Sustainability Assessment of Deep Foundations: Case Study-Paper

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The paper presents a cofferdam method used to construct water-based well foundations for the 1,400 m Narmada River railway bridge in Gujarat. The bridge has 30 well foundations; 13 river piers required a dry working area despite daily tidal variations of 3–4.5 m.<br /><br />Instead of conventional, costly steel caissons, the team created temporary “dry islands” around the foundations using circular cofferdams. Each 16.2 m-diameter system combined 1,500 mm steel liner piles with sheet piles, supported by struts or walers and filled with sand. This enabled well construction using land-based methods.<br /><br />Design was based on site-specific geotechnical and hydrological conditions. WALLAP software was used for staged analyses of soil and water pressures, including construction loads and surcharge from the well curb and steining. The analysis assessed wall forces and deformations, and the liner and sheet-pile sections were checked for strength. The authors emphasize that performance is sensitive to soil stiffness and that cofferdam founding levels must account for local scour.<br /><br />Construction involved positioning barges, driving the piles with a vibro hammer, installing supports, placing sand fill, and then forming and concreting the well foundation. The cofferdams could be installed ahead of foundation construction.<br /><br />The method substantially reduced temporary steel quantities and construction time compared with caisson construction, while allowing foundations to be built in a safer, dry environment. The paper concludes that careful design and selection of pile founding levels are essential to the system’s reliability.

Keywords

cofferdam

well foundation

Narmada River bridge

steel liner piles

sheet piles

dry working area

WALLAP analysis

hydrological conditions

soil stiffness

bridge construction