Abstract: The support deformation risk of tunnel in red beds in west Yunnan is high, and the construction speed of singletrack small crosssection tunnel is low because of space limitations. The geological conditions of red beds in west Yunnan include purplishred mudstone and sandstone, developed joint fissures, and moderate surrounding rock strength. Accordingly, a boomtype roadheader is adopted in a small crosssection tunnel of the pilot heading of Xiuling tunnel on DaliRuili railway in red beds in west Yunnan. An indepth study is conducted on the feasibility and design parameters of the boomtype 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 boomtype 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.

Key words: boomtype roadheader, redbed tunnel in west Yunnan, adaptability, design parameters, drill and blast method