Abstract: Metro station using cut and cover construction method often uses rolled steel reinforced concrete as the permanent and/or temporary supporting columns, but there are disadvantages such as complicated connection joints and difficult for the installation. In this paper, a single-story auxiliary structure constructed by the cut and cover excavation in a station of Tianjin Metro Line 6 is presented with a new type of rolled steel reinforced concrete composite column. The new structure is composed of concrete encased angle steel column. Some studs are welded on the outside of the angle and plate steel and the plate columns to improve the shear resistance, and some reinforced bars are placed in the concrete column. The longitudinal steel reinforcement bars of the beam at the beam-column joint pass through the angle steel gap of the concrete column, and the steel bars cut by the Angle steel are welded on the Angle steel and the fix plate, and the reinforcing longitudinal bars are provided. Rolled steel columns are also used as temporary columns to support the roof in the construction stage. After the foundation is excavated to the bottom, the composite column concrete is poured to form permanent columns. The connection method of the column joints optimizes the connection between the envelope structure and the connection joints. The field practice has proved that this method is convenient for the construction and reliable in quality control.

Key words: cut and cover excavation, rolled steel reinforced concrete, beamcolumn joints, subway structure