Abstract: Grouting reinforcement is a common method to solve the liquefaction problem of water-rich sand soil in tunnels. Currently, traditional grouting materials have poor mechanical properties, low compressive strength, and high brittleness. There is relatively little research on the impact of the flow performance of grouting materials on the grouting reinforcement effect. This study designed a grouting reinforcement test for sand soil based on the rheological properties of grouting materials. Portland cement, fly ash, and polycarboxylate superplasticizer were used as raw materials, and high mechanical properties self-compacting paste was used as the grouting material for grouting simulation and on-site engineering tests. The study revealed the impact of the flow performance of grouting materials on grouting pressure, grouting diffusion range, and the mechanical properties of sand soil. The results show that self-compacting paste is an excellent grouting material with high compressive strength and high dynamic elastic modulus, and it has the characteristic of controllable flow performance. The slump flow of the paste is directly proportional to grouting pressure, grouting volume, and the lateral diffusion range of grouting. The viscosity of the slurry is inversely proportional to grouting pressure and vertical diffusion depth. Finally, improvement suggestions are proposed for the grouting method of water-rich sand layers from the aspects of single-hole grouting volume and grouting process. Self-compacting paste shows significant reinforcement effects in on-site grouting tests and is conducive to its wide application in the field of foundation reinforcement.

Key words: seismic liquefaction, water-rich sand layer, controlled grouting, self-compacting paste, diffusion law, foundation consolidation