Experimental Investigations on the Application of Compensation Grouting in Coarse-Grained Soils-Paper

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The study investigates how compensation grouting behaves in coarse-grained soils, where grout can penetrate pore spaces or be filtered, reducing the volume available to lift the ground.<br /><br />Researchers developed a soil filter press to assess grout performance for different soil–grout combinations. Tests showed that the effective grout fraction decreases as soil permeability increases, while reducing the grout’s water-to-solids ratio improves its effectiveness. The tested additions of clay, limestone powder and bentonite had little effect on the final effective fraction, though clay slowed filtration. The apparatus provides a practical way to compare grout mixtures before field application.<br /><br />A large-scale grouting test, involving up to 15 injection runs, measured ground heave and documented the fractures by excavation. The excavated fractures were generally about 0.5–1 cm thick and formed sheet-like structures. Early fractures were mainly vertical or steeply inclined; with repeated injections, they tended to spread horizontally and follow existing fractures. Repeated injections of smaller grout quantities produced broad, connected fracture structures, while larger quantities per injection created more branching fractures extending into previously untreated soil. The repeated-injection pattern was associated with greater heave.<br /><br />The findings clarify how grout properties, soil permeability and injection sequence affect ground movement. They can support more effective grout selection and injection planning, and inform future models for predicting compensation grouting outcomes in coarse-grained soils.

Keywords

compensation grouting

coarse-grained soils

grout filtration

soil permeability

effective grout fraction

water-to-solids ratio

soil filter press

ground heave

fracture propagation

injection sequence