Study on Load Carrying Capacity of Top Down Prefounded Columns

Top Down 선기둥의 지지력 산정방법에 관한 연구

As underground construction is a large component of the cost of construction and a term of works in Top-Down construction, it is important to reduce the term of works in underground construction. The purpose of this study is to analyse buckling stress and load of prefounded columns as the process of excavation is changed, and propose a suitable process of excavation to increase the speed of works. When several floors are excavated, the valid buckling length of profounded column is increase and allowable buckling stress is decreased. The result shows that all columns are safe in buckling down to B3th story whether 2 stories or 3 stories are excavated straightly. However, several columns are not safe from B4th story when 2 or 3 stories are excavated straightly. With these results, a process can be designed that first B3 stories are excavated straightly, and then excavate B4th story putting concrete on B1st and B2nd story.