Abstract:

he construction technology for the intermediate piles and columns has great importance for the cutandcover construction. It is particularly the case for the cutandcover topdown construction of extralarge deep foundation pits, where the construction of the intermediate piles and columns has fundamental importance for the safety and stability of the structures. Taking the construction of the intermediate piles and columns in the cutandcover topdown construction of the transportation hub works of Tianjin Railway Station as example, the author expatiates on the construction of the extradeep borehole cast piles, the construction of the steel pipe columns and concrete works and the settlement control of the piles and columns and discusses the development and research trend of the described technology in the paper.

Key words: extralarge deep foundation pit, cutandcover topdown method, intermediate pile and column, concretesteelpipe column, largediameter and superdeep borehole cast pile, construction technology, monitoring technology, hydrostatic level