摘要:
针对层状岩体隧道采用钻爆法施工过程中，爆炸能量分布不平衡易引起严重的超欠挖。以节理倾角和孔间延时及孔间距为主要影响参数，采用分层浇筑的方法制备了不同节理角度的模拟岩体试样，开展层状岩体爆破试验，基于ABAQUS模拟软件，分析层状岩体在不同节理倾角下爆破裂纹扩展及应力波传播特性。结果表明：节理倾角对应力波传播具有显著的导向作用，通过影响应力分布导致不同位置峰值应变及损伤程度的差异，进而促使裂纹在节理面处或炮孔周围扩展。孔间延时对裂纹扩展路径具有关键调控作用，随着延时增大，先爆孔与后爆孔的应力波叠加区域由节理中心逐渐向后爆孔周围转移，导致节理中心峰值应变与损伤值先增后减，岩体破坏区域相应向后爆孔偏移；但延时过长会削弱双孔应力波的协同效应。孔间距增大将减弱节理中心的应力叠加，使能量集中于炮孔周边，裂纹扩展模式从节理贯通转向孔周放射状分布；而过大的孔间距则因能量衰减与应力叠加不足，易导致孔间裂纹贯通失效，显著降低岩体破碎效率。研究成果对层状岩体爆破裂纹扩展的认识具有一定的帮助。
Abstract:
In the construction process of drilling and blasting method for layered rock tunnel, the unbalanced distribution of explosion energy was easy to cause serious over- and under-excavation. The joint dip angle, inter-hole delay, and hole spacing were the main influencing parameters. The simulated rock mass samples with different joint dip angles were prepared by the layered pouring method, and the blasting test of layered rock mass was carried out. Based on the ABAQUS simulation software, the blasting crack propagation and stress wave propagation characteristics of layered rock mass under different joint dip angles were analyzed. The results show that the joint dip angle has a significant guiding effect on the stress wave propagation. By affecting the stress distribution, the peak strain and damage degree at different positions are different, which in turn promotes the crack propagation at the joint surface or around the blast hole. The inter-hole delay plays a key role in regulating the crack propagation path. With the increase of delay time, the stress wave superposition area of the pre-blasting hole and the post-blasting hole gradually shifts from the joint center to the surrounding of the post-blasting hole, resulting in the peak strain and damage value of the joint center increasing first and then decreasing, and the failure area of the rock mass shifts to the post-blasting hole accordingly. However, too long delay weakens the synergistic effect of the double-hole stress wave. The increase of hole spacing weakens the stress superposition in the center of the joint, so that the energy is concentrated around the borehole, and the crack propagation mode changes from joint penetration to radial distribution around the borehole. However, too large a hole spacing is easy to lead to the failure of crack penetration between holes due to insufficient energy attenuation and stress superposition, which significantly reduces the crushing efficiency of rock mass. The research results are helpful to the understanding of blasting crack propagation in layered rock mass.
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