Construction Techniques for Caijiawan Hanjiang River Bridge on Wuhan-Yichang Railway

The main spans of Caijiawan Hanjiang River Bridge were designed as a rigid-frame continuous girder with span arrangement(64+120+168+120+56) m.The foundations for the main piers No.167 and No.168 of the Bridge were of the deepwater foundations that were constructed by the method of setting up platforms first and installing cofferdams late and the girder atop the foundations was cantileveredly cast by form travelers.4 types of boring machines were selected for use in the construction of the pile foundations in accordance with the different geologic conditions.For the pile foundations where the karst cavity presented,the ground there was handled by backfill of pebbles and clay.The pile caps were constructed by the double-wall steel boxed cofferdams that were lowered down in integrity by jacks.In the construction of the massive concrete for the pile caps,a series of temperature control measures like the layout of water-cooling pipes,prolonging of initial setting time of concrete and storage of water for curing were taken and the thermal cracking was therefore effectively prevented.The segment No.0 of the girder was constructed on scaffolding while the rest of the segments were cantileveredly and symmetrically cast by form travelers.At the closure gaps of the midspan of the rigid frame,the 4 000 kN jacking force was applied.