Ground Engineering
Repair and rehabilitation of failing retaining walls across New Zealand: MSE, gabion, concrete, pile, and historic stone structures, designed and built under one contract.
New Zealand's retaining wall stock is ageing, and failing walls on road corridors, private properties and development sites are an increasingly common problem. MSE walls with deteriorated geogrid are bulging and deforming. Gabion walls have lost fill and are collapsing. Concrete panel and soldier pile walls are cracking, tilting and overturning. Historic stone masonry walls (a significant part of New Zealand's road heritage) are eroding and collapsing. In most cases, the instinct is to demolish and rebuild. In most cases, that is unnecessary and disproportionately expensive.
GeoStabilization New Zealand Ltd specialises in the repair and rehabilitation of failing retaining walls, restoring structural performance in place without full reconstruction. Our SuperNails™ system installs high-capacity stainless steel soil nails through the face of the existing wall into competent ground behind it, restoring lateral resistance without excavation or demolition. Drainage improvement addresses the hydrostatic pressure that is often the root cause of wall movement. For historic stone masonry walls, stonemason-supervised repair preserves the original heritage fabric while restoring structural performance, an approach that satisfies both council requirements and community expectations.
REPAIR APPROACHES
GSI NZ CAPABILITY
THE GSI DIFFERENCE
Step 1
We assess the condition and failure mechanism of the existing structure: foundation conditions, drainage, loading, and the specific distress mode. This determines whether in-place repair, reinforcement, or replacement is the most appropriate and cost-effective solution.
Step 2
Repair solutions are designed for the specific wall type and failure mode. Typical approaches include soil nail and anchor reinforcement for MSE and gravity walls, gabion basket replacement or reinforcement, drainage installation to relieve hydrostatic pressure, shotcrete facing, and micropile underpinning for wall foundations experiencing settlement.
Step 3
GSI NZ engineers design the repair and our crews build it under one contract. Works are typically carried out with minimal traffic disruption, using compact equipment suited to constrained road and site environments. Full QA documentation and as-built records are provided on completion.
CASE STUDY
A flood-triggered landslide on Te Henga Road in West Auckland failed the road edge retaining structure and closed the eastbound lane. GSI NZ designed and built a permanent repair combining 27 steel-reinforced concrete bored piles at 5.4 m depth with a Geosynthetic Clay Systems retaining wall to restore full carriageway width, plus an integrated stormwater and drainage system to address the groundwater conditions that caused the original failure.
Works were completed through the winter wet season in an active slip environment, with Te Henga Road restored to full access in November 2024.
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Retaining structure repair and drainage remediation following a flood-triggered landslide, West Auckland.
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118 rock anchors and 790 m² TECCO mesh installed by helicopter and rope access.
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CFA piling and GCS wall on a constrained coastal site in Napier.
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A failing retaining wall only gets more expensive to fix over time. Our engineers will assess the failure mode and design a repair that lasts.
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