Abstract: Jiulongjiang drilling and blasting tunnel is a small cross-section tunnel (3.0 m×3.0 m) with the shape of straightwall semicircle arch. Water gushing and sand boiling occurred frequently in the 180 m section of highly weathered granite during the construction, which was mainly caused by high hydraulic pressure and low strength of highly weathered rocks. In order to solve this problem, a series of comprehensive measures were taken, such as pre-grouting, shotcrete thickening and dewatering. And eventually, the tunnel was completed successfully. To verify the consolidation effect of these measures on soft surrounding rocks, the finite element software MIDAS GTS was used to analyze their structural state and engineering effect on surrounding rocks and supporting systems. It is shown that after pre-grouting is carried out, both concrete stress and surrounding rock deformation decrease significantly and the reinforcement effect of systematic bolts on soft surrounding rocks is limited. If the thickness of shotcrete layer is increased appropriately in a certain range, the compressive stress of concrete can be reduced significantly and loading capacity of surrounding rocks can be increased, and surrounding rock deformation and bolt force do not change greatly.