Study on increase in stability of floating and underground extension method through slab pre-construction

The development of underground spaces in urban areas plays a crucial role in the regeneration and sustainability of cities. However, the conventional underground excavation works in metropolises limit the use of the ground facilities owing to stability, noise, and vibration problems, which may cause huge economic damage. In this study, a method of pre-constructing slabs of underground facilities was analyzed to improve the stability of the floating and underground extension method, even during the use of the target building. First, a numerical simulation was conducted to compare the stability of the top-down method with slab pre-construction with that of the conventional top-down method. Then, the stability of the test bed was checked by applying this construction method to the field. As a result, the top-down method with slab pre-construction significantly improved the stability of the target building by preventing the buckling of the columns and supporting members. The increase in the displacement of existing columns and supporting members was controlled after the pre-construction of the slab. In addition, the crack width and ground settlement were stable within the management standards at the field. Thus, this construction method is expected to be crucial in pursuing urban regeneration and sustainability through the efficient development of underground spaces.