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为研究煤矿中岩芯饼化现象的产生机理,结合开滦矿区赵各庄矿地应力测量过程中的岩芯饼化现象,构建了力学模型;基于拉应力条件和能量理论分别给出了煤矿中饼化现象产生的判据,并结合地应力实测结果,采用理论计算和数值模拟方法对饼化判据进行了验证。研究结果表明:利用空心包体地应力测定方法测定地应力时,岩芯顶部所受摩擦力逐渐减小,在被应力解除的岩芯根部合成出一个指向顶部方向逐渐增大的拉应力,当该拉应力大于岩芯本身抗拉强度时,会出现饼化现象,随着套筒的继续解除,此过程将重复地发生下去;从能量角度来判断,赵各庄矿岩芯饼化现象属于岩芯积聚弹性能的周期性释放,当岩芯集聚的弹性能大于生成饼化岩芯所需能量时,即具备了饼化发生的能量条件,其发生次数由弹性余能来控制,表现为套筒平均每钻进22.1 mm,岩芯将生成一段岩饼。理论验证结果表明,力学模型中岩芯集聚的弹性能足以支持饼化现象发生24次,饼化岩芯的平均厚度为20.8 mm,与实际观测结果基本相符;模拟验证结果表明,套筒每钻进20 mm时,在被应力解除的岩芯根部形成饼状破裂,破裂过程随着套筒的持续钻进而重复发生。
In order to study the mechanism of core cake formation in coal mines, a mechanical model was constructed based on the phenomenon of rock cake during the stress measurement of Zhaoguanzhuang Mine in Kailuan Mine. Based on the tensile stress conditions and energy theory, In the paper, the criteria of cake formation are combined with the results of in-situ stress measurement. The criterion of cake formation is verified by theoretical calculation and numerical simulation. The results show that the friction force at the top of the core decreases with the determination of the stress of the hollow inclusions, and a tensile stress increases gradually toward the top of the core that is relieved by stress. The tensile stress is greater than the tensile strength of the core itself when piecing occurs, with the sleeve continued to lift, the process will continue to happen; judging from the energy point of view, Zhao Gezhuang core cake phenomenon belongs to The cyclical release of core accumulation elastic properties, when the elastic core aggregation is greater than the energy required to generate caked core, that is, with the occurrence of the energy conditions of the pie, the occurrence of the number of times by the elastic residual energy to control, expressed as An average of 22.1 mm of casing per drill, the core will generate a rock cake. The theoretical verification results show that the elasticity of the core accumulation in the mechanical model is sufficient to support the occurrence of caking for 24 times and the average thickness of the caked core is 20.8 mm, which is in good agreement with the actual observation results. The simulation results show that, When entering 20 mm, a cake-like rupture is formed at the core of the stress-relieved core. The rupture process repeats as the sleeve continues to drill.