王恩元,李德行,刘晓斐,等. 受载煤体微电流效应及煤岩动力灾害预警应用展望[J]. 煤炭学报,2024,49(2):695−706. DOI: 10.13225/j.cnki.jccs.ST23.1688
引用本文: 王恩元,李德行,刘晓斐,等. 受载煤体微电流效应及煤岩动力灾害预警应用展望[J]. 煤炭学报,2024,49(2):695−706. DOI: 10.13225/j.cnki.jccs.ST23.1688
WANG Enyuan,LI Dexing,LIU Xiaofei,et al. Weak current phenomenon in stressed coal and its prospective applications in early warning for coal and rock dynamic disasters[J]. Journal of China Coal Society,2024,49(2):695−706. DOI: 10.13225/j.cnki.jccs.ST23.1688
Citation: WANG Enyuan,LI Dexing,LIU Xiaofei,et al. Weak current phenomenon in stressed coal and its prospective applications in early warning for coal and rock dynamic disasters[J]. Journal of China Coal Society,2024,49(2):695−706. DOI: 10.13225/j.cnki.jccs.ST23.1688

受载煤体微电流效应及煤岩动力灾害预警应用展望

Weak current phenomenon in stressed coal and its prospective applications in early warning for coal and rock dynamic disasters

  • 摘要: 利用建立的受载煤体微电流测试系统,开展不同加载条件下煤样微电流测试试验,研究揭示煤体受载变形微电流效应,分析煤体受载变形过程微电流响应特征,研究微电流与煤体力学行为间的定量关系,提出微电流法预测煤岩动力灾害的原理,结合现场实践结果,对微电流技术的应用前景进行展望。结果表明,煤体受载变形能够产生微电流,微电流变化与应力变化具有较好的一致性,微电流与煤体力学行为(应力、应变、应变率等)紧密相关,在压密阶段和塑性变形阶段,微电流随应变率增加而增加,在弹性变形阶段随应力和应变线性增加;煤体在扰动载荷下能够产生随应力周期性变化的微电流,即脉动直流电,其变化与应力变化一致。微电流对煤体破坏具有较好的前兆响应,微电流在加速增加过程(塑性变形阶段)中的异常波动可作为煤体渐进性破坏的前兆特征,微电流在衰减过程中的脉冲式波动可作为煤体蠕变破坏的前兆特征。煤体受载微电流效应及现场应力梯度的存在,是矿井微电流测试的重要基础;微电流与煤体力学行为间的紧密相关性,是利用微电流技术观测煤岩体应力的重要前提;微电流对煤体破坏具有明显的前兆响应,是利用微电流技术预测预报煤岩动力灾害的重要保障。微电流技术具有响应灵敏度高、前兆信息明显和抗干扰能力强的优点,在煤岩体应力观测及煤岩动力灾害预警中具有很好的应用前景。未来需进一步开展受载煤岩微电流基础理论及应用技术方面的研究,为发展煤岩动力灾害精准时空监测预警的微电流法提供支撑。

     

    Abstract: In this study, some loading experiments were conducted on coal specimens using the established weak current testing system to investigate the effects of weak currents in coals. The response characteristics of weak currents during the coal deformation process were analyzed, and a quantitative relationship between weak currents and the mechanical behaviors of coal was established. The principles for predicting coal and rock dynamic disasters based on the weak current method were proposed. Furthermore, drawing upon the results obtained from on-site practical applications, a forward-looking assessment of the potential applications of this methodology is presented. The results indicate that the deformation of loaded coal generates weak currents. The fluctuations in these weak currents exhibit a notable alignment with variations in stress, with the magnitude closely tied to the coal mechanical characteristics like stress, strain, and strain rate. Notably, in the compaction and plastic deformation stages, the weak current rises in tandem with the strain rate, while in the elastic deformation stage, the weak current exhibits a linear increase in correlation with stress and strain. Under perturbation loading, the coal produces some periodic weak currents, referred to as the pulsating direct current (PDC). And the variations in the PDC align with stress changes. Furthermore, the weak current demonstrates a reliable precursor response to coal damage, with some unusual fluctuations observed during the accelerated increase process (plastic deformation stage) serving as the precursor indicators for the progressive failure of coal. Conversely, the pulse-like fluctuations observed during the attenuation process can be regarded as the precursor features for the coal's creep failure. The phenomenon of weak currents in stressed coal serves as a pivotal foundation for conducting weak current measurements in mines. The intimate correlation between weak currents and the mechanical behaviors of coal underscores a crucial prerequisite for employing the weak current technology in monitoring stress within coal and rock formations. Furthermore, the discernible precursor response of weak currents to coal damage provides a vital assurance for predicting coal and rock dynamic disasters through the utilization of weak current technology. The weak current technology possesses some advantages such as high responsiveness, clear precursor signals, and robust anti-interference capabilities. These attributes make it highly promising for some applications in the stress monitoring within coal/rock mass and the early warning for coal and rock dynamic disasters. In the future, some further researches on the fundamental theory and applied technology of weak current in stressed coal and rock are needed to provide a support for the development of precise spatiotemporal monitoring and early warning of coal rock dynamic disasters using the weak current methods.

     

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