Ground improvement and stabilisation to support new sewer beneath motorway

Challenge

Construction of a new sewer beneath a live motorway required ground improvement to ensure stability and load performance without disrupting traffic or compromising safety.

Solution

Geobear delivered targeted geopolymer injection to strengthen soils around the sewer alignment, improving bearing capacity and maintaining motorway integrity during and after installation.

Live motorway environment

Works delivered under traffic constraints

Targeted ground strengthening

Support to new sewer alignment

Rapid curing solution

Minimal impact on programme

Background

A new sewer installation beneath a motorway required assurance that surrounding ground conditions could safely support both the pipeline and overlying traffic loads.

Weak or variable soils presented a potential risk to long‑term performance, making ground improvement a critical element of the scheme.

Challenge

Traditional ground replacement or large‑scale stabilisation would have introduced programme delays, significant excavation and potential disruption to motorway operations.

A precise, low‑impact solution was required to improve soil strength in situ while maintaining safety and traffic flow.

Solutions

Geobear designed a controlled geopolymer injection programme to enhance soil stiffness and bearing capacity along the sewer alignment.

Small‑diameter injection tubes were installed to introduce a two‑component geopolymer into targeted zones. The material expanded on mixing, filling voids, binding loose soils and increasing load‑bearing performance.

Injection parameters were carefully managed to ensure uniform improvement while protecting both the new sewer and the motorway structure above.

Results

Ground performance was enhanced, providing long‑term stability for the sewer installation and overlying carriageway.

The works were completed efficiently within a live motorway environment, delivering a durable and lower‑carbon alternative to traditional stabilisation methods.

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