Abstract:

Technologies, such as setting up supporting system on the ground surface, prereinforcing the ground and separating the original piles by means of composite anchors, underpinning by cut piles, pile hole cutting with fullface grouting and bottom grouting, simultaneous lifting of the steel cap, boring parameters optimization, monitoring, simultaneous grouting and supplementary grouting, are adopted to control the settlement of the specialshaped plate zone of the existing bridge. In the end, the difficulties are conquered, the settlement of the existing bridge piles is less than 3 mm and the safety of the tunneling activities and the existing bridge is guaranteed.

Key words: shieldbored tunnel, crossing underneath existing bridge, specialshaped plate, underpinning, settlement control