摘要
为解决隧道拱脚周边孔爆破难成形以致超挖和掌子面底部欠挖问题,研究了马蹄形隧道拱脚周边孔爆破围岩的损伤特征。依托方山隧道,建立了拱脚周边孔的三维数值模型,模拟了拱脚处围岩的损伤情况,分析了爆破效果与自由面形状、装药量以及空孔偏转角的映射关系,并通过现场试验进行了验证。结果表明:自由面形状显著影响围岩的损伤范围和炸药的能量利用率,相较于平直自由面,凹形自由面的损伤范围小,岩石的夹制作用更大,炸药爆破难以有效破碎围岩,能量利用率仅为78%;爆破效果随着装药量的增加呈先增大后减小的趋势,当拱脚周边孔的线装药密度为0.624 kg/m时,爆破效果最佳;此外,通过布设空孔和调整空孔偏转角,可以改善拱脚周边孔的爆破效果。采用优化后的爆破参数,拱脚处最大线性超挖量降低了53.1%,隧道轮廓成型平整。
To address the issues of over-excavation at the tunnel arch foot due to the difficulty of forming the perimeter hole blasting and under-excavation at the tunnel face bottom,the damage characteristics of the surrounding rock caused by perimeter hole blasting at the arch foot of a horseshoe-shaped tunnel were studied through a combination of theoretical calculations and numerical simulations.On the theoretical level,an in-depth analysis of the stress distribution and crack radius in the arch foot area was conducted based on the principles of blasting mechanics,and the theoretical charge length for the perimeter holes at the arch foot was derived.Building on this,a 3D numerical model of the perimeter holes at the arch foot was established through numerical simulation.During the modeling process,the damage evolution in the surrounding rock during blasting was simulated by introducing an appropriate damage model,along with the generation of post-blast damage cloud maps.By comparing the damage cloud maps under different conditions,the relationship between blasting effectiveness and parameters such as free surface shape,charge amount,and void deflection angle was analyzed,further revealing the mechanisms by which these parameters influence the blasting formation results,which were validated through field experiments.The research results indicate that the shape of the free surface significantly affects the extent of surrounding rock damage and the energy utilization efficiency of explosives.A concave free surface results in a smaller damage range compared to a flat free surface,with greater rock confinement,making it difficult for the explosives to effectively fracture the surrounding rock,leading to an energy utilization rate of only 78%.The blasting effectiveness shows a trend of first increasing and then decreasing with the increase in charge amount,with the optimal blasting effectiveness achieved when the linear charge density of the perimeter holes at the arch foot is 0.624.Additionally,by setting voids and adjusting the void deflection angle,the blasting effectiveness of the perimeter holes at the arch foot can be improved.With the optimized blasting parameters,the maximum linear over-excavation at the arch foot was reduced by 53.1%,resulting in a smooth tunnel contour.The research outcomes are engineeringly feasible and provide valuable insights for similar projects.
作者
徐帮树
杜念伟
王帅帅
周韧
高轩
张万志
XU Bangshu;DU Nianwei;WANG Shuaishuai;ZHOU Ren;GAO Xuan;ZHANG Wanzhi(School of Qilu Transportationg,Shandong University,Ji’nan 250000,Shandong,China;CCCC-SHEC Design&Research Institute General,Xi’an 710100,Shaanxi,China;School of Architecture and Civil Engineering,Xihua University,Chengdu 610039,Sichuan,China)
出处
《爆炸与冲击》
北大核心
2025年第8期174-186,共13页
Explosion and Shock Waves
基金
国家自然科学基金(50909056,52379102)
山东省自然科学基金(ZR2014EEM014)。
关键词
隧道爆破
围岩损伤
拱脚周边孔
凹形自由面
空孔偏转角
tunnel blasting
urrounding rock damage
perimeter holes at the foot of the arch
concave free surface
deviation angle of the uncharged hole
