钻爆法施工隧道超挖分析研究

Analysis and Research on Tunnel Overbreak with Drilling and Blasting Method

采用钻爆法进行隧道开挖作业时,超挖是隧道施工时普遍存在的问题.在岩石的爆破破碎机理中,以冲击波反射拉伸理论和爆炸气体膨胀破坏理论综合作用占居主流地位.超挖不仅使支护成本增加,还会引起围岩局部应力集中,影响隧道的稳定性.对超挖原因的统计和国内外文献调查研究表明,其主要因素为钻孔精度、爆破技术和施工组织管理.为减少超挖,考虑地质因素和爆破因素的多元回归分析及人工神经网络等超挖预测模型被相继提出,其准确度明显优于前期的峰值粒子速度理论与块体理论.因此,在树立'少超少欠'观点的基础上,还要在提高钻孔水平、合理匹配爆破技术参数、提高施工管理和组织等方面采取一系列控制措施,从而达到减少隧道超挖的目的.

Overbreak is the common problem in the construction of tunnel when drilling and blasting are used. In blasting and crushing mechanism of rock, the combined effects of shock wave reflecting and stretching theory and explosion gas expansion and collapse theory occupy a dominant position. Overbreak will not only increase the cost of support, but also cause local stress concentration in the surrounding rock, thus affecting the stability of the tunnel. The results of statistics and literatures studies of home and abroad show that main overbreak factors are the drilling precision,blasting technique and construction organization management. In order to reduce overbreak, on the basis of geological factors and blasting factors, the multiple regression analysis and artificial neural networks of overbreak prediction models have been proposed, and its accuracy is superior to previous Peak Particle Velocity Theory and Block Theory. Therefore,in light of establishing the 'little overbreak and little underbreak' view, a series of control measures should be applied to achieve the target of reducing overbreak,such as improving drilling precision,matching reasonable blasting technology parameters and enhancing construction organization management.