| At present,the gravity center of coal resource mining in our country is gradually tilting to the northwest mining area.Meanwhile,the tectonic movement is active in the northwest area,and the mining conditions of coal face fold are relatively developed.A large number of engineering practices show that the fold structure area is more likely to lead to roadway surrounding rock deformation and failure,and the probability of rock burst is higher.Since the prediction accuracy of rock burst in the fold area is not high,this thesis analyzes the surrounding rock stress in the fold area,studies the distribution characteristics of large energy microseismic events in the fold area,and determines the monitoring and warning index of rock burst in the fold area through in-situ observation and identification,aiming at the monitoring and warning problem of rock burst in the fold area faced by the mining under the condition of fold structure.The multi-dimensional information fusion monitoring and early warning model of microseismic in the fold area is established,which finally provides a theoretical basis for monitoring and early warning of mining in the fold area.The stress state of different parts of fold is analyzed theoretically and the stress distribution of roadway surrounding rock in fold area is studied by constructing high simulation numerical model of Cuimu Coal mine.Based on the analysis of the microseismic data,the distribution characteristics of the large energy microseismic events in the working face and roadway in the fold area are obtained:(1)The large energy microseismic events are basically distributed in the B2 anticline axis and the garden slope syncline axis.(2)Periodic aggregation and distribution of large energy microseismic events;(3)The maximum daily microseismic energy of 22303 working face is consistent with the total daily microseismic energy,but the frequency of microseismic events and large energy events cannot maintain a good consistency,so the early warning accuracy is low only from the perspective of frequency changes.Based on the mechanical basis of rockburst early warning,through in-situ observation and identification,it is found that different indexes are different in their sensitivity to rockburst in the fold area,and b value,lack of shock and Z-map value are more sensitive to the rockburst in the fold area.The value of A(b),total fault area A(t),microseismic activity S,and microseismic activity scale △F are more sensitive to the high value anomaly of rockburst in the fold area.Finally,the values of b,A(b),total fault area A(t),microseismic activity S,microseismic activity scale △F,lack of shock,and Z-map are selected as the indicators of the occurrence of rockburst and precursor information of strong mine shock events in the fold area.Through the example of impact danger warning,the shortcomings of rockburst danger prediction driven by microseismic index are analyzed.According to the reliability theory and the index standardization method,the monitoring and each early warning index dimensions are uniformly processed to make them consistent.For each warning level of microearthquake precursor index,the relative membership function was established by using Gaussian function.The weight of each index in the early warning model is calculated by the accuracy evaluation method of confusion matrix(F-score).Finally,the multi-dimensional information fusion monitoring and early warning model of rockburst microearthquakes in the fold area is obtained by applying the MMDP principle and VFPR principle.By using the microseismic data of 22303 working face of Cui Mu Coal Mine and Beiyi Roadway,it is found that the comprehensive monitoring and early warning model of fold area has good effect and high accuracy.Meanwhile,the engineering practice of the early warning of subsequent strong mine shock events in Beiyi Roadway is carried out,and the accuracy of early warning is 86.7%.This thesis has 76 pictures,16 tables,and 87 references. |
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