底板型冲击危险巷道深孔断底爆破防冲原理及实践研究

Theory and application of deep hole floor-break blasting in floor rock burst coal mine

通过采用弹性薄板小挠度理论对巷道底板受力分析,弄清冲击危险巷道底板冲击的主要影响因素,采用理论分析、数值计算相结合的方式研究断底爆破的防冲机理和优化方案,并对深孔断底爆破的防冲效果进行现场验证。研究发现,采动水平应力是造成巷道底鼓的主要原因,而底板的分层厚度、力学性质以及巷道两侧围岩的支护强度是巷道底鼓的主要影响因素。当底板岩层为致密厚质岩层时,当其断裂过程中所释放的弹性变性能会造成底板型冲击动力显现。深孔断底爆破其防冲实质为钻孔卸压法与振动爆破法防冲技术的有机结合。采用底板中部断底爆破与煤层断底爆破相结合的方式,不但可以释放底板内积聚的高应力,破坏其连续传递应力和积聚高能量的能力,也可使巷帮煤体的应力得到释放,卸压效果更为明显。

The small deflection theory of elastic thin plate has been used to analyze the roadway floor stress condition and the main influence factors of floor rock burst have been figured out. Theory analysis and numerical simulation have been used to study the rock burst prevention mechanism and optimization scheme about deep hole floor-break blasting and the control effect have been tested in practice. It has been found that the mining horizontal stress is the key reason for floor heave and the layer thickness of floor, and that mechanical properties and the supporting intensity of roadway surrounding rock are the main influence factors of floor heave. If the floor strata is dense thick mudstone, the rock burst will happen for the elastic deformation energy released in the process of floor layer broken. The essence of deep hole floor-break blasting is the combination of borehole pressure relief and blasting vibration method for rock burst prevention. When the position of blasting holes in the middle of the floor and roadway centre line, not only the high elastic deformation energy accumulated in the floor can be released and the ability of continuously transfer stress/ energy be destroyed, but also the high stress in the roadway side can be released, which has made the prevention effect more apparent.