Study On Time-space Characteristics And Early Warning Model Of Microseismic Event Parameters In A Tungsten Mine

Due to the long mining life and the applicability of mining methods and other factors,a large number of mined out areas are formed in the mine after mining.If there is no effective monitoring and management of ground pressure in the process of mining activities,it is easy to lead to rock mass instability disaster.In order to reduce the hidden dangers of subsequent mining,the management of ground pressure activities must be the first problem to be solved.Microseismic monitoring,as a high-precision technology for monitoring micro cracks in rock mass,can monitor the initiation,development and expansion of micro cracks in rock mass under stress from three-dimensional space in real time.In this paper,based on a tungsten mine in South Jiangxi,a large number of microseismic events are collected by IMS microseismic monitoring system in South Africa,and the characteristics of ground pressure activity in the mine are studied,In view of the instability of rock mass in 21⁵#mining area during excavation,the activity of microseismic event is analyzed and the variation characteristics of microseismic parameters before the instability of rock mass are studied.The main research contents and achievements are as follows:（1）Based on the field investigation of ground pressure activities in the middle section of417 to 517 of a tungsten mine,the common manifestations of the areas with frequent ground pressure activities are cracking,deformation and bulging.（2）According to the current situation of mining and the area with violent ground pressure activity,a set of 33 channel microseismic monitoring system is established according to the principle of microseismic monitoring.Through the simulation of the minimum sensitivity and positioning accuracy of the designed points,the monitoring accuracy of the system is verified.Through the blasting test,P-wave 5344m/s and S-wave 3340m/s are obtained.The characteristics of several typical source signals are summarized by time-frequency analysis.（3）Analyze and collect the microseismic data,grasp the temporal and spatial distribution characteristics of microseismic events in the mine,and obtain the response relationship between microseismic events and mining activities.Using seismology and statistics to analyze the microseismic parameters before the instability of 21⁵#east third stope mining rock mass,the precursory law of microseismic parameters before the instability of rock mass is obtained.The monitoring results show that the rapid increase of cumulative apparent volume accumulation,the sharp decrease of logarithm energy index and Schmitt number indicate the deterioration trend of rock mass,and the rapid decrease of b value,the large increase of displacement and the decrease of apparent stress are all the precursors of ground pressure disaster.Combined with the theory of grey catastrophe,the instability of rock mass is judged.According to the time series of accumulated energy,the prediction model x?^（0）（k）=8.563e^0.36718k is established,which is verified in the field.（4）For the 21⁵#East Third mining with rock mass instability,Flac^3D is used to simulate the mining process of the stope,analyze the stress distribution and displacement concentration of the surrounding rock of the upper and lower walls and roof and floor during the mining process,and get the possible position of rock mass instability.At the same time,Vantage is used to analyze the cloud image in this area.The results show that the numerical simulation results are in good agreement with the microseismic monitoring results.