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The challenges of remediating existing retaining walls and structures


Remediating existing retaining walls and structures that are either failing or showing signs of distress, can be a tricky business with a number of challenges and complications that are not present on a new build project.

Platipus Earth Anchoring Systems, distributed by Cirtex in Australia and New Zealand, are uniquely suited for remedial works and have over 30 years of proven experience and successfully implemented projects around the world.

Applications for utilising Platipus Anchors for holding down and slope stability solutions are endless, but one of the most versatile and often used applications for this system is providing remedial works and additional slope stability measures to existing retaining walls, structures, abutments and bridges.

The Platipus percussion driven mechanical anchor is a unique, modern and versatile device that can be rapidly deployed in most displaceable ground conditions. It offers a lightweight corrosion resistant anchor that can be driven from ground surface level using conventional portable equipment. It creates minimal disturbance of the soil during installation, can be stressed to an exact holding or tensile loading capacity and made fully operational immediately. As a completely dry system, it requires no messy grouting measures and provides minimal environmental impact!

The key challenges of remediating an existing wall or structure can be summarised as follows. Firstly, a housing or building development project may have difficult or confined site access to existing retaining walls and structures, secondly the architect has designed and detailed specific landscaping and aesthetic measures, and finally the wall will require remediation without disturbing the existing structure and thus eliminating costly dismantling or demolition works.

Restricted site access

Whether it is around the back of a house, down the side of a building or at the back of the commercial building block, old retaining walls are often difficult to access and reach. Platipus Earth Anchors can be installed with portable and readily available construction plant and equipment. Depending on the specification and size of a project, portable hydraulic hand breakers or small excavators are generally sufficient for installation purposes. Temporary drive rods to install the anchor systems are sectional and therefore allow for deep drives with a relatively short access area to work within.

Protecting established surroundings

Traditional anchoring systems rely on drilling and grouting, both are processes that can be detrimental to the environment. In an established mature landscaping area, both drilling fluids and grout measures can be detrimental to local flora and fauna. The Platipus percussion driven system simply installs by either static or dynamic force from the surface, thus minimising environmental damage and leaving the surrounding insitu soil and surface undisturbed.

Installation from the face

Whilst the effects of instability on a retaining wall or structure can be visibly seen at the wall face or slope surface, the problem and issue can often be found much deeper into the soil and embankment. Platipus Anchor Systems are driven from the surface into the structure and load locked and tested into a stable soil zone. This can address deep-seated slope stability concerns or slip failure issues without the need to excavate or remove the existing structure.

Remedial works to a strengthened reinforced earth embankment with polymer geogrid

This project was constructed without anchors 18 months ago and required further stability measures (post construction) to improve overall stability and long-term performance. Remedial works comprised of installing Platipus S6 ARGS Anchor Systems and Plati-Drains (to alleviate porewater pressure build up) up to depths of 4m. A durable Double Twist PVC coated galvanised mesh was applied to the steep slope faces and hydro-seeding and mulching measures used to facilitate vegetation growth and establishment. Resulting in a very successful outcome for the client.

Remedial works to a dry stone retaining wall

A dry-stone retaining wall, up to 2.5m in height and built in the 1960’s, was showing signs of bulging and failing. A Platipus Anchoring Solution, an alternative to completely demolishing and rebuilding a new retaining structure, was chosen as the preferred option delivering a cost effective and efficient solution. To stabilize the existing retaining wall, Platipus S8 Anchor Systems were driven up to 2m from the wall face and load locked and tested up to 15kN Working Loads. A highly durable Double Twist PVC coated galvanized mesh was placed and anchored to the existing wall face. Design life requirement for the remedial works was 40 years.

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Contact us here for a series of 3 short videos covering the Platipus system from the perspectives of concept, design and installation.