Queens Elms - Retaining Wall
RETAINING WALL SUCCESS TAKES ACHESON & GLOVER TO NEW HEIGHTS
Segmental retaining walls [SRW’s] have helped reduce cost and speed the building of the new student accommodation blocks at Queens University’s, Elms Village site at Malone Road , Belfast .
Steven Hook, European Business Development Manager for retaining wall specialists, Anchor Wall Systems Inc, takes a look at the Elms Village project and explains why segmental retaining walls are set to take off in the UK construction market.
Background
The Elms Village site is a brown-field, city centre development that replaces a collection of 1960’s tower blocks and is being built to provide an attractive village type environment to house over 1500 university students.
Poor ground conditions and challenging site topography meant that new building-levels for many of the 29 accommodation blocks had to be created by introducing bold terracing, enclosed within a series of engineered retaining walls.
Conventional in-situ retaining walls would have needed temporary sheet piling to protect the working area during construction together with substantial concrete foundations, both of which would add to costs and slow down the building schedule.
As the retaining walls had to be designed and installed as the site progressed and the old accommodation blocks were being demolished, the need for a flexible system that would cope with curves and slopes was paramount.
The Architect’s perspective
Simon Robinson of Belfast based Architects, Robinson & Patterson, who acted as a Single Appointment, Project Management team for the Client, Queens University , explained his reasons for using the system.
“From the word go, it was a very challenging project. The client wanted a village type environment that was more conducive to study. Disruption to student residents during the 5 year build period had also to be kept to a minimum.
The site was difficult with lots of cross-falls and inherently unstable ground conditions. To get the required number of blocks on the site and provide unrestricted wheelchair access, we had to create a series of flat and level building pads. This involved re-contouring the site and the installation of retaining walls up to 4.0m in height.
We considered cast in-situ retaining walls with decorative facings and crib walling but both were rejected in favour of Segmental Retaining Walls on a cost and practicality basis.
In-situ was too restrictive and couldn’t cope with the complex curves. It was also a more costly solution and it would have been difficult from a safe- working standpoint for the contractors. Crib walling required too much land-take and this method also couldn’t accommodate the curves.
The Anchor solution gave us the flexibility we needed, they were easy to design with and precise wall routes, levels and curves could be adjusted easily, if needed, as the site progressed.”
What is an Anchor Segmental Retaining Wall?
The Anchor Vertica Walling used at Queens University , is a dry built, segmental retaining wall system made up of concrete facing blocks that work together with polymeric geogrids and compacted back-fill to form a highly efficient, engineered retaining wall. The Anchor system does not require concrete foundations so temporary shuttering is not needed to retain the excavation while the concrete footings of conventional walls are allowed to cure.
Because of their modular nature, Anchor systems enable the design and construction of tight curves and corners in difficult access situations. They require less skilled labour and plant than many alternative options which means they can be installed quickly and cost-effectively. In addition, they are aesthetically appealing and reliable and offer excellent design life and performance.
The Anchor system also has positive environmental credentials and these were well illustrated at the Queens University scheme. Much of the excavated Malone sands could be reused as structural back-fill to the retaining walls so spoil removal and the vehicle journeys that go with it were reduced and imported stone was kept to a minimum.
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