为解决滇西红层隧道支护变形风险高、单线小断面铁路隧道由于空间受限施工速度慢等问题，结合滇西红层以紫红色泥岩、砂岩为主，节理裂隙较发育，围岩强度适中等工程地质特征，依托大瑞铁路秀岭隧道进口平导，在滇西红层小断面隧道中引入悬臂掘进机施工，通过在适应性、设计参数等方面的深入研究，并与钻爆法在投资、施工进度、安全质量等方面进行对比分析，证明悬臂掘进机在滇西红层地区具有较好的适应性，具备较高的推广应用价值。应用研究结果表明: 1）悬臂掘进机适用于围岩强度适中、围岩（较）破碎、节理裂隙（较）发育以及地下水不（弱）发育的隧道； 2）悬臂掘进机对滇西红层围岩扰动小，初期支护可取消系统锚杆，并可以加大钢架间距； 3）悬臂掘进机在滇西红层隧道施工中进度优势明显，特别对于Ⅳ级围岩，进度较钻爆法提高了近67%； 4）悬臂掘进机早期资金投入较钻爆法高，且各级围岩条件下悬臂掘进机开挖单价为钻爆法的4～5倍。
The support deformation risk of tunnel in red beds in
west Yunnan is high, and the construction speed of singletrack
small crosssection tunnel is low because of space
limitations. The geological conditions of red beds in west Yunnan include
purplishred mudstone and sandstone, developed joint
fissures, and moderate surrounding rock strength. Accordingly, a boomtype roadheader is adopted in a small crosssection
tunnel of the pilot heading of Xiuling tunnel on DaliRuili
railway in red beds in west Yunnan. An indepth study
is conducted on the feasibility and design parameters of the boomtype roadheader, and it is compared with the drill and blast method
in terms of cost, schedule, and quality. The results show the following for the
boomtype roadheader: (1) Suitability for tunnels with
moderate surrounding rock strength, broken surrounding rocks, developed joints
and cracks, and insufficient underground water. (2) It mildly disturbs the
surrounding rock of red beds in west Yunnan; thus, the system bolt for primary
support can be eliminated, and the steel frame spacing can be increased. (3)
Superiority to other methods in red beds in west Yunnan in terms of
construction speed, especially for Grade Ⅳ surrounding
rock, the boring speed can be improved by approximately 67%. (4) A higher early
capital investment than the drill and blast method, with excavation cost per
unit of approximately 4~5 times that of the drill and blast method.
