| Underground mining to open pit mine,the original mining area is the biggest hidden danger of mine production.Identification of the dangerous area of surrounding rock in goaf is the key to ensure safe and efficient production of mines.Based on this research background,the main work of this paper is as follows(four parts):(1)Research on noise reduction of surrounding rock microseismic data in goaf.Obtain the original data and denoise,classify the microseismic signals collected by the surrounding rock sensors in the empty area,identify 6 kinds of interference signals that affect the identification of the dangerous areas,and convert it into time-frequency graph with the synchronous extrusion wavelet transform,and carry out the wavelet base combination to reduce the noise of the different frequency bands.Choosing the appropriate Yoon-V adaptive threshold parameters to increase the flexibility of noise reduction.After comparing the effect of Yoon-V adaptive threshold denoising and traditional soft and hard threshold denoising,the T value method is used to evaluate the effect of noise reduction.(2)The study of the localization of the microseismic events in the surrounding rock of the goaf.Using noise reduction data to locate the surrounding rock in goaf.Field data extract wave velocity and focal point to the sensor’s travel time.The location data were located by linear location and linear-Geiger localization.Combined with the optimal D value placement of sensor and X,Y and Z three directions,the source error is compared,and the location error distribution is obtained.The location effect is evaluated to verify that the linear-Geiger method is superior to the linear location method so that the Geiger method is effective and accurate.(3)Study on the identification of a dangerous area of surrounding rock in goaf.The ratio of energy in the frequency range from 622.25Hz to 1080.75Hz in the range of 622.25Hz to 1080.75Hz is 70%and the critical value is 0.76754.(4)Engineering example.The noise reduction,location optimization and dangerous area identification of the air area microseismic monitoring data in the range of 5～19 and XVII to XJ in the D area are finally obtained.Finally,the distribution of the dangerous area in the D area between June 12,2017,and June 20th is obtained,and the effect of identifying the dangerous area with the occurrence rate of the microearthquake events and the field observation is further verified.In the process of frequency division noise reduction,it is found that the combination of small wave base and parameters corresponding to the specific waveform are different,and the adaptive threshold is obviously better than the soft and hard threshold.These conclusions have some value for the study of wavelet denoising.In the study of location method,linear-Geiger positioning is obviously better than linear positioning,and also provides theoretical support for engineering practice.For the division of dangerous areas in D area,when the ratio of energy in the frequency range from 622.25Hz to 1080.75Hz tends to be between 0.0303 and 0.76754,it is of moderate risk level,and the ratio is lower than 0.0303,which belongs to the case of low risk.Through the research of this subject,it is concluded that the combination of linear location and Geiger positioning can solve the problem of initial value selection very well.The method of finding the dangerous area by dividing frequency domain energy ratio has a certain effect. |
PDF Full Text Request