Soil Grouting to Arrest Foundation Settlement-Paper

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Five foundations supporting coke-transfer-car track beams and a dust-extraction pipe settled and tilted toward a nearby 12 m-deep junction-house excavation. Excavation spoil had been used as backfill and compacted inadequately, contrary to the design requirement for engineered or concrete fill. Settlements reached 111 mm and 126 mm at the two columns nearest the junction house. The reinforced-concrete members remained intact, indicating that the structure had tilted largely as a rigid body rather than suffered structural damage.<br /><br />Because equipment erection was underway, dismantling or underpinning with micropiles was impractical. Steel props and a load-spreading grillage were installed first to provide immediate support and reduce pressure on the affected foundations. The underlying loose backfill was then treated in situ by staged pressure grouting with cement slurry and admixture. Approximately 30 vertical and inclined grout holes were planned, with injection carried out in stages using packers. Settlement and grout consumption were monitored throughout the work.<br /><br />Settlements initially increased during grouting, likely as pressurized grout displaced soil, but subsequently stabilized. Final monitoring showed no continuing settlement, and deflection of the temporary steel props remained below 0.1 mm, indicating that the original foundations could adequately support the structure and equipment. Despite the soil’s borderline suitability for cement permeation grouting, careful design, execution, and quality control achieved the required stabilization without dismantling the structure or disrupting plant commissioning.

Keywords

foundation settlement

coke-transfer-car track beams

dust-extraction pipe

junction-house excavation

backfill compaction

tilt stabilization

steel props

load-spreading grillage

pressure grouting

cement slurry