松软破碎厚顶煤大跨度切眼变形破坏特征与控制技术

Deformation and failure characteristics and control technology of large-span open-off cut in soft and broken thick top coal

安阳主焦煤矿大断面切眼常采用被动支架沿顶布置,围岩变形量大、易漏冒,工人劳动强度大。针对上述问题,采用数值模拟方法研究了裂隙发育、位移和应力分布与切眼跨度之间的关系,提出了围岩控制策略和支护方案。结果表明,随着切眼跨度的增大,围岩塑性区范围逐渐增加,顶板以剪切滑移或拉剪破坏为主,两帮以泊松效应膨胀拉伸—剪切破坏为主;顶板下沉量、巷帮内挤和底鼓量均逐渐增大;顶煤、直接顶和基本顶部分岩层逐层渐次移动,顶板部分区域出现较大的裂隙,冒落拱以上深部顶板发生整体移动;巷道顶底板中有害拉伸应力区域范围呈现拱形分布,且逐渐增大。根据切眼围岩变形破坏特征,提出了高强度、高刚度、高预紧力的强力支护和被动单体液压支柱补强的主被动联合支护方法。现场工业性试验表明,切眼围岩得到了有效控制,可为类似裂隙发育托顶煤大断面切眼围岩控制提供参考。

The large cross-section open-off cut of Anyang Zhujiao Coal Mine often uses passive supports arranged along the roof,resulting in large deformation of surrounding rock,easy leakage,and high labor intensity for workers.In response to the above issues,numerical simulation methods were used to study the relationship between crack development,displacement and stress distribution,and the span of the open-off cut.Surrounding rock control strategy and support plan were proposed.The results showed that as the span of the open-off cut increased,the range of the plastic zone in the surrounding rock gradually increased.The roof was mainly subjected to shear slip or tensile shear failure,while the two sides were mainly subjected to Poisson effect expansion tensile and shear failure.The subsidence of the roof,the inward squeezing of the roadway,and the floor heave gradually increased.The top coal,direct roof,and main roof strata gradually moved layer by layer,with large cracks appearing in some areas of the roof,and overall movement of the deep roof above the falling arch.The range of harmful tensile stress areas in the roof and floor of the roadway presented an arched distribution and gradually increases.Based on the deformation and failure characteristics of the surrounding rock of the open-off cut,a combined active and passive supporting method of high-strength,high stiffness,and high preload strong supporting coupling passive single hydraulic prop reinforcement was proposed.Field investigations have shown that the surrounding rock of the open-off cut has been effectively controlled,providing reference for the control of large cross-section open-off cut surrounding rock similar to the development of fissures in supporting top coal.