City Structural were contacted by a Building Contractor to carry out a survey, and to design a repair specification for a long stretch of retaining wall in Bromley By Bow, London.
The retaining wall runs alongside a public walkway between the River Lee and the elevated Tesco car park. The wall holds back a huge volume of earth and is therefore under a great deal of stress. Over the years, these forces, along with environmental factors, including freeze-thaw, moisture, and vegetation, have caused outward bowing, cracking, and risk of collapse. Being alongside a walkway means that there was a risk of injury to the public.
Our repair specification comprised of a combination of 47 ground anchors, to anchor the wall to the earth behind it, along with masonry bed joint reinforcement to distribute the structural loads between the anchors. Several areas of the wall were rebuilt with the existing bricks prior to the anchoring and beaming.
The ground anchors are inserted horizontally, through core holes that are drilled through the wall. The grading of the retained soil determines the depth that the anchors are inserted, and the manufacturer’s recommendations indicated a depth of 3m. Once inserted to the correct depth, the drive rod is removed and a tensile load is applied to the tie bar. This causes the anchor to rotate vertically and lock into position for maximum load capacity. Square stainless-steel pattress plates are then fitted as an external anchor and terminated with a load nut.
The masonry bed joint reinforcement comprised of twin bands of stainless-steel helical bar inserted into three of the mortar joints along the entire length of the wall. As well as distributing the loads between the ground anchors, this reinforces the wall and provides additional resistance to further cracking and outward movement.
These works were successfully completed over a four week period and a ten year guarantee was given.
