Pioneering Percussion Driven Earth Anchors (PDEA®) for 40 Years

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Hampstead, North London – UK

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Project Overview

This listed boundary wall located in Hampstead, North London, required a retaining solution after showing signs of overturning. The wall which is believed to be constructed in the early 1800’s was part of the boundary to the grounds of Cannon Hall. Platipus Anchors were appointed by the homeowner to provide a full Indemnified Design in relation to the refurbishment of a retaining structure. Suitability tests were conducted behind the wall, to verify the bearing capacity of the soil and finalize the anchor specification. A 120-year design life anchor solution was required, with bespoke facing load plates, to strengthen and increase the factor of safety of the wall against outward sliding and rotational movement. A drainage solution was also needed to reduce potential hydrostatic pressure from behind the wall.

Solution

Diamond core holes were drilled through the brickwork at 20° below horizontal for the ground anchors and slightly above horizontal for the Plati-Drain solution. Due to the location of the site, a temporary road closure was required for the main works to allow sufficient space to drive anchors to the 5m embedment depth using a BROKK 100 with a breaker attachment. Twenty-three B4 aluminium bronze anchors with stainless accessories were installed and proof tested to a maximum load requirement 21kN and then locked off at 14kN. In addition, seven S8 Plati-Drains were installed at the toe of the wall to remove the possibility of an accumulation of hydraulic pressure. Angles, driven depths, drive times and anchor performance were all recorded on an Anchor Installation Log, so that a Certificate Of Completion could
be issued as per the Indemnified Design.

Anchored retaining wall adjacent to road

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