Abstract: The depth of the foundation excavation of Zhoucun Station of Qingdao Metro Line No. 7 is large, and there are adverse geological conditions such as saturated sand layers and complex strata at the project site. The cast-in-place concrete pile has restrictive requirements for the borehole quality. Throughout the engineering experience and the analysis of the installation method of the bored piles with slurry wall and the long-cased drilling method, this paper proposes an application method of the bored pile with the long casing in the deep excavation support of the Qingdao Metro. The bored pile installation with long casing drilling is introduced in detail, including pile equipment set up, positioning and casing setup, positioning of the drilling rig, checking the casing plumbness, drilling in the soil, lowering of long casing, advancing and borehole cleanup, lowering the reinforcement cage, installation conduit, tremie concrete pouring, and lifting of steel pile casing.

Key words: Qingdao Metro, Saturated Condition, Composite Soil Strata, Long Cased Boring, Pile Installation