Characteristics of Valuable Microseismic Events in Heading Face of an Underground Coal Mine Using Microseismic System

Wenlong Zhang,Xiaocheng Qu,Chen Li,Tianhong Huo,Chongwei Xin,Cunwen Wang,Marta Berardengo

doi:10.1155/2021/6683238

Abstract

Rock burst monitoring of heading face is a weak aspect of rock burst monitoring in China; acoustic emission (AE) monitoring is one of the few monitoring technologies used in heading face, but its target signals are small energy events which are easy to be disturbed. Researchers usually focus on the weak AE events but ignore the microseismic (MS) events (different from AE event and caused by a larger scale of coal fracture), while this kind of events can also reflect the pressure situation of heading face and have higher energy value which may become a better indicator for rock burst monitoring of heading face. So, the basic characteristics of MS events in heading face are studied based on a running vibration signal acquisition system, including the occurrence position, main frequency range, maximum amplitude (MA) range, event duration, and relationship with geological structure. This paper provides a development basis of the monitoring method for rock burst monitoring of heading face by using MS events.

Highlights

Studies show that 40.74% occurred in heading face according to the counted 108 accidents of Yima ore district [18]. e monitoring technology of rock burst in working face has been relatively mature in China [19, 20]; the whole mine MS system can get the high-energy event caused by breaking of high-level roof [21]; the high-precision MS system can obtain the movement of low-level roof [22]; coal stress monitoring can reflect the change of advanced abutment pressure [23]
The geological structure is the place where rock burst occurs most frequently [51], which provides the possibility of using MS events as an indicator of rock burst monitoring and early warning in heading face
The basic characteristics of MS events which are different from acoustic emission (AE) events in heading face are obtained: maximum maximum amplitude (MA) value is 10258 mV; minimum and maximum values of main frequency are 14 Hz and 515 Hz, respectively; and maximum event duration is 1.78 s

Summary

Introduction

Rock burst is one of the most serious dynamic disasters in underground coal mines of China [1], which may be caused by certain dangerous stress [2, 3], specific characteristics of mining coal [4, 5], roof strata movement [6], or roadway layout [7, 8], and seriously affects the normal operation of coal mine [9]. e key to solve the problem of rock burst lies in clear mechanism [10], effective monitoring [11, 12], and control measures [13, 14]. E monitoring technology of rock burst in working face has been relatively mature in China [19, 20]; the whole mine MS system can get the high-energy event caused by breaking of high-level roof [21]; the high-precision MS system can obtain the movement of low-level roof [22]; coal stress monitoring can reflect the change of advanced abutment pressure [23]. The rock burst monitoring of heading face is not mature, and the difficulties mainly lie in the following four points: (1) the influence range of excavation is small [24], but the disaster degree is not low [25]; (2) the construction environment is complex, and the construction machineries bring trouble to the effective acquisition [26]; (3) the sensor layout conditions of heading face are limited, which can only be placed in the roadway and cannot spread out; and (4) the excavate speed is fast, about 7 m–10 m every day for comprehensive excavation face and about 20 m–30 m every day for continuous mining face.

Objectives

Results

Conclusion