用垂斜截面仿预裂爆破法处理台阶断界的实践

Combining the Analogous Pre-split Blasting with Vertical Oblique Section for Breaking Hard Rock Platform

露天矿坚硬岩台阶深孔爆破断界常见但其相关技术研究较为少见。吉朗德露天煤矿在台阶断界处先后采用过垂直截断面爆破开挖断界法和垂斜截面爆破开挖断界法,爆破质量差,紧邻保留区岩体拉裂损伤严重,开挖后不能形成规整断界轮廓面。结合垂斜截面构状(半"V"形构状面)有利于岩石台阶爆破外推和预裂爆破有止裂、减振的作用而提出垂斜截面仿预裂爆破断界法(断界斜线长15 m,爆破外推倾角为130.6°,仿预裂炮孔7个,孔径120 mm,孔深12 m,孔距2.5 m,相邻炮孔间呈互耦状间隔装药,先于主爆区110 ms齐爆)来处理该矿坚硬岩台阶断界工程问题,爆破效果好,开挖后易于形成规整轮廓面,消除了保留区后续钻爆施工隐患,为坚硬岩台阶断界提供了典型工程实例参鉴。

The working conditions of deep-hole blasting for breaking hard rock platform are common,but the relevant technical reference is relatively rare for open-pits. The blasting quality of the conventional vertical section blasting excavation cut-off method and vertical inclined plane blasting excavation cut-off method are both poor for breaking hard rock bench in Girander Mine. Vertical oblique section is conducive to the extrapolation,and the pre-splitting blasting is beneficial to dampen and stop crack,therefore the analogous pre-split blasting with vertical oblique section was proposed to breaking hard rock platform. Practices in Girander Mine(the blasting slash length was 15 m,the pre-split bevel was 130.6°,the number of pre-split holes was 7,the diameter of pre-split holes was 120 mm and 12 meters deep,the distance was 2.5 m between pre-split holes,the pre-split holes were charged with mutual coupling,delaying 110 ms before the main explosion area)showed that the blasting quality was more excellent,the construction cost was lower. A regular contour surface was formed after the excavation,eliminating the hidden dangers of construction in the reserved area,and providing a typical case for breaking the hard rock step.