Journal of University of Science and Technology Beijing
Volume 15, Number 3, June 2008, Page 215
Mineral
Corresponding author: Fenhua Ren, E-mail: renfh2001@sina.com Also available online at www.sciencedirect.com
© 2008 University of Science and Technology Beijing. All rights reserved.
Dynamic destabilization analysis based on AE experiment of
deep-seated, steep-inclined and extra-thick coal seam
Fenhua Ren
1)
, Xingping Lai
2)
, and Meifeng Cai
1)
1) School of Civil and Environment Engineering, University of Science and Technology Beijing, Beijing 100083, China
2) School of Energy and Resource, Xi’an University of Science and Technology, Xi’an 710054, China
(Received 2007-11-08)
Abstract: No. 5 coal seam in Huating Coal Mine is a deep-seated, steep-inclined extra-thick coal seam where excavation disturbance
is quite frequent. The maximum and minimum principal stresses differ widely. During mining, dynamical destabilization happens
frequently and induce tragedies. Based on the comparison between the acoustic emission (AE) experiment on dynamical destabiliza-
tion of coal rock and the related in situ testing results, this article provides comprehensive analysis on the regular quantificational AE
patterns (energy rate, total events) of coal rock destabilization in complex-variable environment. The comparison parameters include
dynamic tension energy rate, deformation resistance to compression, and shear stress.
© 2008 University of Science and Technology Beijing. All rights reserved.
Key words: coal seam; acoustic emission (AE); destabilization; excavation disturbance
[The work was financially supported by the National Natural Science Foundations of China (Nos. 10772144 and 10402033).]
1. Introduction
Owing to several differences in coal-rock fracture
and destabilization between deep-mining and shal-
low-mining, secure mining of deep-seated coal is still
a puzzle to the domestic and foreign mining industry
[1-2]. Huating Coal Mine is located in the western
zone of China with frequent earthquakes. The main
parameters of No.5 coal seam are: obliquity = 45º, av-
erage thickness = 51.51 m, mining depth = 819.45 m,
and rigidity parameter f = 1
-3. Roof-caving, collapse,
and concussion happen frequently. Around the main
faultage of the mine, stress concentration was dynam-
ically and intensively developed in rock mass around
the mined-out area and in the remaining coal pillars.
Excavation disturbance happens frequently, which is
liable to cause dynamical hazards during mining in
neighboring areas [3-5]. Based on a comprehensive in
situ investigation and comparison between indoor rock
mechanical experiment with AE measurement and in
situ investigation, the reasons and mechanical charac-
teristics of dynamical destabilization are discussed in
this article, which provides a basis for predicting the
possibility (or possible areas) of dynamical hazards
during mining and for controlling and eliminating ha-
zards.
2. Anomalous earthquakes and hazards in
Huating area
Since 2001, there are obvious phenomena of inten-
sified anomalous earthquakes in Huating area. The
primary characteristics are indicated by statistical
analysis in Figs. 1 and 2.
(1) The earthquakes converge in space. The earth-
quakes mainly occur in Huating County and Chongxin
County, and most of them occur within a small rec-
tangle area whose longitudinal length is 30 km and la-
titudinal length is 40 km.
(2) The earthquakes are low in seismic magnitude
but are quite frequent. Since October 2001, there have
been 717 earthquakes in Huating area, of which 48
had magnitude less than M
L
0.9 (M
L
is local magni-
tude), 243 had the magnitude between M
L
1.0-1.9, 391
had the magnitude between M
L
2.0-2.9, 33 had the