Prediction of coal face rockbursts and microseismicity in deep longwall coal mining

Fujii, Yoshiyuki; Ishijima, Yoji; Deguchi, Gota

doi:10.1016/s1365-1609(97)80035-4

Cited by 53 publications

(15 citation statements)

References 4 publications

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“…The first approach can be traced back to the 1990s, where an evaluation index was introduced to estimate the microseismicity potential at all the grid blocks in the model domain representing an isotropic medium. Fujii et al (1997) used the total maximum shear seismic moment of fractured elements during one mining step as the indicator in three coal mining case studies, and successfully predicted burst-susceptible areas, and even rockburst occurrences. Nazimko and Babenko (2011) proposed an empirical criterion comprising of equivalent stress and stress relaxation rate, in order to account for dynamic failure of rock mass effectively.…”

Section: Advances In Modelling Of Seismic Activities In Rock Formationsmentioning

confidence: 99%

Numerical modelling of microseismicity associated with longwall coal mining

Cao

Shi

et al. 2018

International Journal of Coal Geology

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A B S T R A C TMicroseismicity has long been a precursor for underground mining hazards such as rockbursts and coal and gas outbursts. In this research, a methodology combining deterministic stress and failure analysis and stochastic fracture slip evaluation, based upon the widely accepted fracture slip seismicity-generation mechanism, has been developed to simulate microseismic events induced by longwall mining. Using the built-in DFN facility in FLAC 3D, discrete fractures following a power law size distribution are distributed throughout a 3D continuum model in a probabilistic way to account for the stochastic nature of microseismicity. The DFN-based modelling approach developed was adopted to simulate the evolution of microseismicity induced by the progressive face advance in a longwall top coal caving (LTCC) panel at Coal Mine Velenje, Slovenia. At each excavation step, global stress and failure analysis with reference to the strain-softening post-failure behaviour characteristic of coal, and fracture slip evaluation for microseismicity are conducted sequentially. The model findings are compared to the microseismic event data recorded during a long-term field monitoring campaign conducted at the same LTCC panel. It was found that the released energy and frequency-magnitude distribution of microseismicity are associated with the slipped fracture sizes and fracture size distribution. These features for recorded microseismic events were fairly constant until a xylite rich heterogeneous zone ahead of the working face was approached, which indicates that fractures within the extracted coal seam follow the same size distribution. The features obtained from modelled microseismic events were consistent over the production period, and matched well the field observations. Furthermore, the model results indicate that the power law fracture size distribution can be used to model longwall-mining-induced microseismicity. This model provides a unique prospective to understand longwall coal mining-induced microseismicity and lays a foundation to predict microseismicity, or even rockburst potential in specific geological realisations.

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Section: Advances In Modelling Of Seismic Activities In Rock Formationsmentioning

confidence: 99%

Numerical modelling of microseismicity associated with longwall coal mining

Cao

Shi

et al. 2018

International Journal of Coal Geology

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“…In recent years, and with the improvement of monitoring and interpretation techniques, microseismic monitoring has been accepted as a standard approach to understand and predict rock bursts in coal mines (Fujii et al, 1997;Kabiesz and Makówka, 2009;Lu et al, 2013;Cai et al 2014). Li et al (2007) suggested that rock bursts might induce high gas emission in underground coal mining.…”

Section: Introductionmentioning

confidence: 99%

Seismic monitoring and analysis of excessive gas emissions in heterogeneous coal seams

Durucan

Jamnikar

et al. 2015

International Journal of Coal Geology

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Uncontrolled and excessive gas emissions pose a serious threat to safety in underground coal mining. In a recently completed research project, a suite of monitoring techniques were employed to assess the dynamic response of the coal seam being mined to longwall face advance at Coal Mine Velenje in Slovenia. Together with continuous monitoring of gas emissions, two seismic tomography measurement campaigns and a microseismic monitoring programme were implemented at one longwall top coal caving panel. Over 2,000 microseismic events were recorded during a period of four months. Over the same period, there also was a recorded episode of relatively high gas emission in the same longwall district. In this paper, a detailed analysis of the processed microseismic data collected during the same monitoring period is presented. Specifically, the analysis includes the spatial distribution of the microseismic events with respect to the longwall face advance, the magnitude of the energy released per week and its temporal evolution. Examination of the spatial distribution of the recorded microseismic events has shown that most of the microseismic activity occurred ahead of the advancing face. Furthermore, the analysis of the gas emission and microseismic monitoring data has suggested that there is a direct correlation between microseismicity and gas emission rate, and that gas emission rate tends to reach a peak when seismic energy increases dramatically. It is believed that localised stress concentration over a relatively strong xylite-rich zone and its eventual failure, which was also identified by the seismic tomography measurements, may have triggered the heightened microseismic activity and the excessive gas emission episode experienced at the longwall panel monitored.

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“…It is the combined effect of geological environment, geological structures, geostresses, rock structures, physical and mechanical properties. It is a complicated process involving many factors [1][2][3][4][5][6][7][8][9][10][11][12]. The process and mechanism of dynamic mining disasters are related to numerous scientific problems.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of mechanisms of deformation, failure and energy dissipation in porous rock media subjected to wave stresses

Wang

Yang

et al. 2010

Sci. China Technol. Sci.

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The pore characteristics, mineral compositions, physical and mechanical properties of the subarkose sandstones were acquired by means of CT scan, X-ray diffraction and physical tests. A few physical models possessing the same pore characteristics and matrix properties but different porosities compared to the natural sandstones were developed. The 3D finite element models of the rock media with varied porosities were established based on the CT image processing of the physical models and the MIMICS software platform. The failure processes of the porous rock media loaded by the split Hopkinson pressure bar (SHPB) were simulated by satisfying the elastic wave propagation theory. The dynamic responses, stress transition, deformation and failure mechanisms of the porous rock media subjected to the wave stresses were analyzed. It is shown that an explicit and quantitative analysis of the stress, strain and deformation and failure mechanisms of porous rocks under the wave stresses can be achieved by using the developed 3D finite element models. With applied wave stresses of certain amplitude and velocity, no evident pore deformation was observed for the rock media with a porosity less than 15%. The deformation is dominantly the combination of microplasticity (shear strain), cracking (tensile strain) of matrix and coalescence of the cracked regions around pores. Shear stresses lead to microplasticity, while tensile stresses result in cracking of the matrix. Cracking and coalescence of the matrix elements in the neighborhood of pores resulted from the high transverse tensile stress or tensile strain which exceeded the threshold values. The simulation results of stress wave propagation, deformation and failure mechanisms and energy dissipation in porous rock media were in good agreement with the physical tests. The present study provides a reference for analyzing the intrinsic mechanisms of the complex dynamic response, stress transit mode, deformation and failure mechanisms and the disaster mechanisms of rock media. porous media, three-dimensional finite element model, rock media, stress wave, failure mechanism, energy dissipation Citation: JU Y, Wang H J, Yang Y M, et al. Numerical simulation of mechanisms of deformation, failure and energy dissipation in porous rock media subjected to wave stresses.

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Prediction of coal face rockbursts and microseismicity in deep longwall coal mining

Cited by 53 publications

References 4 publications

Numerical modelling of microseismicity associated with longwall coal mining

Numerical modelling of microseismicity associated with longwall coal mining

Seismic monitoring and analysis of excessive gas emissions in heterogeneous coal seams

Numerical simulation of mechanisms of deformation, failure and energy dissipation in porous rock media subjected to wave stresses

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