浅埋煤层开采顶板切落条件下支架动载效应

摘要

针对浅埋煤层开采周期来压过程中顶板沿煤壁切落时对支架造成冲击的现象,根据基本顸回转切落造成直接顶岩体非线性破坏特征,建立了由基本顶-直接顶-支架-采空区矸石组成的力学模型,应用突变理论和岩石动力学方法,推导了直接顶失稳前后基本顶切落荷载作用下的支架压缩量表达式,分析了顶板切落过程中的动载效应,获得了顶板切落条件下支架工作阻力.研究结果表明:基本顶回转切落和直接顶失稳破坏是造成支架冲击的主因,直接顶岩体变形的突变量决定了冲击荷载的大小,系统失稳时的支架荷载除了与基本顶的周期来压步距、上覆岩层荷载、直接顶厚度有关外,还与支架和直接顶岩体的刚度比、直接顶岩体性质等因素相关.%Based on the dynamic effect of support while roof cutting during the periodic weighting in shallow seam mining,a system mechanical model composed by upper roof,immediate roof,powered support and waste rock was established in this study.The compression quantities of the support under dynamic loading after the system instability was obtained by using catastrophic theory and rock dynamics.The support dynamic loading effect was analyzed while roof cutting,and the working resistance of support was determined.The results showed that the support capacity was related to the cycle weighting interval,the upper load and the thickness of immediate roof,also related to the stiffness ratio of immediate roof and support and the material parameters when the system was unstable.The rotation and cutting of upper roof and the unstable failure of immediate roof are main reasons for the support impact.The rationality of theoretical derivation was verified by the coal mine.