Data Acquisition And Processing Of Micro-seismic Events

Micro-seismic monitoring technique has become one of the most effectiveapproaches to monitor the stability of rock mass in mines by a way of real time,on-line and remote observation, and however, the observed signal denoising, the onsettime picking and the seismic source locating are still the basic open problems forapplications of the technique. Considering the requirements for monitoring thestability of rock mass in Guilaizhuang Mine, Shandong Gold Mining Co., thedissertation has completed a systematic research to aim at solving these threeproblems by means of the developed micro-seismic monitoring system.(1) Considering nonstationary characteristics of the observed micro-seismic signals,this work proposes an approach to removing noises from the original signals on thebasis of the wavelet threshold method. After denoising by the proposed approach, theobtained signal maintains the consistency of wave peak positions with the originalwaveform, and it can fully preserves details of the sharp changes in the observedmicro-seismic waves. This approach may provide an effective technical support foridentifying and picking up the first arrival-time of the micro-seismic wave with higheraccuracy.(2) Applying the optimization method of function regression, this work suggests analgorithm for identifying and picking up the first arrival-time of the micro-seismicwave on the basis of the waveform. Comparisons with the picking time results, inthree cases of different sampling frequencies, time window widths and environmentnoises, show that the suggested algorithm of the first arrival-time picking has the goodpicking accuracy and an outstanding adaptability for applications. This conclusion isalso illustrated by the practice of the first arrival-time picking of the micro-seismicsignals observed in Guilaizhuang Mine.(3) The investigation results from locating the sources of micro-seismic eventsbased on the waveform characteristics show that the suggested approach in this workreduces the requirement of the sensor net arrangement and the sensor number forsignal acquisition, and effectively overcomes the fault of equivalent velocity modelunavailable for different transmission of the seismic waves along different directionsin the rock mass. The analysis based on blasting vibrations examines the accuracy ofsource locations resulted from the suggested approach of waveform location cansatisfies the requirement of mine micro-seismic monitoring technique.(4) Combined with the actual condition of Guilaizhuang Mine, this work develops amicro-seismic monitoring system, and designs a set of software matching with thissystem. Application shows that the system can realizes functions of the dataacquisition, parameter settings, and the data storage, to reaches the standard ofvisualizing the micro-seismic monitoring for the stability of rock mass in mines.