Abstract: The Yuanshan tunnel, located in the seasonally frozen soil of a plateau area, is a shallow-buried tunnel in soft rock with a large section. It was originally designed to be constructed using the three-bench and seven-step method. Large deformations occurred during the construction due to the seasonal freeze-thawing, as the ground is mainly composed of carboniferous sandstone and mudstone classified as a grade V rock mass with abundant water. Based on a field sample test and theoretical analysis, the two-bench construction method with reserved core soil was adopted instead and some auxiliary construction measures were taken after a comprehensive comparison. As a consequence, the problem of large deformation during construction was successfully resolved, guaranteeing the safety and quality of the tunnel construction.