In LTM, whole enlargement process can be completed in the shortest period by using the bench cut. The upper and the lower half section of tunnel are blasted at once. However, different process of enlargement can be carried out respectively on the upper and the lower half section of tunnel, to reduce the cycle time of enlargement. By applying this concept to the enlargement process, stability of tunnel can be increased considerably, comparing this method with conventional drill and blast method. Thereby, the advance length of a blasting can be maximized without losing the stability of final tunnel.