Diaphragm Wall Methodology

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SERVICE CORRIDOR IN MIDDLE CIRCLE TOP DOWN METHOD OF CONSTRUCTION

Transcript of Diaphragm Wall Methodology

Page 1: Diaphragm Wall Methodology

SERVICE CORRIDOR IN MIDDLE CIRCLE

TOP DOWN METHOD OF CONSTRUCTION

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TOP DOWN METHOD OF CONSTRUCTION

Service Corridor, being made in Middle Circle of Connaught Place is a tunnel of box section of size (6.3 x 7 mtrs)

Top Down Method of excavation adopted for the project as deep excavation was to be carried out very near to existing buildings

Work being carried out by M/s Afcons

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STEPS OF TOP DOWN METHOD

Identification of Existing Utilities Shifting of Utilities & Making of Guide Wall Boring for Diaphragm Wall up to the required depth Lowering of R/F cage in the Bored Area Concreting of the Diaphragm Wall Panel Excavation & Chipping of Concrete up to the cut-off level RCC Top Slab for the Service Tunnel Excavation up to the Bottom Slab

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Identification of Existing Utilities

Making of Pre-trench across the road at regular intervals to identify the utilities running along the Proposed Service Tunnel

After the utilities were identified, methodology for shifting of these utilities were finalized

Pre – Trench showing the existing utilities

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Shifting of Utilities & Making of Guide Wall

The identified utilities were diverted temporarily so as to keep the utilities running & also to make a guide wall for the boring

A Guide Wall was constructed for a depth of 1.6 m along the alignment of Service Corridor – to assist in boring for Diaphragm Wall & to shift any unforeseen utilities which are layed across the road & have not been identified in the pre-trench

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Boring for Diaphragm Wall

Boring done up to a depth of 14 m

Boring done with the help of bentonite slurry to help stabilize the walls of the boring till concreting is done

The grab is tied to the body of the crane as a safety aspect to prevent it from hitting any existing building

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Lowering of R/F Cage

• R/F Cage for Diaphragm Wall Panels of Size (5.0 M) made ready before boring is commenced

• Each R/F cage weighs approximately 10.5 MT

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Concreting for Diaphragm Wall

Tremie Concreting done for Diaphragm Wall

Each Diaphragm Wall Panel is 56 cum

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Excavation up to Bottom of Top Slab

After the Diaphragm Wall is casted, Excavation for bottom of top slab is taken up, so that the inconvenience to the public is minimum.

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Top Slab

A top slab of 600 mm is casted, leaving openings at regular intervals, so that excavation inside the tunnel can be carried out

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Excavation for Base Slab

After the top slab is casted, excavation inside the tunnel is started for base slab works

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Utilities Encountered and Shifting

• The identified utilities were diverted temporarily so as to keep the utilities running & also to make a guide wall for the boring ,these included electrical cables, communication cables, drainage sewerage etc.

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FACILITIES INSIDE SERVICE TUNNEL

HT cables LT cables Telecommunication cables Water supply pipe Fire water pipes -one for hydrant network system and another for

water sprinkler systems; tapping to be taken from the latter for providing water spray protection inside the trench.

Irrigation pipeline Gas pipeline. Air conditioning pipes (chilled water) –one for supply & one for

return to the entire Connaught Place areas including P Block, Regal Block & Scindia House Block. Secondary pumping system (one working & one standby) and two heat exchangers required for individual blocks are to be provided in the tunnel

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THANKING YOU