Bai Jinwen, Feng Guorui, Wang Shanyong, Qi Tingye, Yang Jian, Guo Jun, Li Zhen, Du Xianjie, Wang Zehua, Du Yunlou, Zhang Yujiang
College of Mining Technology, Taiyuan University of Technology, Taiyuan, Shanxi 030024, People's Republic of China.
Research Center of Green Mining Engineering Technology in Shanxi Province, Taiyuan, Shanxi 030024, People's Republic of China.
R Soc Open Sci. 2018 Aug 8;5(8):180346. doi: 10.1098/rsos.180346. eCollection 2018 Aug.
Upward mining of the residual coal seam over an abandoned pillar working is one of the effective measures to alleviate the contradiction between limited resources and increased consumption. Interburden stability over an abandoned pillar working plays a significant role in guaranteeing the safety of upward mining; however, it has not yet been extensively studied and understood. In this study, the vertical stress of the interburden over an abandoned pillar working was first investigated. The mechanical model of the interburden was established and the damage conditions were analysed. Then, the stability of the interburden over 38502 abandoned workings in Baijiazhuang coal mine was determined by mechanical analysis and field monitoring. The results show that: (i) Vertical stress of the interburden over abandoned mining zones is clearly lower than the initial stress, indicating the existence of a de-stressed effect. Moreover, vertical stress of the interburden over residual coal pillars is greater than the initial stress, which is the evidence of a stress concentration effect. (ii) The interburden over an abandoned pillar working should be regarded as an elastic rectangular plate supported by generalized Kelvin bodies in mechanical modelling. (iii) The interburden over abandoned mining zones may experience two damage stages. In the first stage, initial plastic damage appears at the central region of interburden. In the second stage, the plastic damage evolves from the central point to the surrounding areas. (iv) The mechanical analysis and field monitoring both indicate the initial damage occurred at the central region over 38502 abandoned workings in Baijiazhuang coal mine before upward mining. Related rock control measures should be implemented in that region to guarantee the safe mining of the residual coal seam.
在废弃煤柱上方进行残留煤层的上行开采是缓解资源有限与消耗增加之间矛盾的有效措施之一。废弃煤柱上方覆岩的稳定性对保证上行开采的安全起着重要作用；然而，目前对此尚未进行广泛的研究和了解。在本研究中，首先对废弃煤柱上方覆岩的垂直应力进行了研究。建立了覆岩的力学模型并分析了其破坏情况。然后，通过力学分析和现场监测确定了白家沟煤矿38502废弃采空区上方覆岩的稳定性。结果表明：(i) 废弃采空区上方覆岩的垂直应力明显低于初始应力，表明存在应力释放效应。此外，残留煤柱上方覆岩的垂直应力大于初始应力，这是应力集中效应的证据。(ii) 在力学建模中，废弃煤柱上方的覆岩应视为由广义开尔文体支撑的弹性矩形板。(iii) 废弃采空区上方的覆岩可能经历两个破坏阶段。第一阶段，覆岩中部区域出现初始塑性破坏。第二阶段，塑性破坏从中心点向周边区域发展。(iv) 力学分析和现场监测均表明，白家沟煤矿38502废弃采空区上方在进行上行开采前，中部区域已发生初始破坏。应在该区域实施相关的围岩控制措施，以保证残留煤层的安全开采。
