Study on Splitting Grouting Mechanisms in Sand Based on Nonlinear Compaction Effect

The splitting grouting in sand is a dynamic coupling process between slurry and soil. The slurry diffusion has the characteristics of invisibility, complexity and randomness. The research on the splitting grouting mechanism still needs to be strengthened at present. Through confined compression tests, the macro and micro structure characteristics and stress transfer modes of sand were explored. It was found that the particle fragmentation and clay particle content were the main factors inflerencing the compaction effect of sand, the particle fragmentation was positively correlated with the compaction effect, and the clay particle content was negatively correlated with the compaction effect. When the content of clay particles exceed the critical value, the macro and micro structure of sand would change qualitatively, and the nonlinear compaction effect was conspicuously enhanced. The nonlinear compaction process of sand was described based on a quadratic function model, which was characterized by the initial compression modulus E_t of sand and the ultimate strain ε_u under the final load, and the model was of a clear phyical concept and easliy measured parameters. The compaction effect of sand had a significant impact on slurry diffusion distance, splitting width and slurry pressure distribution. The splitting grouting analysis method considering the self-compaction characteristics of sand could further deepen the understanding of the mechanism for splitting grouting in sand.