LARGE SCALE UNDERGROUND EXCAVATING METHOD EMPLOYING TREANCH CUT PROCESS

PURPOSE:To improve safety of a landslide protection wall, by a method wherein, after both trench walls of a primary excavation part excavated in a trench shape are supported by a strut, the interior thereof is excavated in an open cut way in a manner that a part adjoining to the primary excavation part is left as it is. CONSTITUTION:In large scale underground excavation, such as gymnasia, a primary U-shaped excavation part 1 is excavated after landslide protection walls are built inside and outside, and sheet piles 7 and struts 2 prevent against damage due to an earth pressure produced by a bedrock 4. A secondary excavation part 5 for the interior is excavated in an open cut way, and a part, adjoining to the primary excavation part, is caused to remain as an internal landslide protection wall part 6. Further, after foundation concrete 9 is placed in the primary excavation part 1, soil at the internal landslide protection wall part 6 is discharged to complete foundation excavation. This causes the internal landslide protection wall part 6 to counter with the pressure of the bedrock, resulting in the possibility to improve safety of a landslide protection wall.