某花岗岩隧道采用光面爆破开挖。为了改变爆破轮廓不平整以及超欠挖严重的问题,本文运用ANSYS/LS-DYNA有限元分析软件,建立径向不耦合系数k为1、1.25、1.5、1.75、2时的三维模型,探究径向不耦合系数对超欠挖的影响,并对现场爆破方案进行优化。通过比较5种不耦合系数工况下,炮孔底部的断面损伤,以及计算各个工况下的平均超挖值,发现随着径向不耦合系数增大,炮孔之间的贯穿能力逐渐下降。当不耦合系数k=1和k=1.25时,炮孔底部损伤区贯穿,且出现超挖;不耦合系数k=1.75和k=2时,损伤区没有贯通,难以形成光爆轮廓。综合来看,不耦合系数k=1.5时,能够达到良好的光面爆破效果。
A granite tunnel was excavated by smooth blasting. In order to address the issues of uneven blasting contour and serious over and under excavation, and explore the influence of radial decoupling coefficient on over and under excavation, this paper establishes a three-dimensional model when the radial decoupling coefficient K is 1, 1.25, 1.5, 1.75 and 2 by using ANSYS/LS-DYNA finite element analysis software. By comparing the section damage at the bottom of the blast hole under five conditions of decoupling coefficient and calculating the average overbreak value under each condition, it is concluded that the penetration capacity between the blast holes decreases gradually with the increase of radial decoupling coefficient. When the decoupling coefficient k=1, 1.25 and 1.5, the damage area at the bottom of the blast hole penetrates and overbreak occurs; When the uncoupling coefficient k=1.75 and k=2, the damage area is not connected, so it is difficult to form the smooth blasting contour. In general, when the uncoupling coefficient k=1.5, the over and under excavation can be effectively controlled to achieve an optimal smooth blasting effect.
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