切顶卸压无煤柱自成巷顶板变形机制及控制对策研究

为了探究切顶卸压无煤柱自成巷开采技术下短臂梁顶板的变形机制和影响因素,分析了该技术条件下的顶板结构及运动过程,建立了短臂梁顶板的力学模型,运用功能原理推导了短臂梁顶板在前期、中期和后期3个阶段的变形量计算公式,讨论了短臂梁顶板在各变形阶段的影响因素及其敏感性,并针对各变形阶段的主控因素提出了相应的控制思路。结果表明:短臂梁顶板在前期阶段的变形量较小,此阶段基本顶弹性模量、巷内及切顶支护强度、切顶高度对其影响比较显著;在中期阶段的变形量较大,碎胀系数、短臂梁弹性模量、留巷宽度对其影响比较显著;后期阶段顶板处于相对稳定状态,变形量基本不再变化。为此针对柠条塔矿S12012工作面提出了"巷内及时高强支护+切顶方案优化"的阶段性主控因素控制对策,现场应用效果良好。

Roof deformation mechanism and control measures of pillarless mining with gob-side entry retaining by roof cutting and pressure relief

In order to explore the deformation mechanism and influencing factors of the short cantilever beam under the technology of pillarless mining with gob-side entry retaining by roof cutting and pressure relief,the roof structure and motion process are analyzed,and the mechanical model of the short cantilever beam roof is established.Based on the principle of function,a calculation formula for the deformation of the short cantilever beam roof in the three stages of the early,middle and late stages is derived.The influencing factors and sensitivity of the short cantilever beam roof in each deformation stage are discussed,and the corresponding control ideas are put forward according to the main control factors in each deformation stage.The results show that the deformation of the short cantilever beam roof in the early stage is small.At this stage,the elastic modulus of basic roof,the strength of support in roadway and roof,and the height of short cantilever beam have a significant influence on it.In the medium-term stage,the deformation is large,and is significantly affected by the bulking coefficient,the modulus of the short cantilever beam roof and the width of the roadway.The roof is in a relatively stable state at the later stage,and the deformation is basically no longer changed.A countermeasure of phased main control factors,namely timely high-strength support in roadway+roof cutting plan optimization was proposed for the S12012 working face of Ningtiaota coal mine.Good effect of field application was verified.