scholarly journals Propagation Features of Channel Wave Signal in Coal Seam with Scouring Zone

2021 ◽  
Vol 38 (4) ◽  
pp. 1149-1160
Author(s):  
Hongyu Sun ◽  
Yuerui Qi ◽  
Wenlei Tian ◽  
Geng Chen ◽  
Yana Wang
Keyword(s):  
Coal Seam ◽  
Wave Signal ◽  
Channel Wave

Recognition of Coal Seam Channel Wave Signal based on SVM Multi-classifier

2021 ◽  
Author(s):  
Hongyu Sun ◽  
Die Zhang ◽  
Ao Wang ◽  
Song Wang ◽  
Dong Han ◽  
...  
Keyword(s):  
Coal Seam ◽  
Wave Signal ◽  
Channel Wave

scholarly journals Diffraction Characteristics of Small Fault ahead of tunnel face in coal roadway

2017 ◽  
Vol 21 (2) ◽  
pp. 95-99 ◽  
Author(s):  
Bo Wang ◽  
Shengdong Liu ◽  
Fubao Zhou ◽  
Jun Zhang ◽  
Fangkun Zheng
Keyword(s):  
Acoustic Wave ◽  
Coal Seam ◽  
Fault Prediction ◽  
P Wave ◽  
Mine Safety ◽  
Observation System ◽  
Tunnel Face ◽  
Coal Roadway ◽  
Small Fault ◽  
Channel Wave

Small fault ahead of the tunnel face in coal roadway is the important hidden hazard factor of coal and gas outburst accidents. The study of small fault prediction has important practical significance, which is the urgent demand of coal mine safety production. The diffraction of breakpoint can be used to identify the fault. However, unlike surface seismic exploration, the diffraction is with approximately horizontal incidence when the advanced detection is carried out in the roadway. The common advanced detection system is mainly as the reference of traffic tunnel, without considering the influence of low-velocity coal seam. Considering the influence of an acoustic wave of the roadway cavity and channel wave of the coal seam, the advanced detection model of small fault ahead of tunnel face is established. Diffraction advanced observation system in which sources located in front of tunnel face is constructed, and the numerical calculation of the high-order staggered-grid finite difference is carried out. The simulation results show that: Compared with the data collected by reflection observation system, in seismic records acquired by diffraction observation system, the suppression effect of acoustic wave is appeared. The diffracted P-wave of the breakpoint of component X is clear with strong energy and short-wave group. Multiple diffractions of the breakpoint are not found, but the multiple diffraction of tunnel face endpoint is obvious. The difference between breakpoint diffraction and multiple diffractions of the endpoint is clear, and diffracted P-wave of the breakpoint is easy to identify. The multiple reflected channel wave between the fault and the tunnel face is very obvious, and the reflected channel wave of small fault is so hard to identify. Migration results show that the imaging resolution of diffracted P-wave of small fault is higher than the reflected channel wave, and breakpoint location of imaging is consistent with the actual model.

scholarly journals A Theoretical Investigation of Channel Wave Multipath Propagation in a Coal Seam

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Yinjing Guo ◽  
Jianhua Zhang ◽  
Yuanyuan Ju ◽  
Xiaohan Guo
Keyword(s):  
Coal Seam ◽  
Time Delays ◽  
Multipath Propagation ◽  
Multipath Fading ◽  
Wave Pattern ◽  
Good Match ◽  
Multipath Fading Channel ◽  
Proposed Model ◽  
Channel Wave ◽  
Constant Distance

This study investigates the mechanism of channel wave multipath propagation to determine features of a channel wave in a coal seam. For this purpose, deduction formulas were used for different time delays and propagation paths and, subsequently, a multipath fading channel wave pattern was built. MATLAB software was used to simulate the model. To this end, the characteristics of the coal seam and the surrounding rock were considered. The simulation results were compared with results obtained from the model contained in COMSOL software to verify the accuracy of the model. According to the results obtained from the simulation, the proposed model shows a good match with the COMSOL model, which is a common simulation comparison standard. In addition, the channel wave energy approximates to exponential decay at a constant distance from the source, and the multipath propagation considerably affects its energy attenuation. Furthermore, the multipath reflections’ travel time derivation is accomplished properly in the coal seam.

Frequency‐dependent Q‐estimation of Love‐type channel waves and the application of Q‐correction to seismograms

Geophysics ◽  
1995 ◽  
Vol 60 (6) ◽  
pp. 1773-1789 ◽  
Author(s):  
Xiao‐Ping Li ◽  
Wolfgang Schott ◽  
Horst Rüter
Keyword(s):  
Dispersion Relation ◽  
Coal Seam ◽  
Quality Factor ◽  
Wave Energy ◽  
Nonlinear Function ◽  
Ratio Method ◽  
Elastic Model ◽  
Quality Factors ◽  
Frequency Dependent ◽  
Channel Wave

We present the absorption dispersion relation of Love‐type channel waves for a simple, symmetric, homogenous, three‐layered, linear elastic model assuming that the quality factors of coal [Formula: see text] and country rock [Formula: see text] are constant. We introduce complex propagation functions into the known dispersion relation describing most of the properties of the Love‐ type channel waves. The complex dispersion relation is expanded into power series of [Formula: see text] [Formula: see text] and [Formula: see text] [Formula: see text] factor of the Love‐type channel wave). The real part of the ensuing dispersion relation gives the usual dispersion relation. The imaginary part yields the frequency relation between the quality factor of Love‐type channel waves and the constant quality factors of coal and rock. In this case, [Formula: see text] depends on the frequency because the phase velocity is a function of frequency. Therefore, the attenuation coefficient is a nonlinear function of frequency. The analysis of the analytical result shows that at high frequencies the Love‐type channel wave energy is completely propagating inside the coal seam, and hence its propagation is determined by the physical properties of the coal alone. As the frequency approaches zero, the Love‐type channel wave energy is completely propagating in the rock, since the thickness of the coal is small compared to the wavelength of the channel wave, and hence the channel wave does not “see” the coal seam. The spectral ratio method is used to estimate the frequency‐dependent quality factor [Formula: see text] of Love‐type channel waves. This technique is demonstrated by applying it first to synthetic data and then to data of a well‐designed transmission survey. Finally, we use the estimated [Formula: see text] to derive an inverse Q‐operator and apply it for Q‐correction to both data sets.

Characteristics of transmitting channel wave in a coal seam

2009 ◽  
Vol 19 (3) ◽  
pp. 331-336 ◽  
Author(s):  
Zhen YANG ◽  
Mao-chen GE ◽  
Shu-gang WANG
Keyword(s):  
Coal Seam ◽  
Channel Wave

Coal seam mapping by analysis of direct channel wave arrivals

1987 ◽  
Vol 24 (4-5) ◽  
pp. 421-427 ◽  
Author(s):  
P.J. Hatherly ◽  
P. Hornby ◽  
P.F. Irwin
Keyword(s):  
Coal Seam ◽  
Direct Channel ◽  
Channel Wave

Wave Field Characteristics of Small Faults around the Loose Circle of Rock Surrounding a Coal Roadway

2020 ◽  
Vol 25 (2) ◽  
pp. 245-254 ◽  
Author(s):  
Bo Wang ◽  
Huachao Sun ◽  
Lanying Huang ◽  
Shengdong Liu ◽  
Biao Jin ◽  
...  
Keyword(s):  
Coal Seam ◽  
Wave Field ◽  
Love Wave ◽  
The Body ◽  
Body Waves ◽  
Seismic Record ◽  
Coal Roadway ◽  
Geological Conditions ◽  
Small Fault ◽  
Channel Wave

The geological conditions of coal roadway excavation are complicated. Seismic advanced detection is strongly influenced by the loose circle of fractured rock surrounding the competent coal seam. However, the three-dimensional wave field characteristics of small fault advanced detection in the condition of the loose circle of coal roadway have not examined. In this paper, numerical modeling and field tests were conducted to address this knowledge gap. The results indicate that when a seismic source near the tunnel face is excited, the body waves and a Love channel wave propagate in the tunneling direction toward the small fault, then produces reflected body waves whose amplitude is relatively weak, and a reflected Love channel wave whose amplitude is relatively strong. When reflected body waves and the reflected Love channel wave enter the loose circle of surrounding rock, the former's signal is unrecognizable in seismic record; but the latter converts to a Love wave whose amplitude is strong in the loose circle of coal seam. The Love wave which has a large interval from other wave trains in the time domain is easily recognizable in seismic record, which makes it suitable for advanced detection of small fault. The signal-to-noise ratio of seismic record of X component is higher than those of Y component and Z component.

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