中等砂化白云岩小断面隧洞控制爆破技术:以滇中引水工程玉溪段隧洞为例

Controlled Blasting Technology of Small Section Tunnel in Medium Sanded Dolomite:Taking the Yuxi Section Tunnel of the Central Yunnan Water Diversion Project as an Example

白云岩砂化是白云岩分布区一种特殊的岩溶地质现象,中等砂化白云岩岩体呈块状破碎结构,爆破以及超欠挖控制难度很大。为降低施工风险,减少超挖超耗,依托滇中引水工程扯那苴隧洞前段,开展了中等砂化白云岩小断面隧洞控制爆破参数优化研究。采用LS-DYNA软件,建立了砂化白云岩周边孔爆破模型,研究了不同光面爆破参数对岩体爆破裂纹扩展的影响,通过不同工况下的对比研究,提出了适用于中等砂化白云岩的光面爆破设计参数的合理取值范围。结果表明:周边孔间距取30~70 cm、径向不耦合系数小于2.6、最小抵抗线距离取30~60 cm、周边孔密集系数介于0.6~1.3时,爆破效果良好。在此基础上,总结形成了相应的控制爆破技术,施工效果与数值模拟结果吻合较好。

Dolomite sanding is a special karst geological phenomenon in the dolomite distribution area.The medium sanded dolomite rock mass is in a massive and broken structure,so it's very difficult to control blasting and over excavation.In order to reduce the construction risk and the over excavation and consumption,relying on the front section of Chenaju Tunnel of Central Yunnan Water Diversion Project,a study on the optimization of controlled blasting parameters for small section tunnel of medium sanded dolomite was carried out.The LS-DYNA software was used to establish the blasting model of peripheral holes in sanded dolomite,and the effects of different smooth blasting parameters on crack propagation were studied.The reasonable range of smooth blasting design parameters suitable for medium sanded dolomite was proposed.The results show that when the peripheral hole spacing is 30~70 cm,the radial uncoupling coefficient is less than 2.6,the minimum resistance line distance is 30~60 cm,and the peripheral hole density coefficient is 0.6~1.3,the blasting effect is quite well.On this basis,the corresponding controlled blasting technology is summarized,and the construction effect is in good agreement with the numerical simulation results.