• 论文
主办单位:煤炭科学研究总院有限公司、中国煤炭学会学术期刊工作委员会
真三轴加载条件下含瓦斯煤体复合动力灾害及钻孔卸压试验研究
  • Title

    Experimental study on compound dynamic disaster and drilling pressure relief of gas-bearing coal under true triaxial loading

  • 作者

    鲁俊尹光志高恒李铭辉邓博知

  • Author

    LU Jun1,2 ,YIN Guangzhi1,2 ,GAO Heng1,2 ,LI Minghui1,2 ,DENG Bozhi1,2

  • 单位

    重庆大学 煤矿灾害动力学与控制国家重点实验室重庆大学 资源及环境科学学院

  • Organization
    1. State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing  400030,China; 2. College of Resources and Environ-mental Sciences,Chongqing University,Chongqing  400030,China
  • 摘要

    煤与瓦斯突出、冲击地压等动力灾害严重威胁矿山安全高效生产。煤矿进入深部开采后,受原岩应力升高及地质赋存条件变化的影响,冲击与突出复合型动力灾害呈逐渐增多趋势,其发生原因、机理较单一动力灾害更为复杂。因此研究深部煤矿复合动力灾害致灾机理对于动力灾害的有效防治至关重要。

    本文基于自主研制的“多功能真三轴流固耦合试验系统”,进行了考虑气体影响的完整煤样和卸压孔煤样的5面加载、单面临空试验。

    结果表明,复合动力灾害是煤岩在应变能和气体内能作用下非线性瞬发性破坏的动态过程。其发生过程具有明显的阶段性,主要经历颗粒弹射、碎片弹射、局部煤体破坏、煤体抛出失稳和重新平衡状态,煤样破坏后形成明显弧形阶梯状煤体抛出坑。中间主应力在一定范围内有增强煤样强度的特性,试样强度随中间主应力的增加而逐渐增加,试样破坏后形成平行于中间主应力方向的主断裂面。

    钻孔卸压措施可在一定程度上改善煤岩力学性质,软化煤岩结构,降低煤岩强度,增强其塑性变形特性,使集聚的弹性能量缓慢释放,降低动力灾害发生的可能性。

    对比试验结果表明,卸压孔平行于中间主应力时煤样产生的塑性区范围更大,塑性程度更强,钻孔后的试样破坏后形成明显的阶梯式层裂结构,与未钻孔和其他钻孔布置方式相比,致灾程度弱化,无明显动力显现特征,卸压效果更好。

           卸压钻孔主要通过优化能量释放结构,促进煤岩渐进式损伤,最终煤岩趋于静态缓慢式破坏。针对现场具体工程条件,提出了根据实际地应力、地质条件等布置卸压钻孔方位的技术方案和可行的治理措施。

  • Abstract

    Coal and gas outburst,impact ground pressure and other dynamic disasters seriously threaten the safe and efficient production of coal mines. After the coal mine enters deep mining stage,the impact and outburst compound dy- namic disasters are gradually increasing due to the increase of original rock stress and the change of geological conditions. The causes and mechanisms are more complicated than that of single dynamic disaster. Therefore,studying the mechanism of compound dynamic disasters in deep coal mines is crucial for the effective prevention and control of dy- namic disasters. Based on the self-developed “multi-functional true triaxial fluid-solid coupling test system”,the tests were carried out on the intact coal sample and the coal sample with pressure relief borehole considering the influence of gas under the condition of five faces loading and one face free. Results show that the compound disaster is a dynamic process of nonlinear transient damage of coal and rock under the action of strain energy and gas internal energy. The occurrence process has obvious stages,mainly undergoing particle ejection,fragment ejection,local coal body damage, overall instability after coal body throwing, and rebalancing state. The intermediate principal stress enhances the strength of coal sample within a certain range,the strength of the sample gradually increases with the increase of inter- mediate principal stress,and the main fracture surface parallel to the intermediate principal stress after the sample is destroyed. Drilling pressure relief measures can change the mechanical properties of coal rock,soften the structure,re- duce the strength,and enhance its plastic deformation characteristics,which cause the elastic energy released slowly reducing the possibility of the dynamic disaster. The comparison test results show that the plastic zone of the coal sam- ple is larger and the plasticity degree is stronger when the pressure relief hole is parallel to the intermediate principal stress. After the sample containing the pressure relief borehole is broken, a distinct stepped spallation structure is formed. Compared with the un-drilled and other drilling orientations,the degree of disaster is weakened,there is no ob- vious dynamic display characteristics,and the pressure relief effect is better. The pressure relief borehole leads to the static slow failure of the coal rock by optimizing the energy release structure and promoting the progressive slow dam- age. According to the specific engineering conditions,the technical solutions and feasible control measures were pro- posed for the relief drilling borehole according to the actual in-situ stress and geological conditions.

  • 关键词

    真三轴应力复合动力灾害强度钻孔卸压含瓦斯煤体

  • KeyWords

    true triaxial stress condition;compound dynamic disaster;strength;crack;drilling pressure relief;gas-bear- ing coal

  • 基金项目(Foundation)
    国家自然科学基金资助项目(51874053,51434003,51374256)
  • DOI
  • Citation
    LU Jun,YIN Guangzhi,GAO Heng,et al. Experimental study on compound dynamic disaster and drilling pressure relief of gas-bearing coal under true triaxial loading[J]. Journal of China Coal Society,2020,45(5):1812 -1823.
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