为解决松散堆积体隧道支护变形大、爆破开挖风险高的问题，依托高原铁路某隧道进口段，采用悬臂掘进机两台阶法对松散堆积体软弱围岩进行开挖施工。结合左右线各约60 m长的开挖试验段，总结悬臂掘进机的开挖方案、施工进度、质量控制、安全环保等施工能力，并将其与局部爆破、挖机+破碎锤方法在变形控制和技术经济指标方面进行对比，分析悬臂掘进机的适用性。结果表明： 1）采用悬臂掘进机施工的隧道拱顶累计沉降量为20  mm、周边收敛为15 mm、线性超挖值为10~15 cm，均明显低于爆破和挖机带破碎锤方法的结果； 2）用悬臂掘进机施工每循环进尺1.2 m作业可节约2.5 h，Ⅵ级围岩进度可达到30 m/月，且洞内噪声较小、颗粒物质量浓度较低； 3）悬臂掘进机在洞口段堆积体以及Ⅴ、Ⅵ级和Ⅳ级偏软围岩具有较好的适应性，且适用于台阶法高度4.0～7.5 m、宽度5.5～8.5 m的断面开挖。

To solve the problem of large deformation of tunnel support and high risk of blasting excavation in loose accumulation, based on the entrance section of a tunnel on plateau railway, the twobench method using cantilever roadheader is adopted to excavate the weak surrounding rock of loose accumulation. Based on an excavation test section of about 60 m long on the left and right lines, the excavation plan, construction progress, quality control, safety and environmental protection, and other construction capabilities of cantilever roadheader are summarized, and the applicability of cantilever roadheader is analyzed by comparing with local blasting, excavator and breaker methods in deformation control and technical and economic indicators. The results show that： （1）The accumulative settlement using the cantilever tunnel method is 20 mm, the peripheral convergence is 15 mm, and the linear overexcavation value is ranged from 10 to 15 cm, which are significantly lower than the results of blasting and excavator with breaker. （2）2.5 hours can be saved for each 1.2 m footage of circulation, and the progress of Grade Ⅵ surrounding rock can reach 30 m/month；the noise in the cave is low, and the content of particulate matter is also low. （3）The cantilever roadheader has good adaptability in the accumulation body at the portal section and soft surrounding rocks of Grade Ⅴ, Ⅵ, and Ⅳ, and is most suitable for the section excavation construction with the height range of 4.0 to 7.5 m and width range of 5.5 to 8.5 m by bench method.