working face approaches to the Syncline area,the disturbance of mining stress to the high stress concentration area increases gradually.With the advance of the working face,the mining tremor energy increases gradually,and the mining tremor frequency presents a state of"low frequency and high energy".The mining area of the fold region has a great influence on mining tremors,and the distribution of mining tremor is quite different from other mining areas of the working face.Within 250 meters before and after the syncline axis,the closer to the syncline axis,the higher the energy and frequency of mining tremor,and the farther away from the syncline axis,the lower the energy and frequency of mining tremor.This paper analyzes the precursory characteristics of rock burst in fold region of 204 working face in Gaojiapu Coal Mine,mainly analyzes the distribution law of mining tremors two months before the rock burst in Gaojiapu Coal Mine.One month before the rock burst event,the fluctuation of energy and frequency is small,however,it increases rapidly one week before the event.The trend of energy change presents a"?"shape one week before the event,and a"/"shape of frequency change.The energy peak value appears earlier than the frequency peak value.Two weeks before the rock burst event,the mining tremor has an obvious fluctuation.One day before the rock burst event,the overall trend of energy presented a"W"shape,and showed a state of"high frequency and low energy",while in the rest of the time,it showed a state of"high energy and low frequency".Finally,the quantitative analysis of the mining tremor data one week before the impact event is carried out,and four corresponding precursory response indexes of mining tremor are obtained:dynamic change rate of mining tremor energy N_E,dynamic change rate of mining tremor frequency N_P,deviation value of mining tremor energy D_E,deviation value of mining tremor frequency D_P.Based on the evolution law and the precursory characteristics of mining tremor in the fold areas of working face,a prediction method of rock burst risk based on deviation value and dynamic change rate as indexes is established,and the effect of this method is verified in 205 working face of Gaojiapu coal mine.The results show that the prediction effect of this method is well,and the prediction accuracy rate is 71%.There are 55 pictures,14 tables and 82 references in this paper.