超前导洞在高地应力小间距隧道开挖施工中作用效果分析

根据兰渝铁路新城子隧道小间距段在开挖过程中出现严重大变形的工程实例，通过对小间距段左、右线在不同开挖方法下的现场监控量测数据及该段结构受力测试数据进行研究，并结合数值模拟计算结果分析，提出高地应力小间距隧道合理的施工方法。研究结果表明:针对高地应力区小间距隧道的开挖，采用应力释放洞法较台阶法能更有效地控制围岩变形，且支护结构所受到的围岩压力及内力均较后者小很多。

Effects Analysis of Pilot Heading in Excavation Construction of Small Spacing Tunnel under High Geo-stress

In relation to the project case with seriously large deformation arising in the excavation of small spacing section of Xinchengzi Tunnel on Lanzhou-Chongqing Railway, this section was studied in virtue of the measured data from the field monitoring at the right and left lines therein under different means of excavation and the stress testing on the structure thereof; then on the basis of numerical simulation, proper construction method for small spacing tunnel under high geo-stress condition was proposed. The result of study shows that, for the excavation of small spacing tunnel in high geo-stress region, stress release hole is the method controlling rock deformation more effective than bench cut method and, compared with the latter, the retaining structure exposes to far less rock pressure and internal force.