基于Hoek-Brown方程的边坡光面爆破参数设计方法

摘要

The current experiential methods for the design of slope smooth blasting parameters are not able to illustrate the strength characteristics of slope rock mass.Based on introducing rock point load strength index and the Hoek-Brown empirical equation of rock mass strength,the formulas for the uniaxial compressive strength and tensile strength of rock mass were obtained.Then,the formulas were deduced for the spacing between blasting holes,the vertical distance from the smooth blasting hole to the bottom of the main blasting hole (the minimum resistance line),the coefficient of decoupling charge and the linear charge density.These formulas were applied to design the slope smooth blasting parameters of rock cutting for the new-built railway from Nairobi to Malaba in Kenya.Project implementation results indicate that the trace rate of the rock slope blasting hole in strong and weak weathering sections is about 56％ and 85％ respectively.The maximum value of over under-excavation is about 16 cm,and the entire excavation reveals a smooth contour line.The blasting effect is very ideal and the correctness of these formulas is verified.%针对目前边坡光面爆破参数设计中经验方法未能反映边坡岩体强度特性的问题,引入岩石点荷载强度试验指标,并基于Hoek-Brown的岩体强度经验方程,得到岩体单轴抗压和抗拉强度的计算公式;进而推导岩体边坡光面爆破钻孔的孔间距、光面爆破钻孔距主爆孔孔底的垂直距离(最小抵抗线)、钻孔装药不耦合系数和钻孔线装药密度的计算公式.在肯尼亚的内罗毕至马拉巴新建标轨铁路工程中,应用这些计算公式进行岩体路堑边坡光面爆破参数的设计,工程的实施结果表明:强风化和弱风化段岩体边坡炮眼痕迹率分别约为56％和85％,坡面超欠挖量最大值约为16 cm,整个开挖轮廓线型流畅,爆破效果十分理想,验证了这些计算公式的正确性.