Abstract：
A water transfer tunnel in hard rock with a small cross section, which was originally constructed by the full-face drill and blast method, suffered from a low advance rate and affected the construction schedule since the depth of the wedge cut hole was limited by the section width. In light of this setback, a new construction method was proposed. First, the pilot heading is excavated by advance blasting, and then the tunnel is enlarged by smooth-blasting. This paper details the construction procedures, cut hole pattern, blasting parameters, and testing results regarding the new construction method. The results show that, compared with conventional full-face excavation, the new construction method increases the advance rate, improves smooth blasting quality, and reduces construction costs significantly.
2013, Vol. 50 