Longwall Mining

Peng, Syd S.

doi:10.1201/9780429260049

Cited by 78 publications

(99 citation statements)

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“…If Δ=0, that is, the collapsed materials fill the whole goaf and support the load of the overlying rock strata (Whittles et al 2006, Peng 2006, then:…”

Section: Roof Presplitting Heightmentioning

confidence: 99%

Investigation of the Roof Presplitting and Rock Mass Filling Approach on Controlling Large Deformations and Coal Bumps in Deep High-Stress Roadways

2019

Lat. Am. j. solids struct.

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Roadway deformation and coal bumps are major challenges for underground engineering. Taking the Lu'an mining district in Shanxi Province as an example, the failure mechanism of deep high-stress roadway was studied. Numerical simulations and the similar material test were performed to investigate the effect of the roof presplitting and rock mass filling on the stability of roadway surrounding rock. The change laws and distribution features of stress and plastic zone, and the fracture characteristics of roof strata were analyzed. Under conditions where the roof was not presplit, the roadway was in a high-stress environment due to the massive suspended roof. The failure process of the high-stress roadway began with tensile crack in the shallow roof and then extended to the two ribs, resulting in the yield of a coal pillar. Under the condition that the roof was presplit, the peak value of the vertical stress at the coal pillar was decreased from 18.2 to 9.8 MPa while that of the virgin coal rib was decreased from 15.8 to 13.5 MPa. Both the similar material test and numerical results showed that the Roof outside the Coal Pillar (RCP) was cut off along the presplitting lines and was fractured into different sizes of masses. The broken rock mass filled in the goaf and supported on the overlying strata, which reduced the load on the coal pillar. The field monitoring data indicated that implementing the roof presplitting and rock mass filling processes successfully controlled large deformations of the roadway and coal bumps, which improved the stability of surrounding rock.

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“…If Δ=0, that is, the collapsed materials fill the whole goaf and support the load of the overlying rock strata (Whittles et al 2006, Peng 2006, then:…”

Section: Roof Presplitting Heightmentioning

confidence: 99%

Investigation of the Roof Presplitting and Rock Mass Filling Approach on Controlling Large Deformations and Coal Bumps in Deep High-Stress Roadways

2019

Lat. Am. j. solids struct.

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“…The two variables selected in this study are the lengths of the leg and the equilibrium jack (can be obtained using pull on the rope displacement sensors). The loopclosure condition of the vectors JABEI and EFG can be written as: 3 9…”

Section: Pose Monitoring Model Of the Supportmentioning

confidence: 99%

“…Longwall mining has gradually become the most predominant mining method worldwide for the underground extraction of coal seams since its introduction in America in the 1950s [1,2]. The basic equipment of longwall method includes a shearer to cut the coal seam, an armoured face conveyor (AFC) to transport the coal, and a series of hydraulic supports to prevent excessive roof-tofloor convergence and to provide a safe environment for all the above activities [3,4]. To this end, hydraulic supports must be advanced with minimum delay and rise quickly to reduce the exposure time of the roof [5,6].…”

Section: Introductionmentioning

confidence: 99%

Pose Adjusting Simulation of Hydraulic Support Based on Mechanical-Electrical-Hydraulic Coordination

et al. 2018

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The pose variations of the hydraulic support have significant influence on its performance. And the pose adjusting operations are required to be fast and precise, while they have typical mechanical-electric-hydraulic coordination characteristics which are challenging to simulate. In view of these problems, a method has been proposed in this work for accurately monitoring and controlling the pose of the hydraulic support, and using a suitable multi-software co-simulation model to simulate it. A mathematical model for pose monitoring and control was initially established.A teaching-learning-based optimization algorithm (TLBO) was then introduced to obtain the numerical solution of the nonlinear equations.Finally, a numerical model based on mechanical-electrical-hydraulic co-simulation was established. The model was tested and validated by using different pose signals. The results indicate that the pose controller developed in this paper can control the support pose well (iteration time less than 1 s and cumulative error less than 1.5 mm). Moreover, the multi-software co-simulation approach was effective for describing the complex system. The co-simulation platform proposed in this study can benefit the virtual monitoring technology for hydraulic supports.The research provides theoretical basis and technical guidance for the automation and unmanned control of underground mining.

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“…Longwall mining methods, which became popular in the 1970s, use mechanical roof supports adjacent to the working face. Subsidence and collapse of roof materials into the mine immediately follows advance of the face and roof supports (Peng and Chiang, 1984).…”

Section: Coal Miningmentioning

confidence: 99%

Flooding and reequilibration of a series of Pittsburgh bed underground coal mines, 1980 to 2015

Light¹

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This study examines the water-level elevation history of selected flooding and flooded underground mines in the Pittsburgh coal basin of SW Pennsylvania from the time of closure until post-flooding pool-level reequilibration. Mines within this mining district developed pools with nearly steady-state groundwater flow within 10 to 50 years after closure. Equilibrated pool levels within each of the mines were controlled by various combinations of spillage to the surface or other mines, pumpage, and barrier leakage. In a study of flooding in the Clarksville, PA area, field water-level observations, mine geometry, barrier hydraulic conductivity, recharge rates, and late-stage storage gains were parameterized to match known pumping rates and develop a fluid mass balance. Vertical infiltration (recharge and leakage) estimates were developed using a depth-dependent model based on the assumption that most vertical infiltration is focused in areas with <75 m of overburden. A MODFLOW simulation of the nearly steadystate flow conditions was calibrated to hydraulic heads in observation wells and to known pumping rates by varying barrier hydraulic conductivity. The calibrated model suggests significant head-driven leakage between adjacent mines, both horizontally through coal barriers and vertically through interburden into an overlying mine. Calibrated barrier hydraulic conductivities were significantly greater than literature values for other mines at similar depths in the region. This suggests that some barriers may be hydraulically compromised by un-mapped entries, horizontal boreholes, or similar features that act to interconnect mines. These model results suggest that post-mining inter-annual equilibrium conditions are amenable to quantitative description using mine maps, sparse observation-well data, accurately-estimated pumping rates, and depth-dependent vertical infiltration estimates. Results are applicable to planning for postflooding water control schemes, although hydraulic testing may be required to verify model results. iv ACKNOWLEDGEMENTS I would like to express my gratitude to Dr. Joe Donovan whose enduring patience and encouragement allowed me to complete this manuscript. Eberhard Werner and the late Bruce Leavitt provided insight into various aspects of mining and mine hydrology. Information regarding mine operations was provided by Joe Lapkowicz, former mining engineer in Gateway mine. Ken Dufalla, President of the Izaak Walton League of Greene County, shared observations on the location and timing of surface discharges from Clyde and Pitt Gas mines. T. D. Light, J. Hawkins, and two anonymous reviewers provided comments that improved Chapter 3 v

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Longwall Mining

Cited by 78 publications

References 0 publications

Investigation of the Roof Presplitting and Rock Mass Filling Approach on Controlling Large Deformations and Coal Bumps in Deep High-Stress Roadways

Investigation of the Roof Presplitting and Rock Mass Filling Approach on Controlling Large Deformations and Coal Bumps in Deep High-Stress Roadways

Pose Adjusting Simulation of Hydraulic Support Based on Mechanical-Electrical-Hydraulic Coordination

Flooding and reequilibration of a series of Pittsburgh bed underground coal mines, 1980 to 2015

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