节理岩体隧道爆破周边孔分区布设方法与应用研究

Research on Zoning Layout Method and Application of Contour Holes for Blasting of Jointed Rock Mass Tunnel

节理的存在会影响爆炸应力波传播,其走向与周边孔连的夹角和相对位置的变化会对爆破效果产生不同的影响。基于应力波在不同角度节理岩体中的衰减规律,提出了节理岩体隧道爆破周边孔分区布设方法,对节理与周边孔连线夹角为30°、60°、90°以及平行时的周边孔参数进行了优化。结合LS-PREPOST数值仿真和现场爆破试验,从岩体损伤深度和爆破振动速度方面对分区布设方法进行了验证。结果表明:通过对周边孔的分区布设,岩体的损伤深度与爆破振动速度明显优于原始周边孔布设方案。结合铜梁至安岳高速公路巴岳山隧道研究段地质条件,将节理与周边孔连线夹角为30°、60°、90°以及平行时的周边孔间距分别设置为43 cm、50 cm、58 cm、60 cm。爆破后平均超挖值可控制在18 cm,每延米混凝土超耗均控制在100%以内。研究结果为大断面节理岩体隧道爆破超欠挖控制提供参考。

The rock mass joints can affect the propagation of explosive stress waves.The angle between their direction and the surrounding holes and the relative position changes have different effects on the blasting effect.Based on the attenuation law of stress waves at different jointed angles,a method was proposed for zoning the surrounding holes of tunnel blasting in jointed rock masses.The parameters of the surrounding holes are optimized when the angle between the joint and the surrounding hole is 30°,60°,90°,and 0°(parallel).The zoning layout method was validated by combining LS-PREPOST numerical simulation and on-site tests regarding rock damage depth and blasting vibration speed.The results show that the rock mass′s damage depth and blasting vibration speed under the zoning arrangement of surrounding holes are significantly better than that of the original layout plan of surrounding holes.Based on the geological conditions of the research section of the Bayueshan Tunnel of the Tongliang Anyue Expressway,the angles between the joints and the surrounding holes are set to 30°,60°,and 90°,respectively.The spacings between the surrounding holes are set to 43 cm,50 cm,58 cm,and 60 cm when the joints parallel the surrounding holes.The average over-excavation value can be controlled at 18cm after blasting,and the over-consumption of concrete is controlled within 100%per linear meter.