Study on Arrangement of Advance Heading for Extra-long Double-barrel Single-track Tunnel

The position of advance heading directly affects the difficulty of opening cross adits, the degree of secondary disturbance to the rocks caused by drilling and blasting, and the volume of construction ventilation and drainage. In this paper, the construction plan of "advance heading (for later enlargement)" of the extra-long double-barrel single-track tunnel is taken as the background, and the position of advance heading and the effect of controlling rock deformation by heading is emphatically studied. According to the study results, it is suggested that the heading should be located at the middle lower section of the tunnel. First, it is beneficial to set up the cross adits to assist the tunnel excavation for Track I. Second, it can be used as the construction drainage and ventilation channel to reduce the length of the counter-slope drainage section and lower the ventilation and drainage volumes during construction. At the same time, advance heading has unloading effect, and the effect of controlling the rock deformation of the tunnel is remarkable.