Impact of Connecting Return Airway on the Distribution of"Three Zones"of Spontaneous Combustion in Mined-out Areas
To explore the impact of working contact airway on the distribution of the"three zones"of spontaneous combustion in goaf,taking the 18505 fully mechanized mining face in Xiegou Coal Mine as an example,six different distances between the connecting airway and the working face were selected to construct a physical model.The Fluent numerical simulation method was used to numerically simulate the leakage airflow field in the goaf,and to analyze and study the changes in the leakage airflow field and the distribution law of the"three zones"of spontaneous combustion at different positions of the connecting airway.The results show that with the increase of the distance between the working contact airway and the face,the leakage airflow field in the goaf change from a source-sink to a source-two sinks.The wind speed in the intake airway and the middle section of the face show a non-linear decreasing trend,while the leakage wind speed on the return airway side of the face shows a trend of decreasing and then increasing before decreasing again.The width of the cooling zone on the return airway side of the face increases by about 2.7 times,while the increase in width for the middle section and intake airway side of the face are no more than 75 m.The width of the oxidation and heating zone in the middle section and intake airway side of the goaf show an increasing trend,with the maximum width in the middle section reaching 199 m.The width of the oxidation and heating zone on the return airway side of the goaf show a decreasing trend,with the width decreasing by about 0.5 times.The research findings can provide guidance for the prevention and control of coal spontaneous combustion in similar working faces.
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