隧洞爆破开挖不可避免地会对围岩造成损伤,影响围岩稳定。以玉瓦水电站引水隧洞的钻爆开挖为研究对象,基于三维动力有限元(LS-DYNA)软件,对隧洞围岩在爆破开挖过程中的损伤演化过程进行了模拟分析,重点研究了围岩节理面和开挖程序对爆破损伤演化特性的影响。结果表明:节理面的存在抑制了垂直于节理面方向上的爆破损伤而促进了平行于节理面方向上的损伤演化;爆破开挖程序、循环进尺和单响药量均对围岩损伤有显著影响,施工中采用分层开挖、减小开挖循环进尺、控制单响药量等措施,能够有效地抑制爆破损伤。研究结果对控制隧洞超挖及确保围岩稳定具有重要指导意义。

Blasting excavation of tunnel would give rise to damage of surrounding rock inevitably. In this article, the damage evolution of surrounding rock during blasting excavation is simulated in LD-DYNA, a 3-D dynamic finite element software. The influence of jointed surface and excavation procedures on damage evolution are analyzed in emphasis. The headrace tunnel of Yuwa Hydropower Plant is selected for case study. Results show that during blasting excavation process, the damage perpendicular to joint surface is weakened, while the damage parallel to joint surface is exacerbated. Blasting excavation procedures, excavation footage and single dosage contribute to rock damage obviously, which however, could be weakened effectively if measures of layered excavation, footage decrease and single dosage control are taken. The research achievements are of guiding significance for reducing over-excavation and ensuring stability.