隧洞底板开挖光面爆破实验

为了解决乌干达卡鲁玛尾水隧洞底板开挖的石方超挖问题,在底板开挖的初始阶段,进行了一系列光面爆破装药结构改进技术实验,通过调整底板光爆孔孔距、抵抗线、线装药密度,最终确定了合理的底板开挖光面爆破参数:孔距61.8cm,最小抵抗线60cm,装药间隔61.3cm,线装药密度160.4g/m。实验结果表明:光面爆破装药结构改进技术同样适用于隧洞底板开挖,底板光爆孔内按一定间距分布的炸药卷和导爆索在处于自由状态的情况下,仍然能够正常起爆。在卡鲁玛尾水隧洞底板开挖的光面爆破施工中,底板开挖半孔率达90%以上,底板总平均超挖16.67cm,大大减少了石方超挖量,节省了大量回填混凝土,有效降低了开挖成本。

Smooth blasting test in tunnel floor excavation

In order to reduce the overbreak in the tunnel floor excavation in Uganda Karuma HPP TRT Project,a series of trial smooth blasting with technical improvement of charging were conducted in the preliminary stage of tunnel floor excavation.The reasonable smooth blasting parameters were achieved by adjusting the blasthole spacing,burden and charging density.The blasthole spacing was 61.8 cm,burden was 60 cm and charging density was 160.4 g/m.It indicated that charging in smooth blasting with the technical improvement was applicable to the tunnel floor excavation,and the explosive and detonator installed with certain spacing in the blasthole could normally initiate without the fastening.With the smooth blasting in the tunnel floor excavation in Uganda Karuma HPP TRT Project,the half-hole rate reached more than 90％ and the average tunnel floor overbreak was controlled within 16.67 cm,which has reduced the overbreak and saved a lot of filling concrete to effectively reduce the cost of excavation.