Dispersion features of transmitted channel waves and inversion of coal seam thickness

Hu, Zean; Zhang, Pingsong; Xu, Guangli

doi:10.1007/s11600-018-0192-4

Cited by 14 publications

(3 citation statements)

References 23 publications

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“…Therefore, the coal seam can be regarded as a typical lowspeed interlayer, comparable to a beam wave guide [11]. Once a longitudinal/transverse wave is excited in the coal seam, part of the excited energy undergoes repeated total reflections in the said interface as the wave propagates through the coal seam [12].…”

Section: Formation Mechanismmentioning

confidence: 99%

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

Sun¹,

Qi²,

Tian³

et al. 2021

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This paper mainly analyzes the typical geological structure of the coal seam with scouring zone, and examines the channel features of the coal seam. Firstly, a detailed analysis was conducted on the propagation features of channel wave in complex coal seam with geological anomalies. Based on COMSOL Multiphysics, a three-dimensional (3D) medium geometry model was established for complex coal seam with scouring zone. Relying on the model, channel wave propagation was simulated by finite-element method, and the propagation features were analyzed thoroughly. The Ricker wavelet with a central frequency of 200Hz was employed to emulate the explosive source, and the excited vibration signal was measured along the coal seam. Experimental results show that the longer the propagation distance of the channel wave signal in the coal seam, the more stretched the channel wave train, and the later the arrival of the maximum envelope of the wave train. The maximum envelope of the wave train appeared earlier in the model with the scouring zone than in the model without the scouring zone. After the channel wave passed through the scouring zone, the maximum envelope of the wave train appeared later in the model with the scouring zone than in the model without the scouring zone.

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Section: Formation Mechanismmentioning

confidence: 99%

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

Sun¹,

Qi²,

Tian³

et al. 2021

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“…As a dispersion parameter, we obtain frequency‐dependent group velocity, which is the velocity of wave transport. Measurement of group velocity from guided wave signals and inversion of the data deliver seam structure, which is crucial for the safety of underground mining (Dresen & Ruter, 1994; Liu et al., 1994; Hu et al., 2018; Zhu et al., 2019). The measurement of observed group velocity is generally performed through multiple filtering and time–frequency analysis (Bhattacharya, 1983; Cox & Mason, 1988).…”

Section: Introductionmentioning

confidence: 99%

Dispersion computation of guided waves in a layered transversely isotropic elastic medium sandwiched between two half‐spaces

Bhattacharya

2023

Geophysical Prospecting

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A transversely isotropic (TI) elastic medium with vertical axis of symmetry (VTI) is considered. We obtain dispersion equations in real terms for guided Love and Rayleigh waves in a VTI medium consisting of horizontal layers sandwiched between two half‐spaces by brief modifications of the available literatures on dispersion equations in elastic layered media through transfer matrix. To illustrate the applicability, dispersion curves of guided waves are computed for 3‐layered and 5‐layered symmetric models with a VTI coal seam in the middle. Airy phase is marked by a minimum or maximum of group velocity in a dispersion curve and this phase is important to get seam structure for mining safety. For the first 3 modes, the effect of VTI Thomsen parameters γ, ε and δ of a coal seam on frequency (fA) and group velocity (UA) of Airy phase is similar in 3‐ and 5‐layered models. For guided Love waves, fA and UA have nearly an uniform increase with increase of γ. For guided Rayleigh waves, increase of ε causes fA and UA to increase; while increase of δ causes fA and UA to decrease.This article is protected by copyright. All rights reserved

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“…Hence, precise prediction of coal thickness and of hidden geological anomalies in the working face is fundamental to realization of intelligent and unmanned mining. This is also directly related to the transformation of the whole process, and to the safety of underground workers [3].…”

Section: Introductionmentioning

confidence: 99%

Precise Identification of Coal Thickness by Channel Wave Based on a Hybrid Algorithm

et al. 2019

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Precise prediction of coal thickness is of the utmost importance in realizing intelligent and unmanned mining. As the channel wave is characterized by an easily recognizable waveform, a long propagation distance, and strong energy, it is widely used for coal thickness inversion. However, most traditional inversion methods are local in nature, and the inversion result is probably not optimal in the global scope. This paper introduces the GA-SIRT hybrid approach, which combines Genetic Algorithms (GA) and Simultaneous Iterative Reconstructive Techniques (SIRT) in order to deal with the above problem and to improve the accuracy of coal thickness inversion. The proposed model takes full advantage of the strong global search capability of GA and of the fast local convergence rate of the SIRT. Moreover, it inhibits the poor local search ability and the local optimal value effect of the GA and the SIRT respectively. The application of the GA-SIRT in the Guoerzhuang coal mine has significantly enhanced its accuracy, stability, and overall computational efficiency. Hence, the introduced novel hybrid model can precisely resolve and identify the coal thickness according to the channel wave. It can also be extended to other geophysical tomographic inversion problems towards the reduction of potential local optimal solutions.

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Dispersion features of transmitted channel waves and inversion of coal seam thickness

Cited by 14 publications

References 23 publications

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

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

Dispersion computation of guided waves in a layered transversely isotropic elastic medium sandwiched between two half‐spaces

Precise Identification of Coal Thickness by Channel Wave Based on a Hybrid Algorithm

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