复杂破碎岩体矩形聚能药包预裂爆破试验研究

Experimental Study on Pre-splitting Blasting of Rectangular Shaped Charge in Complex Fractured Rock Mass

矿山靠帮作业中,确保节理裂隙发育地带的预裂爆破效果具有重要意义。为解决复杂破碎岩体预裂爆破效果差、半壁孔率较低的难题,以酒钢集团西沟石灰石矿西帮为例,结合炮孔特点及施工工艺,提出了一种聚能槽角度85°、药柱与孔壁之间约有13 mm空气间隔的矩形聚能装药装置,并分析了其聚能射流定向破岩机理;建立了聚能装置ANSYS/LS-DYNA数值模型,提取分析了沿聚能槽水平方向、垂直方向的监测点应力特征。研究表明:由于聚能药包的存在,调整了炮孔周边岩体应力分布状态,使得在与孔壁相同距离下,沿炮孔中心水平方向应力明显大于沿炮孔中心竖直方向应力,前者为后者的1.62~3.51倍,爆炸能量充分作用于聚能槽方向,使沿炮孔中心竖直方向(即被保护岩体方向)能量减弱,有效提高了聚能成缝效果。现场进一步试验结果表明:采用矩形聚能药柱预裂爆破区域半壁孔率为64%~82%,不平整度小于20 cm,远优于普通预裂爆破,验证了矩形聚能药柱装药结构的可行性,对于类似矿山具有一定的借鉴意义。

It is of great significance to ensure the pre-splitting blasting effect in the jointed fracture zone in the mine side support operation.In order to solve the problems of poor pre-splitting blasting effect and low half-wall hole rate of complex broken rock mass,taking the west side of Xigou Limestone Mine of Jiuquan Iron and Steel Group Co.,Ltd.as an example,combined with the characteristics of blasting holes and construction technology,a rectangular shaped charge device with an angle of 85°and an air interval of about 13 mm between the charge column and the hole wall was proposed,the directional rock breaking mechanism of the shaped charge jet was analyzed.ANSYS/LS-DYNA numerical model was established,and the stress of the monitoring points along the horizontal and vertical directions of the energy accumulation tank was extracted and analyzed.The analysis results show that due to the existence of the energy accumulation charge,the stress distribution of the rock mass around the blast hole was adjusted.Under the same distance with the hole wall,the stress along the horizontal direction of the center of the blast hole was significantly greater than that along the vertical direction of the center of the blast hole,and the former was 1.62~3.51 times that of the latter.The explosion energy fully acted on the direction of the energy accumulation tank,so that the energy along the vertical direction of the center of the blast hole,i.e.,the direction of the protected rock masswas weakened,and the effect of the energy accumulation seam was effectively improved.Further field test results show that the half-wall hole rate of pre-splitting blasting area with rectangular shaped charge is 64%~82%,and the unevenness is less than 20 cm,which is far better than that of ordinary pre-splitting blasting.The feasibility of rectangular shaped charge structure is verified,which has certain reference significance for similar mines.