Abstract:Taking 1 142 high stiffened columns in the Gangcheng Road Parking Lot of Shanghai Metro Line 10 as the engineering background, aiming at the construction challenges that are the difficulty in fixing the formwork caused by the dense longitudinal steel sections, insufficient compaction of concrete at column bases, and ineffective vibration by immersion vibrators due to the high single-pour height, the technology of double-layer square-round buckle fixation, secondary pressure grouting at the bottom of the column and attached vibration is innovatively adopted. This technology can effectively reinforce the column formwork by designing a new type of square-round buckle fastener. The grouting hole and vent hole system is pre-set to carry out the grouting of micro-expansive fine aggregate concrete, eliminating defects at column base joints. The attached vibrators are configured to vibrate layer by layer at intervals of 2 m, achieving the full-height quality control of 11.3-meter-high columns. The engineering application results indicate that the flatness of large-section columns meets the requirements, the appearance quality defects of concrete are relatively few, and the number of small holes per unit area is controlled at 54 per square meter. The ultrasonic wave velocity ranges from 3.605 to 4.200 km/s, and the compaction rate of column base joints reaches 100%. This innovated technology can provide a reference for the construction of stiffened structures in metro superstructure buildings.
