Case Study: Permanent Sheet Pile Basement, One The Square

Permanent Sheet Pile Basement, One The Square

Sheet Piling (UK) Ltd. were employed by Wates Construction to install a permanent watertight basement to enable the construction of a single underground car park for a high profile mixed retail and residential development adjacent to Cambridge Railway Station.

Having reviewed the design drawings and specification, which included a Highways Approval in Principal, Sheet Piling (UK) Ltd provided an in-house design solution using our highly experienced and competent Design Team.

The solution consisted of adopting highly structurally efficient ‘Z’ shaped sheet pile sections which permitted predominately a cantilever solution to be adopted to facilitate excavations to a depth of approximately 4.0m whilst complying with the specified deflection limit of 20mm.

For localised greater excavations of up to 6.0m, Sheet Piling (UK) Ltd provided a temporary bracing solution utilising the reinforced concrete capping beam as a waling beam with the horizontal struts removed once the basement slab had been cast.

Again, this demonstrates the design benefits of structurally efficient ‘Z’ shaped sheet piles in providing design and construction solutions for basement construction whereby the overall construction methodology is extremely simple.

The overall basement perimeter was approximately 290.0m and the scheme involved the installation of 460no 9.0m & 10.0m long Emirates Steel EZ18-630 sheet piles.

The sheet piles were installed using 2no Giken Silent Vibrationless Pile Presses over a 4no week installation programme period.

Ground conditions on site consisted of Made Ground over Medium Dense Sands and Gravels over London Clay. The piles were installed without the need for preaugering, but water jetting techniques were employed to reduce resistance during pile driving.

The works were successfully completed in September 2015 including all clutch welding and bracing removal.