Study of automated top-coal caving in extra-thick coal seams using the continuum-discontinuum element method

Yue, Jinchao; Liu, Chuang; Feng, Chun; Li, Huamin

doi:10.1016/j.ijrmms.2019.04.019

Cited by 42 publications

(24 citation statements)

References 23 publications

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“…Based on the connecting bar model, the surface contact relationship between two particle elements is established. The equivalent contact area A c is the projected area of smaller particles, and A c is mainly used to calculate the contact stiffness between particle elements [17]. The contact stiffness parameters can be obtained by Equation (10):…”

Section: The Principle Of Progressive Failure Process Of Cdemmentioning

confidence: 99%

Numerical Damping Calibration Study of Particle Element Method-Based Dynamic Relaxation Approach for Modeling Longwall Top-Coal Caving

Wei-yu

et al. 2021

Energies

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When using the explicit dynamic relaxation approach (DRA) to model the quasi-static rock breakage, fragmentation, and flow problems, especially the top-coal caving question, introducing numerical damping into the solution equation is inevitable for reducing the vibration frequency and impact speed of mesh nodes, which is significantly affect the fidelity of the computation results. Although the DRA has been widely adopted to simulate top-coal caving, the reasonable value and calibration method of numerical damping are still open issues. In this study, the calibration process of reasonable numerical damping for modeling top-coal caving is investigated by comparing with the experimental results, in which several geometry parameters of the drawing funnel are selected as the calibration indexes. The result shows that the most reasonable numerical damping value is 0.07 for the numerical modeling of interval top-coal caving in extra-thick coal seams. Finally, the correlation between the numerical damping and the physical top-coal drawing process is discussed. The numerical damping indirectly reflects the fragmentation in multi scale of coal mass and friction interaction between coal particles during the caving process, which reduces the vibration intensity of the top-coal caving system and dissipates the kinetic energy.

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Section: The Principle Of Progressive Failure Process Of Cdemmentioning

confidence: 99%

Numerical Damping Calibration Study of Particle Element Method-Based Dynamic Relaxation Approach for Modeling Longwall Top-Coal Caving

Wei-yu

et al. 2021

Energies

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“…For the particle elements of the discontinuum element method, the linked bar model combined with the Mohr-Coulomb criterion and maximum tensile stress criterion is used to simulate the rock breaking and moving [30][31][32].…”

Section: Simulation Programmentioning

confidence: 99%

“…In general, the continuum mechanics method is suitable for analyzing the small deformation and damage behavior of materials, and the discrete element method can easily analyze the rock fracturing and motion. A continuum-discontinuum element method (CDEM) combines the advantages of the finite element method and the discrete element method, which has gradually become an effective simulation method to study the failure mechanisms of rock materials [27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Using Continuum-Discontinuum Element Method to Model the Foliation-Affected Fracturing in Rock Brazilian Test

Zhi

Feng

et al. 2021

Advances in Civil Engineering

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In this study, the continuum-discontinuum element method (CDEM) was used to investigate the tensile fracture mechanism of rock materials. An isotropic rock disk model and models considering different foliation inclinations were established, and three schemes were used to simulate the rock fracturing in Brazilian test. Then, the influences of the rock matrix and foliation strengths on anisotropy rock fracturing were investigated. Furtherly, simulation results were verified, and the rock fracture mechanisms were discussed. The results show that the rock fracturing in Brazilian test can be accurately simulated by CDEM, which is in accordance with the experimental results. For isotropic and horizontal foliation rock, the stress concentration in loading positions causes a local fracture of rock sample, and application of a local strengthening scheme can simulate the integral tension fracture of sample middle. As the foliation angle varies from 15° to 45°, the rock fracturing is affected by the stress concentration and foliation distribution. In splitting simulation, a strengthening scheme should be adopted to overcome this influence. As a result, the rock sample generates the sliding and compression-shear fracture. As the foliation angle changes from 45° to 75°, the foliation, rather than the matrix, dominates the fracture behavior of rock sample. For vertical foliations’ rock, as the middle foliation thickness is appropriately broadened, the simulation results are reasonable. In general, the tensile strength of anisotropic rock entirely decreases with an increase of foliation angle, and the effect of foliation strength on the tensile strength rock sample is larger than that of the rock matrix.

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“…CDEM also shows good application prospects in simulating top-coal caving. Zhang et al proposed a new CDEM model to study top-coal caving in extra-thick coal seams, which integrates continuous block elements and cohesive particle elements to simulate the dynamic mining pressure induced by periodic breaking of overlying strata and the top-coal flow, respectively [23].…”

Section: Introductionmentioning

confidence: 99%

Optimizing Simulation and Analysis of Automated Top-Coal Drawing Technique in Extra-Thick Coal Seams

Yuan

Wang

et al. 2020

Energies

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A particle element approach based on continuum-discontinuum element method (CDEM) is applied to optimize the automated top-coal drawing techniques in extra-thick coal seams. Numerical models with 100 drawing openings are created according to the field engineering geological conditions of Tongxin coal mine in China. An automated coal drawing control approach in numerical modelling based on time criterion is proposed. The rock mixed rate, top-coal recovery rate and the variance of the drawn top coal amount are counted and set as the statistical indicators to evaluate the top-coal drawing techniques. The traditional top-coal drawing criterion, “rocks appear, close the opening”, leads to low recovery of top coal and waste of coal resources in extra-thick coal seams, significantly weakening the transport stability and efficiency of the scraper conveyer. A three-round unequal time top-coal drawing technique is proposed for automated top-coal drawing. Three drawing openings, corresponding to the three top-coal drawing rounds respectively, are working at the same time; in each round, the top-coal drawing sequence is from the first drawing opening at one end of the working face to last drawing opening at another end; the drawing time of each round is not equal and increases with the round number. The numerical inversion approach of iteration steps can be used for real top-coal drawing time estimation and automated drawing process design to achieve a better top coal drawing effect, while the exact time for each drawing round still needs to be corrected by engineering practice.

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Study of automated top-coal caving in extra-thick coal seams using the continuum-discontinuum element method

Cited by 42 publications

References 23 publications

Numerical Damping Calibration Study of Particle Element Method-Based Dynamic Relaxation Approach for Modeling Longwall Top-Coal Caving

Numerical Damping Calibration Study of Particle Element Method-Based Dynamic Relaxation Approach for Modeling Longwall Top-Coal Caving

Using Continuum-Discontinuum Element Method to Model the Foliation-Affected Fracturing in Rock Brazilian Test

Optimizing Simulation and Analysis of Automated Top-Coal Drawing Technique in Extra-Thick Coal Seams

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