Compensation grouting is the injection of cementitious grout beneath or beside a structure to correct or prevent settlement.
How does compensation grouting work?
Compensation grouting involves drilling an array of small-diameter tubes (called tube-a-manchette or TAM tubes) into the ground beneath or alongside a building or infrastructure asset. Through these tubes, a cement-based grout is injected at controlled pressures. As the grout fills voids and compresses the surrounding soil, it causes a small, measurable heave at the surface, compensating for any settlement that has occurred or is anticipated.
The process is typically guided by real-time monitoring using precise levelling instruments, inclinometers and automated data systems. Engineers can adjust injection volumes, pressures and locations in response to live deformation data, making the technique highly controllable.
Applications
Compensation grouting is most commonly deployed in urban environments where new construction activity risks damaging existing structures:
- Tunnel boring — counteracting ground loss above a tunnel alignment to protect surface buildings.
- Deep excavations — preventing adjacent structures from settling as soil is removed nearby.
- Historic building protection — maintaining the foundations of heritage structures during nearby piling or dewatering works.
- Utility diversions — stabilising the ground around sensitive pipelines or cables.
The technique is particularly valuable when conventional underpinning is impractical due to access constraints or where continuous, fine-tuned correction is needed over an extended construction period.
Related terms
- Foundation
- Concrete
- Reinforcement
- Mortar
- Construction
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