预裂爆破作用下节理岩质边坡损伤区测试研究

Damage Zone Test of Jointed Rock Slope under Pre-split Blasting

随着我国大型露天矿开采深度的加大,高陡露天边坡的稳定性问题已经成为当前露天开采矿山亟待解决的关键难题,特别是在爆破载荷作用下,高陡边坡极易产生坡体表面岩体开裂甚至局部滑坡,为露天矿山开采带来了巨大安全隐患。为研究高陡节理岩质边坡在爆破载荷作用下的损伤特征,合理优化露天爆破参数,以太钢袁家村露天矿西边帮节理发育区域为工程依托,研究预裂爆破作用下节理岩质边坡的损伤区发展规律。采用数字钻孔摄像手段,测定爆破前后钻孔裂隙发育程度,测试结果表明:随着爆破距离的增加,岩体内部裂隙发育程度逐级递减,裂隙宽度逐渐减小,当距爆破点9 m以上,爆破对岩体裂隙无影响。采用爆破振动手段,监测围岩质点振动速度指标,监测结果表明:依据我国爆破振动安全标准,爆破损伤区范围不超过9 m。结合现场钻孔摄像和爆破振动结果,可得到袁家村露天矿西边帮预裂爆破的岩体损伤区范围为9 m。

With the increase of mining depth of large-scale open pit mine in China,the stability of high-steep open-pit slope has become a key problem in the current open-pit mines.Especially under the action of blasting loads,the surface rock mass cracking,and the high-steep slopes are prone to form the landslide hazard,which bring huge safety hidden trouble for open pit mining.In order to investigate the damage characteristics of high-steep jointed rock slope under blasting load and optimize open-pit mine blasting parameters.Based on the joint development area of the west slope of Yuanjiacun open-pit mine in Taiyuan Iron,the damage zone development law of jointed rock slope under pre-split blasting was studied.The digital drilling imaging method was used to measure the rock fracture development degree of the borehole before and after blasting.The test results showed that with the increase of the distance between test point and blasting hole,the development degree of crack inside the rock mass decreased step by step,and the width of crack gradually decreased.When the distance was more than 9 m,there was no effect on rock mass fracture for blasting.The vibration velocity index of the surrounding rock mass was monitored,and the results showed that the blasting damage zone also did not exceed 9 m.Combined with the results of digital drilling imaging and blasting vibration test,the rock mass damage area of pre-split blasting in the west slope of Yuanjiacun open-pit mine was in 9 m.