Noida has been facing huge traffic issues due to construction. To construct such structures, Box Pushing Technique is developed where in RCC boxes in segments are cast outside and pushed through the heavy embankment of road by jacking.
The required thrust bed, as well as line & level of precast boxes are also controlled.
The Thrust bed and keys are designed in RCC to resist the required thrust exorted by jacking force and transfer it to soil at bottom and sides. Provision for jacking supports is made by providing suitable pockets in the bed to accommodate pin supports.
The Pre cast Box is cast in segments of convenient lengths of total pushing length. The Box section is designed as IRC codes of practice for loading.
The First Segment of precast box is provided with a specially designed structure named as Cutting Shield which forms the front working face with a cutting edge fabricated from MS plates and housed on RCC box section with suitable anchor bolts.
Necessary strengthening is provided by stiffeners and face plates of Box in front on completion of jacking the outer shell of the Shield is cut and removed.
As total length of Box is cast in segments, each segment is pushed turn by turn with necessary jacking force and so for this necessary intermediate jacking station are provided, with jacking pockets in bed & walls.
With the progress of jacking, the front unit with shield penetrates into the embankment and there after excavation within the shield is done manually of mechanically. The progress of pushing is kept continuous till total length is pushed.