Study On Monitoring And Prediction Of Seismicity And Rockburst In A Deep Mine

The prediction and control of rock burst in deep mine are the major theorical and technological task for safety of mining. The prediction of rockburst in the stage of mining design and rockburst monitoring during mining are the important methods of effectively controlling rock burst or reducing its hazard. But in this field, there are many problems that need to be studied. The prediction of proneness of rock burst, establishion of monitoring system of rock burst, the characteristics of mining-induced seismicity and prediction of hazard seismicity and rock bursts in Dongguashan Mine are studied in this paper, combined with the the fifteenth national key scientific subject "study on the key technology of safely and highly effective mining of deep copper deposit with the complex and difficult mining conditions". The major contents and results of this study are as follows:1. The research of rockburst prediction is carried out at the stage of minig design. The concept of residual energy index and its formula of calcualation and mensurement are put forward on the basis of the theoretical analysis and experiments of of deformation and fealure of rock of Dongguashan Mine. It is demonstrated that the index is more suitable to show proneness of rock burst. Experiments of acoustic emission of typical rock specimens of the mine are carried out. Consequently, the modes of acoustic emission are suggested for the prediction of rockburst proneness. Rockburst proneness of rock under the condition of mining is prodicted by numerical simulation and site rock burst investigation. The charateristics of spatial distribution of the proneness of rockbursts under the conditions of mining in Dongguashan Mine are predicted comprehensively by the results of numerical simulation, site investigation, experiments and spatial distribution of strata in this mine.2. The research of the monitoring system of rockburst in Gongguashan Mine is carried out. The system is demonstrated in terms of geologic conditions of mining, the results of rockburst prediction, and performance and applicability of mine safe monitoring system. The network of monitoring stations of Gongguashan Mine is optimized. The Gongguashan Mine rock burst monitoring system is established as an advanced monitoring means in Dongguashan Mine and a firm foundation for research of rockburst. Morphological characteristics and spectrum signatures of underground vibration signals of Dongguashan Mine are analyed. Methods of picking up arrival time of seismic signals are studied to improve the accuracy of recognition of seismic signal and precision of location of seismic events.3. By the analyses of spatial-time distribution of hypocenters, apprent stress, and displacement of seismic events, the charactheristics of space-time-intensity of mining-induced seismicity and the seismic response to mining are studied with the data of seismicity in Dongguashan Mine, in which some relationships between seismicity and size and property of excavation are discovered. A conceptual model and the criterion of estimation of hazard seismic nucleation are proposed for Dongguashan Mine according to the conditions of this Mine, which provide a theory and method for the locattion of areas of hazardous seismicity and rockburst in the mine.4. A mine seismic stiffness method of rockburst prodiction is proposed on the basis of the unstable failure theories, mine stiffness theories and the analyses of rock failure cases in Donggauashan Mine. The variable rate of ratia of stiffness of rock massive in nucleation area to its surrounding rock's is used as a criterion of rockburst prediction. The probability of suage of rock acoustic emssion in short-term prediction of rockburst is studied. The characteristics of time series of some seismic parameters and their precursors of rockburst are analyzed with theories of rock failure and seismology.5. Fractal demensions of spatial distribution of hypocenters of seismic events are calculated with general correlative integral, and as a result, characteristics of multifractal are analyzed. Fractal demension of spatial distribution of hypocenters of seismic events in a same spatial area during different time domain is computed. According to the result, the probability of usage of time series of fractal dimension in prediction of seismic hazard is discussed. On the basis of relation between the rate of seismic events and magnitude, fractal dimensions of seismic energy are calculated, and as a result, the relationship between the fractal of seismicity and seismic mechanism and mining activity is studied.