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《Chinese Journal of Rock Mechanics and Engineering》 2011-10
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MATHEMATICAL FUNCTIONS AND PARAMETERS FOR MICROSEISMIC SOURCE LOCATION WITHOUT PRE-MEASURING SPEED

DONG Longjun,LI Xibing,TANG Lizhong,GONG Fengqiang(School of Resources and Safety Engineering,Central South University,Changsha,Hunan 410083,China)  
To eliminate the locating error for microseismic monitoring system due to the speed measurement deviation,three innovative nonlinear methods of multi-robe locating were proposed.According to different dependent variables,the source location methods of trigger times(TT),time difference(TD),and time difference quotient(TDQ) were proposed.The two traditional location methods with dependent variables of speed and trigger times(STT),and speed and time difference(STD) were discussed.Firstly,virtual position tests,by the two new methods TT and TD and the traditional methods STT and STD in the floating rate of error at 0,1%,2%,3%,4% and 5% of the real sonic speed,were carried out using 8 sensors,respectively.The errors from two new and traditional methods were compared and analyzed.Results show that the errors of the absolute distance are 0–1.01339 and 0.01–0.014 m from new methods TT and TD without using speed;they are almost close to the 0–0.981 m from traditional methods STT and STD using real speed.However,it is very difficult to measure the speed in practice.There are more or less a certain measurement deviations,and we almost do not know its real value.Therefore,we consider the speed with a smaller error rates of 1%–5% floating,and they resulted in larger errors of source coordinate position;and the larger is up to 24.27 m.Secondly,with the signal of blasting effect as simulation source,the blasting experiments were carried out in Dongguashan copper mine;a deep-level mine in China.The results obtained by the innovative nonlinear methods TT and TD of multi-robe locating were compared with that by traditional methods STT and STD.It was proved that this new nonlinear method TD not only has better locating precision,but also it is more convenient than traditional method.To locate the seismic source by the new nonlinear method,only the times when the signals arrive at the probes need to be measured using the threshold crossing technique of the instrument;and the speed of the propagation medium needs no measurement.
【Fund】: 国家自然科学基金资助项目(10872218 50934006);; 国家重点基础研究发展计划(973)项目(2010CB732004)
【CateGory Index】: P315.7
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