# Model Test on Grouting Properties of Alluvial Filler Soil
## 9 Conclusions and Discussion  
In this work, the diffusion law of slurry and strength characteristics in alluvial filler soil were investigated by analytical methods and grouting model tests. Based on the Mohr-Coulomb yield criterion and Taylor series, this paper proposes an approach to estimate the shear strength growth of the grouting soil. In addition, an analytical model considering the shrinkage coefficient of slurry was also developed to assess the grouting volume. The following main conclusions were drawn:  
(1) The slurry is generally filled and fractured along the soil-rock interface and horizontal direction, and the width of the grouting veins is 0.3-6.0 cm. The slurry splitting channel is hollow and does not occlude during grouting. The width of the slurry splitting channel is 2.0-6.0 cm.  
(2) The curves for the diffusion radius versus the distance from the grouting hole showed a wavelike relationship in all directions (i.e., horizontal, up, and down). The diffusion radius first increases with the increase in distance from the grouting hole, then decrease with the increasing distance from the grouting hole after reaching its maximum at 30 cm from the grouting hole (i.e., quarter grouting pipe length).  
(3) According to the results of laboratory tests, the theoretical model for calculating the shear strength growth of grouting soil was consistent with the laboratory soil test results. It was reliable to predict the actual grouting volume by using the theoretical method, considering the slurry shrinkage coefficient.  
(4) This study proposed an approach to estimate the shear strength growth of the grouting soil and developed an analytical model considering the shrinkage coefficient of slurry to assess the grouting volume. The good agreement between the test data and computed results shows that the proposed methods can effectively estimate the increase in shear strength and grouting amount.  
In this study, the diffusion law of slurry and strength characteristics of alluvial filler soil were investigated by analytical methods and grouting model tests. However, the study of the laws and characteristics of other soil types is still an open question and remains challenging. To gain more insights in this regard, the work to apply the proposed approach to other soil types is currently ongoing. We will report more detailed results on this track in future submissions.  
Conceptualization, X.W.; methodology, X.W. and G.C.; software, X.W. and G.C.; validation, X.W.; formal analysis, G.C.; investigation, X.W. and G.C.; data curation, X.W.; writing--original draft preparation, X.W.; writing--review and editing, G.C.; supervision, G.C. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Graduate Innovation Project of Central South University (Grant No. 1053320192341).  
Not applicable.  
The authors express their appreciation for the financial support of the Graduate Innovation Project of Central South University (Grant No. 1053320192341). Meanwhile, the authors greatly appreciate [PERSON] for his valuable advice on the experimental program.