Mass Gravity Retaining Walls
2003
Belfast, Northern Ireland
Queen's University
O'Hare & McGovern Ltd
Maccaferri Ltd
Queen’s Elms Student Village
Problem
Founded in 1845, Queens University now has 24,000 students. In keeping with this prestigious seat of learning, the University wished to replace a collection of 1960’s 1960s-style tower blocks with an attractive village-type environment to house over 1500 students. Poor ground conditions and challenging site topography meant that new building levels for many of the 47 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.
Solution
The MacWall system, specified by Robinson and Patterson, solved these problems because of its speed of installation, flexibility and ease of construction without the need for complex formwork and shuttering MacWall is a dry-built, segmental retaining wall system comprising concrete facing blocks in conjunction with soil reinforcing geogrids and compacted back-fill to form a highly efficient, engineered retaining wall. Unlike conventional retaining walls, MacWall does not require concrete foundations or the temporary shuttering that would be required to retain concrete footings of conventional walls are allowed to cure. This speed of installation meant that the underlying “Malone” sands, a feature of the Queen Elms site, could be excavated and the wall installed before the ground weakened and collapsed.