新乌鞘岭隧道软岩大变形悬臂掘进机施工控制技术研究

为解决新乌鞘岭隧道8号、9号、10号斜井工区正洞在千枚岩、板岩等软弱破碎岩体前期施工中出现的掌子面频繁溜塌、初期支护开裂、变形扭曲等问题，在对地质预报、监控量测和围岩松动圈等数据分析以及三台阶钻爆法施工支护存在的问题研究的基础上，采用现场试验的方法，研究玻璃纤维锚杆超前加固、超前大管棚支护、悬臂掘进机预留核心土两台阶机械法开挖工法、合理预留变形量以及增强初期支护的锁脚锚固、桁架结构加强初期支护纵向连接、径向注浆加固围岩等措施。经现场应用表明： 1）对于高地应力软弱围岩隧道，采用预留核心土两台阶大断面悬臂掘进机铣挖法施工技术是可行的，结合超前加固、支护结构补强等措施后，支护结构累计变形较前期减小一半以上，支护结构变形可控。2）采用悬臂掘进机开挖，隧道平均线性超挖量可控制在15 cm以内，相比钻爆法喷射混凝土平均超挖率由120%减小至60%，工序循环时间减少3 h左右，月施工进度由25~35 m提升至50~60 m。3）高地应力软岩大变形控制应在合理工法、合适设备、合理预留变形量和具有一定抵抗变形能力的支护结构之间找到平衡点。

Control Technology of Soft Rock Large Deformation in New Wushaoling Tunnel Induced by Cantilever Excavator Construction

During the main tunnel construction at the inclined shaft site Nos. 8, 9, and 10 of the New Wushaoling tunnel in phyllite and slate soft and broken rocks, many challenges were faced, such as the frequent collapse of the tunnel face, primary support cracking, and rock mass deformation and distortion. Accordingly, the data analysis of geological prediction, monitoring measurement, surrounding rock loose circle, construction stage, and support problems in drill and blast construction of the three bench method is studied. The field test method is used to study advance reinforcement using glass fiber anchor rods, advance large pipe shed support, two bench mechanical excavation method for reserving core soil by cantilever excavator, reasonably reserved deformation, foot locking anchorage enhancing the primary support, truss structure strengthening the primary support longitudinal connection, radial grouting, and surrounding rock consolidation. The field relevant results show the following. (1) The reserved core soil two bench large section mechanical construction using a cantilever excavator is feasible in soft rock tunnels with high ground stress. After using the advance reinforcement and support structure methods, the stabilizing period of support convergence is reduced by over a month. The support structure′s accumulative deformation is reduced by approximately half compared to the early phase, showing a controllable deformation trend. (2) The average linear over excavation using a cantilever excavator can be controlled within 15 cm, reducing the average over excavation by approximately half of that by drill and blast methods (from 120% to 60%), reducing the construction cycling time by 3 h, and improving the construction efficiency from 25~35 m per month to 50~60 m per month. (3) Large deformation control of soft rock with high ground stress should balance reasonable construction methods, equipment, reserved deformation, and support structures with specific deformation resistance.