Originally Posted by kalifese
can you explain in english, williamchung
Normally, we build basement from underground to ground level. Top down construction is oppsite way. It basically build basement from ground level to underground. Engineer needs to stable underground soil by building retaining wall along the site. And then, workers will start building basement by excavate upper soil, and building beam, column and slab from top to bottom.This method is usually used in site that crowed by surrounding buildings, which open cut method could caused serious structural failure to adjacent buildings.
Some factors for choosing top down construction:
Lateral force of soil is uneven in this site
Foundation needs very deep excavation