综放沿空巷道非对称变形破坏主控因素与支-卸协同控制

Support-pressure relief coordination control and asymmetric deformation and failure key control factors of gob-side entry in fully mechanized caving face

针对厚煤层综放开采沿空巷道所面临煤柱合理留设、掘采多重扰动、断面大、托软弱厚顶煤等问题,采用现场调研、理论研究与工程实践相结合的方法,分析综放沿空掘巷围岩非对称变形破坏特征,揭示其本质原因与主控因素,提出大断面综放沿空巷道围岩控制要求及支护-卸压协同控制技术体系。研究结果表明:覆岩结构和应力在巷道断面垂直和水平方向呈明显非对称分布是综放沿空巷道围岩非对称变形破坏的本质原因;掘、采多重扰动,覆岩关键岩块活动,托软弱厚顶煤,存在围岩薄弱体-煤柱,截面尺寸大,围岩控制技术不科学等问题,是引发覆岩结构与应力非对称分布的主控因素;综放沿空巷道围岩控制技术应满足适应顶板非对称变形特征,具有较强的抗剪切能力,提高煤柱承载能力,人工干预覆岩结构特征、改善应力环境等要求;在整个服务期间,受掘、采扰动,围岩变形主要表现为两帮收敛量较大,顶底板移近相对较小;水力压裂卸压技术通过改变顶板覆岩结构,降低和转移高水平应力,可明显降低巷道围岩应力及工作面来压强度;近场高预应力强力差异化支护-远场水力压裂卸压协同控制技术体系能够适应大断面综放沿空小煤柱掘巷围岩非对称变形破坏特性,全面抑制巷道围岩失稳。

Aiming at the problems of reasonable coal pillar retention,multiple disturbances in mining,large cross section,and weak thick top coal in full-mechanized caving mining along the gob of thick coal seam,using the method of combining field investigation,theoretical research and engineering practice,the asymmetric deformation and failure characteristics of the surrounding rock in the fully mechanized gob-side roadway are analyzed,the essential reasons and main controlling factors are revealed,and the surrounding rock control requirements of gob side entry in large section fully mechanized top coal caving face and the support pressure relief cooperative control technology system are put forward.Investigation results show that the obvious asymmetric distribution of overburden structure and stress in vertical and horizontal direction of roadway section is the essential reason for surrounding rock asymmetric deformation and failure of gob-side entry in fully mechanized top coal caving workface.Multiple disturbance of excavation and mining,key block rotary motion,soft and thick top coal,existence of weak body in surrounding rock,large cross section size of roadway,unreasonable support are key control factors causing asymmetric distribution of overburden structure and stress.Control technology for surrounding rock of gob-side entry in fully mechanized top coal caving workface should meet the requirements of adapting to the asymmetric deformation characteristics of roof,having strong shear resistance,improving the bearing capacity of coal pillar,manually intervening the structural characteristics of overburden and improving the stress environment.During the whole service period,influenced by excavation and mining disturbance,roadway deformation mainly is appeared that large sidewall convergence,while roof subsidence and floor heave are small.The hydraulic fracturing pressure relief technology could significantly reduce or transfer surrounding rock high-level stress,reduce weighting strength of working face by changing the roof overburden structure.The coordination control technique of high pretension,intensive and differentiation support in near field coupled with hydraulic fracturing pressure relief in far field could adapt to the surrounding rock asymmetric deformation characteristics and control the deformation and failure in gob-side entry with small coal pillar and large cross-section in fully mechanized top coal caving workface.