综采面覆岩结构稳定控制的推采速度效应

Effect of mining speed on stability control of overburden structure in fully mechanized coal face

开采速度会影响采空区矸石压缩变形,改变基本顶断裂岩块运移位态,影响覆岩结构稳定及矿压显现.采用理论分析和现场实测的方法,建立了考虑矸石压缩效应的"砌体梁"结构模型,分析了推进速度与矸石变形的内在联系,揭示了推进速度对覆岩结构稳定及控制的影响规律.结果表明:随推进速度加快,关键块C下沉量及回转角呈近似负指数关系衰减,进而增加岩块间挤压程度与水平推力,对控制关键块滑落失稳有利;矸石压缩对关键块B触矸后运动影响不大,故分析回转失稳时应回归B块断裂回转至触矸的过程.回转失稳主要与采空区充填程度有关.因提速增加的岩块间水平推力有助于补偿滑落失稳产生的附加载荷,减小支架受力,一旦结构实现自稳,所需支架工作阻力将趋于恒定.

Mining speed affects the compressive deformation of caving gangue in goaf,and changes the movement of the fractured block of the main roof,and influences the overburden structure stability and the ground pressure behavior.By means of theoretical analysis and field measurement,the"voussoir beam"model considering the effect of gangue compressive deformation was developed.The relations between mining speed and gangue compressive deformation were analyzed.After that,the influence of mining speed on the stability and control of overburden structure were revealed.The results show that with the increase of mining speed,the subsidence value and rotating angle of key block C decrease by an approximately negative exponential relationship.This increases the extrusion degree and horizontal thrust between rocks,which is beneficial to control the sliding instability of key block.However,gangue compression has little influence on the movement of the key block B after it contacts gangue.The rotating instability analysis should return to the process of block B breaking and turning to gangue.The rotating instability is mainly related to the degree of goaf filling.The increased horizontal thrust caused by the increase of mining speed,which is helpful to compensate the additional load caused by sliding instability and reduce the supporting force.Once the structure is self-stabilized,the required working resistance of support tends to be constant.