Abstract: Dabaoshan Tunnel is located within the boundary of Shaoguan City, Guanydong Province. It is 431 meters long and 9 meters in clear width. Three-centered-circle arched wall is adopted in lining,and I-steel welded with stceel centering is used in the most complicared geologival zones to reinforce the lin-ing of the tunnel. In construction, special methods are used to treat the bad geological areas, shch as concrete spraying to seal the cracks, pressure grouting to consolidate the fracture zones, concrete pumping to packfill the lava tunnel, and building-in steel vail cover plate to span the lava channels. Now the tunnelruns effectively as a whole.

Key words: tunnel, surrounding rock, slide, sprayed concrete, pumping concrete, surrouding rock pres-sure, lava tunnel