Bolts used in tunnel construction must be fully grouted so as to satisfy the technical requirements of shotcretingbolting support according to NATM (New Austrial Tunneling Method). In order to investigate the mortar grouting fullness and performance of combined bolts, trial application of combined bolts is made in the construction of Dabieshan tunnel. The trial results show that the construction process of combined bolts is reasonable, the combined bolts can be fully grouted and have almost the same construction efficiency as traditional mortar bolts and hollow grouting bolts. It is concluded that combined bolts should be recommended for tunnel construction.