煤与瓦斯突出局部防突措施失效判定方法

Failure determination method regarding local outburst prevention measures for coal and gas outburst

  • 摘要: 打排放孔是局部防突的主要措施,但近年来发生过多起打完防突钻孔、采取局部防突措施后仍然发生突出的事故案例。究其原因,在于防突措施未实现其预期目标,处于失效状态。而如何有效判定措施是否起到防突效果是防治事故的关键一环。因此,针对此情形,以突出灾害核心要素中的地应力为着力点,提出了适用于掘进工作面的防治煤与瓦斯突出措施失效判定方法并进行应用效果分析。其主要结论如下:基于工作面应力分布特征推演了局部防突措施的失效判定方法。该方法分为2部分:其一,措施的采取未注意避免对破碎区煤体的破坏,致使其强度降低进而诱发突出;其二,应力集中带内的高应力与高瓦斯并未有效卸放,且打破了原有的动态平衡状态致使灾害的发生。利用应变软化与煤体扩容概念更精确地解算了破碎区、塑性区以及弹性区的应力、应变和宽度范围,并结合失效判定方法的内容确定了它的定量表征形式。以局部防突措施的技术要求为基础,应用失效判定方法确定了《防治煤与瓦斯突出细则》中规定的超前钻孔、松动爆破以及水力疏松措施的钻孔最佳长度。基于失效判据列举出了典型钻孔失效类型,并针对其失效机制进行了定性定量的阐述。该研究成果有助于合理布置与优化掘进工作面防突措施,增强措施防突效果。

     

    Abstract: Discharge holes is the primary measure concerning local outburst prevention, however, in recent years, there have been numerous instances of accidents in which outburst still occurred, after drilling outburst prevention holes and taking local outburst prevention measures. The reason lies in the fact that those measures haven’t realized their expected goals and are in a state of failure. How to determine the effectiveness of measures to prevent accidents is a crucial link. Therefore, in view of this situation, taking the core elements of outburst as the focus point, namely in-situ stress, the failure determination method concerning localized measures preventing coal and gas outburst in excavation working face was proposed and applied. The primary conclusions were as follows: based on the stress distribution characteristics of the working face, a failure determination method regarding local outburst prevention measures was proposed. It was divided into two aspects: firstly, measures taken didn’t pay attention to avoid the destruction of coal in the fracture area, resulting in the reduction of its strength and thus inducing a disaster; secondly, the gas and stress in the stress-concentration area, were ineffectively unloaded, which led to breaking the original equilibrium state and promoting the occurrence of outburst. According to the concept of stress-softening and dilatancy of coal mass, the stresses, strains, and widths in the three areas, namely fracture area, plastic area, and elastic area, in front of the working face were recalculated. Meanwhile, a quantitative form regarding the failure criterion mechanism was defined in relation to its content. According to the technical requirements of local outburst prevention measures, the optimal drilling length for advanced drilling, loose blasting, and hydraulic loosing was regulated by using the failure determination method. Depending on the failure criterion, typical drilling failure types were listed as well as the failure mechanism was qualitatively and quantitatively described. The research can help to reasonably arrange and optimize the localized measures in the excavation face, enhance the effectiveness regarding outburst prevention measures.

     

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