Model Test on Grouting Properties of Alluvial Filler Soil

Due to the complexity and untraceability of the grouting process and the underpinning of the slurry diffusion law, the current study on the grouting properties of alluvial filler soil lags behind the engineering application. Therefore, grouting model tests, including a laboratory soil test and a dynamic penetration test, are developed in this study to investigate the diffusion law of slurry and strength characteristics in alluvial filler soil. Through the excavation of the grouting model, the diffusion pattern of the grouting slurry can be observed precisely. Then an approach proposed in this study for estimating the shear strength growth of the grouting soil is verified by the grouting model tests. In addition, to assess the grouting volume, an analytical model considering the shrinkage coefficient of the slurry is developed. The good agreement between the test data and analytical results shows that the proposed method can effectively estimate the increase in shear strength and grouting amount. The excavation results show that the slurry is generally first filled and fractured along the interface between rock and soil and mainly fractured horizontally, with widths between 0.3~6.0 cm. The curves for the diffusion radius versus the distance from the grouting hole show a wavelike relationship in all directions (i.e., horizontal, up, and down).