Study On Mechanism And Prevention Technology Of Rockburst Induced By Fault Activation In Mining Environment

With the coal mining gradually entering the deep stage,the rock burst disaster is very unfavorable to the safety production of the coal mine,and when the work is faced with mining near the fault area,the mining impact is easy to make the fault unlock and activate,and the rock burst is more likely to occur.In this paper,theoretical analysis,numerical modeling and field engineering practice are used as the main means to analyze the mechanism of fault activation and impact under mining conditions,and based on the theoretical guidance,the corresponding field prevention and control technology is obtained,and the following research results are obtained:(1)Based on Mohr Coulomb theory,the stress state of fault plane is analyzed,and the formula of limit equilibrium state of fault plane is derived by mathematical formula.It is found that the fault activation and instability is the result of a combination of many factors,the main factors are the nature of the fault itself and mining technology,including fault dip angle,fault type,fault formation time,fault drop,working face layout,mining depth,etc.(2)The limit friction factor is introduced to compare the fault friction factor with the limit friction factor,and the instability criterion of fault activation is obtained.The fault in the limit equilibrium state is not a stable fault,and the limit equilibrium state belongs to the unsteady equilibrium state.The mining environment is easy to break it,so that the fault is activated and unstable,resulting in rock burst.(3)Based on the engineering background,the FLAC3D model is used to solve the excavation problem.It is found that in the mining environment,the activation process of fault is not the whole fault at the same time,which has certain spatiotemporal characteristics.The activation instability state and activation time of fault in different horizons are different,generally from small activation instability to most activation instability.(4)According to the analysis of the displacement of the monitoring points set on the fault plane,it is found that the sensitivity of the displacement response of the fault plane is different in different layers,the priority of fault activation gradually increases from the upper part to the lower part of the fault,and the degree of fault activation instability is also related to the distance between the working face and the fault(affected by mining).(5)When the 3306 work faces the DF60 fault for mining,the theoretical and field monitoring data analysis show that the probability of rockburst is high in this process,so the method of "fault protection coal pillar" is adopted to prevent the occurrence of rockburst.According to the analysis of stress and energy of coal pillar by numerical simulation,the size of fault protection coal pillar is determined to be 120m.