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

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The study investigates compensation grouting in coarse-grained soils, where grout can seep into pore spaces or be filtered, reducing the volume available to deform the soil and lift structures.<br /><br />Researchers developed a soil filter press to assess grout performance for different soil–grout combinations. Tests on sand and fine gravel showed that greater soil permeability reduces the effective grout fraction that causes deformation. Lower water-to-solids ratios improve effectiveness, while the tested additions of clay, limestone powder, and bentonite had little effect on the final effective fraction. The apparatus can help select suitable grout mixtures for site conditions.<br /><br />A large-scale grouting test simulated repeated injections, measured surface heave, and excavated the resulting fractures. The fractures were typically 0.5–1 cm thick and formed sheet-like structures. Early injections tended to produce steeply inclined or vertical fractures; with successive injections, fractures became more horizontal and often followed existing fractures. Repeated injections of smaller grout volumes created broad, layered fracture networks and produced more effective heave. Larger individual injections extended into previously untreated soil and formed more branch-like, slender fractures.<br /><br />The findings clarify how grout properties, soil permeability, and injection strategy affect compensation grouting. They may improve practical planning and support development of more realistic models for predicting grouting outcomes in coarse-grained soils.

Keywords

compensation grouting

coarse-grained soils

soil permeability

grout performance

soil filter press

surface heave

fracture network

sand

fine gravel

injection strategy