Experimental Study Of Seismic While Mining In Underground Coal Mines

Prospecting geology structure ahead of mining face is vital to safe and efficient coal mine excavation.But conventional underground coalmine exploration is carried out by detonating seismic charges,so its safety and efficiency is a problem.The underground coalmine seismic while mining technology(SWM)uses shearer or heading machine as seismic sources,no seismic charge or blast hole is needed,and doesn't interrupt production.Its survey-while-mining method has a unique advantage,and may open up a brand new survey mode in underground coalmine seismic exploration.By investigating the Vibroseis technology,Mini-Sosie technology,SWD(seismic while drilling)technology,shield machine source,and by summarizing the characteristics which the long-period seismic sources should have,suggested that the shearer or heading machine signals can be used as SWM sources.By analyzing the formation of country rock direct P wave,country rock direct S wave and channel wave,suggested the best receive method of SWM signal.Studied the process of SWM signal,including the pre-process of SWM data,the extraction of SWM signal,especially the frequency domain deconvolution interferometry method.Developed a program to eliminate the frequency dispersion and compress the wave train of SWM signal,providing possibilities for SWM velocity CT imaging in coal mine workface.The typical in-site experiments have proved the feasibility of SWM technique,and its application prospect is very cheerful.There are mainly these innovation points in this thesis.First,using SWM data,separated country rock direct P wave,country rock direct S wave and channel wave for the first time,and identified the reflection wave from roadway.This proved that the SWM source can replace the seismic charge source.Second,put forward the frequency dispersion elimination method for SWM data,and improved the S/N ratio of reflection wave that are formerly overwhelmed in dispersion wave train.This has laid a foundation for the coal mine workface velocity CT imaging.Third,put forward a coal seam thickness anomaly detection method based on the frequency dispersion elimination effect.This method can detect thickness anomaly low to 10%,which is very Sensitive.Research shows that using the mining machine as seismic source,SWM technique has its unique technical potential to replace seismic charge source and realize survey-while-mining dynamic forward prospecting.It may become the future direction of underground coal mine seismic exploration.