Abstract
The shield-roof interaction as mining proceeds in longwall panels remains unclear, hindering the further increase of longwall productivity. To uncover the mechanisms of shield-roof interaction, using our self-developed Status of Shield and Roof IntelliSense (SSRI) system, we investigated the effects of idle time, retreating rate, setting pressure, yielding, and shearer’s cutting, as well as neighboring shields’ advance on the spatial-temporal evolution of leg pressure and leg closure of shields. Our results show that the shield-roof interaction is not only dependent on the shield capacity, but also collectively determined by the time-related factors, the geological condition, the setting pressure, yielding characteristics, and mining method. Understanding the shield-roof interaction in longwall panels enables us to apply the SSRI system for ground control in longwall coal mines. Early warning of severe roof weighting can be achieved by establishing a warning model based on the decision tree algorithm. Apart from this, we can also assess the working condition of yield valve and diagnose fluid leakage of shield cylinder using the SSRI system. Finally, we propose the research prospects on shield-roof interaction in longwall panels to achieve a more reasonable determination of shield capacity, prediction of roof fall and coal wall spalling, and self-adaptive control of the shield.
Highlights
Longwall mining is currently the predominant coal mining method in China, thanks to its high efficiency of coal production [1, 2]. e recent advances in large-cuttingheight mining has launched a new era of longwall coal mining [3]
The retreating process only lasts for tens of minutes to several hours, while the idle time occupies longer time due to various reasons such as regular
We developed a powerful software package Status of Shield and Roof IntelliSense (SSRI), to analyze tons of monitoring data on leg pressure and leg closure of shields in 1.6 million supporting cycles in 11 longwall panels of coal mines in China and the U.S
Summary
Longwall mining is currently the predominant coal mining method in China, thanks to its high efficiency of coal production [1, 2]. e recent advances in large-cuttingheight mining has launched a new era of longwall coal mining [3]. Shangwan mine located in Inner Mongolia started the coal production in the Panel LW 12401 using a record-breaking large-mining-height of 8.8 m on 19 March 2018. Large-cutting-height mining requires strong shield to support the extraordinarily high roof loading, and the shield capacity in this panel reaches 26,000 kN by increasing the diameter of shield leg. A strong shield does not necessarily address all the issues in the longwall panel with large-cutting-height. It is reported that the roof between the front tip of the shield canopy and the coal face falls occasionally [3, 5]. E unwanted idle time caused by roof falls and shield malfunctions hinders the additional growth of longwall productivity. It is reported that the roof between the front tip of the shield canopy and the coal face falls occasionally [3, 5]. e unwanted idle time caused by roof falls and shield malfunctions hinders the additional growth of longwall productivity. e occurrence of these problems indicates our limited understanding on the shield-roof interaction
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