Rail
Challenge
A developing sinkhole beneath a live coastal railway threatened track stability, demanding immediate ground remediation with minimal operational disruption.
Solution
Geobear rapidly stabilised subsurface conditions using engineered geopolymer injection techniques, restoring ground integrity without excavation or prolonged possession requirements.
Emergency resposne
Void remediated
Material strength
Following the emergence of a sinkhole beneath a coastal railway embankment near Grange-over-Sands, immediate intervention was required to safeguard the operational railway. The void had developed beneath the existing track formation, creating the potential for progressive ground loss and compromising the support provided to the railway infrastructure.
Given the critical nature of the asset, the remediation strategy needed to deliver rapid structural stabilisation while avoiding extensive excavation, reducing possession requirements and limiting disruption to railway operations.
The project involved emergency treatment of a significant subterranean void beneath an operational railway where conventional excavation and replacement techniques would have introduced considerable programme, safety and logistical challenges.
The principal engineering challenges included:
The remediation required a solution capable of penetrating inaccessible voids while providing controlled expansion and immediate structural benefit without disturbing the surrounding formation.
Geobear designed and implemented an emergency geopolymer void remediation solution specifically developed for railway infrastructure applications.
Following site establishment by the principal contractor, specialist injection tubes were inserted directly into the void before a two-component expanding geopolymer was pumped through a self-contained injection system. The material mixed at the point of injection, rapidly expanding to occupy the entire cavity whilst exerting minimal additional dead load on the surrounding ground. The material cured in situ, forming a lightweight structural fill capable of restoring support beneath the railway.
The selected engineering material provided:
The installation utilised Geobear's mobile injection equipment, enabling material to be pumped remotely from a self-contained unit, allowing the treatment to be completed despite restricted site access. The entire emergency remediation was completed during a single working shift.

The emergency works successfully restored the integrity of the railway formation by completely remediating the underground void before further deterioration could occur.
Key project outcomes included:
The project demonstrates how engineered geopolymer technologies can provide rapid, technically robust solutions for emergency railway ground failures, significantly reducing programme duration and operational disruption compared with traditional excavation-based remediation techniques.
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