采空区上覆火成岩断裂致灾机理研究

On the fracturing mechanism of the igneous rock overlying the goaf

为了解释采空区影响下火成岩断裂破坏诱发地表裂缝的形成原因,通过建立两种采动影响下的火成岩断裂物理力学模型,推导出采动影响下火成岩初次断裂和周期性断裂判据。结合铁法晓南矿开采出现的地表裂缝,分析了火成岩断裂破坏机理,并对火成岩断裂破坏进行了预测。通过与现场实测地表裂缝位置加以验证,证明了所建力学模型的可靠性,并给出了后续生产中关于地表裂缝的规避性建议。

The objective of this paper is to explore the likely factors accounting for the surface fracture induced by the igneous rock failure of the goaf in hoping to disclose the fracture mechanism of such rocks overlying the mining area and provide the needed technological supports.It is for the said purpose that we have established models of properly supported beams and cantilever beams to infer the mechanism lying behind the initial fracture and the cyclical fracture of igneous rock.And,then,we have worked out the distribution regularity of the internal strain and stress in case of the lingering igneous rocks via calculating the safety hanging length of the igneous rock in different distributive positions between the igneous rocks and the goaf.Take the surface crack that is taking place in NO.2 west mining area of Tie Fa Xiao Nan mine for example,we have worked out the scope affected by the goaf with the possibility integral method.The results of our exploration show that the igneous rock has been hollowed partially under the impact of the goaf,which has been proved in accord with the preconditions of the calculation model.Furthermore,we have also worked out the distance of the initial fracture and the cyclical fracture in the igneous rock with the aforementioned theories and methods.The results of our investigation and calculation show that the distance of the initial fracture is 224 meters whereas the distance of the cyclical fracture stands for 64 meters.As compared with the theoretical calculation results with the actual measured data on the spot,the preconditions of the calculation model of the mechanical model of the different distributive positions turns our to be correct and available,which helps us to disclose the reason accounting for the said surface crack is that the lingering length of near-surface igneous rock exceeded the safety lingering limit,which in turn leads to the near-surface rock fracture and the surface soil subsidy.Such a kind of danger area can be forecast and prevented by necessary preventive measures on the basis of the above theory and material support,which naturally suggests the indispensible value of the paper in preventing such and similar mining disasters.