Deficiencies in 2D Simulation: A Comparative Study of 2D Versus 3D Simulation of Multi-seam Longwall Mining

Adhikary, Deepak; Khanal, Manoj; Jayasundara, Chandana T; Balusu, Rao

doi:10.1007/s00603-015-0842-7

Cited by 23 publications

(25 citation statements)

References 3 publications

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“…Further, the reliable prediction and management of mining-induced surface subsidence is one of the environmentally challenging issues in the context of coal mining (e.g., Adhikary et al [30]; Sury et al [9]). Luo et al [57] developed a UCG subsidence prediction methodology and showed that overlying strata and ground surface subsidence behavior in UCG operation is relatively similar to that in conventional longwall coal mining.…”

Section: Discussionmentioning

confidence: 99%

“…This state served as starting data set for all simulations carried out in the scope of the present study. In order not to overestimate ground surface subsidence and stresses in 3D models as discussed by Adhikary et al [30], UCG reactor growth is considered to occur simultaneously in 50-m steps along the pre-defined UCG channels, determined by an average gasification front progress of 1 m/day. The selected reactor growth rate is in good agreement with the empirical model presented by Najafi et al [12], allowing for predication of UCG reactor growth rates under various operational and geological boundary conditions.…”

Section: Numerical Model Geometry Parametrization and Boundary Condimentioning

confidence: 99%

“…Almost all previous UCG studies applied one-dimensional (1D) or two-dimensional (2D) models to account for selected coupled processes [10], which only have a limited validity in predicting the performance of UCG field trial operation, especially when considering the generally high heterogeneity and complexity of geological systems. For instance, it is known that 2D models may overestimate the magnitude of ground surface subsidence and stresses in pillars [30]. Consequently, three-dimensional (3D) numerical 3D models, representing known geological features in high details are required for reliable predictions of site-specific UCG performance.…”

Section: Introductionmentioning

confidence: 99%

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Fault Reactivation Can Generate Hydraulic Short Circuits in Underground Coal Gasification—New Insights from Regional-Scale Thermo-Mechanical 3D Modeling

et al. 2016

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Underground coal gasification (UCG) has the potential to increase worldwide coal reserves by utilization of coal deposits not mineable by conventional methods. This involves combusting coal in situ to produce a synthesis gas, applicable for electricity generation and chemical feedstock production. Three-dimensional (3D) thermo-mechanical models already significantly contribute to UCG design by process optimization and mitigation of the environmental footprint. We developed the first 3D UCG model based on real structural geological data to investigate the impacts of using isothermal and non-isothermal simulations, two different pillar widths and four varying regional stress regimes on the spatial changes in temperature and permeability, ground surface subsidence and fault reactivation. Our simulation results demonstrate that non-isothermal processes have to be considered in these assessments due to thermally-induced stresses. Furthermore, we demonstrate that permeability increase is limited to the close reactor vicinity, although the presence of previously undetected faults can introduce formation of hydraulic short circuits between single UCG channels over large distances. This requires particular consideration of potentially present sub-seismic faults in the exploration and site selection stages, since the required pillar widths may be easily underestimated in presence of faults with different orientations with respect to the regional stress regime.

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Section: Discussionmentioning

confidence: 99%

Section: Numerical Model Geometry Parametrization and Boundary Condimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fault Reactivation Can Generate Hydraulic Short Circuits in Underground Coal Gasification—New Insights from Regional-Scale Thermo-Mechanical 3D Modeling

et al. 2016

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“…Despite many examples of single‐seam subsidence, there are only a few examples of numerical modelling of multi‐seam subsidence in the literature. In fact, to the best knowledge of the authors, the only published works with reasonable details on numerical simulation of multi‐seam subsidence is limited to the works of .…”

Section: Previous Work On Numerical Modelling Of Multi‐seam Mining‐inmentioning

confidence: 99%

“…These methods include finite element method (FEM) [6][7][8][9][10][11], discrete/distinct element method [12,13], finite deference method [14,15], mesh free methods and user-defined damage models [16,17]. However, there are only a few examples of numerical modelling of multi-seam subsidence available in the literature [2,11,18,19]. Numerical modelling of multi-seam subsidence is inherently more complicated than single-seam subsidence.…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling of multistage caving processes: insights from multi‐seam longwall mining‐induced subsidence

Ghabraie

Ren

et al. 2016

Num Anal Meth Geomechanics

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Summary Evaluating the induced subsidence is a critical step in multi‐seam longwall mining. Numerical modelling can be a cost‐effective approach to this problem. Numerical evaluation of longwall mining‐induced subsidence is much more complicated when more than one seam is to be extracted. Only a few research works have dealt with this problem. This paper discusses the essential requirements of a robust numerical modelling approach to simulation of multi‐seam longwall mining‐induced subsidence. In light of these requirements, the previous works on this topic are critically reviewed. A simple yet robust FEM‐based modelling approach is also proposed that is capable of simulating caving process, rock mass deterioration and subsidence around multi‐seam excavations. The effectiveness of this approach in comparison with two other conventional FEM approaches is demonstrated through numerical examples of two different multi‐seam mining configurations. Results show that the proposed numerical modelling approach is the only robust method, which is capable of simulating multi‐seam subsidence in both demonstrated cases. Copyright © 2016 John Wiley & Sons, Ltd.

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Optimization of staggered distance of coal pillars in multiseam mining: Theoretical analysis and numerical simulation

Sun

Cheng³

2020

Energy Science & Engineering

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Aimed at solving problems related to water retention and loss reduction in multiseam mining, a mechanical model of staggered distance mining was established. First, elastic and plastic slip line field theories were used to calculate the reasonable staggered distance expressions of multiseam mining. The staggered distance schemes of multiseam mining were optimized using the numerical simulation software FLAC3D. By performing an experiment comparing similar materials, the influence on water retention and loss reduction by optimal and unfavorable staggered distance schemes in multiseam mining was explored. The results showed that the σzz curve was distributed in the shape of a “peak” of the staggering distance coal pillars, the Z displacement curve was a “Л,” and the surface subsidence curve was a “W.” Each of these displayed the rule of “decrease then increase.” In staggered distance multiseam mining, the optimal staggered distance value for coal seam Nos. 2 and 3 was 40 m, while the most unfavorable staggered distance value was 0 m. The corresponding subsidence coefficients of the optimal staggered distance values were 0.29, 0.23, and 0.19, under the condition of keeping the optimal staggered distance value for coal seam Nos. 1 and 2 unchanged. These results could be beneficial in reduction of surface subsidence and may also have specific practical engineering significance.

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Deficiencies in 2D Simulation: A Comparative Study of 2D Versus 3D Simulation of Multi-seam Longwall Mining

Cited by 23 publications

References 3 publications

Fault Reactivation Can Generate Hydraulic Short Circuits in Underground Coal Gasification—New Insights from Regional-Scale Thermo-Mechanical 3D Modeling

Fault Reactivation Can Generate Hydraulic Short Circuits in Underground Coal Gasification—New Insights from Regional-Scale Thermo-Mechanical 3D Modeling

Numerical modelling of multistage caving processes: insights from multi‐seam longwall mining‐induced subsidence

Optimization of staggered distance of coal pillars in multiseam mining: Theoretical analysis and numerical simulation

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