# Resilient Modulus--Physical Parameters Relationship of Improved Red Clay by Dynamic Tri-Axial Test
## 5 Conclusions  
Due to the great difference in the physical properties of red clay in different regions, it is necessary to point out that the above predicted results are only applicable to the prediction of resilient modulus and improvement of red clay in Anhui province.  
1. The testing results showed that the dynamic resilient modulus of red clay can be obviously increased by adding cement or lime (3-9%). In addition, the dynamic resilient modulus increases with an increase in compactness and additive content, and decreases with an increase in moisture content. Testing results also showed that, when the contents of cement and lime in red clay samples were the same, the dynamic resilient modulus of red clay improved with cement was slightly higher compared to that improved with lime.  
2. Through a variance analysis of stress state, it can be concluded that the influence of deviatoric stress, and bulk stress on dynamic resilient modulus are significant, but the influence of deviatoric stress are more obvious. The dynamic resilient modulus of red clay increases with an increase in confining pressure. In addition, it decreases with an increase in deviatoric stress when the confining pressure is invariable, and increases with an increase in bulk stress when the deviatoric stress is invariable.  
3. Three existing prediction models were used to predict the resilient modulus of the improved red clay. A comparison of the predicted results, using these prediction models, indicated that the fitting performance of the Andrei model was the best. The resilient modulus is not only affected by the stress state, but also by the compactness, moisture content, and additive content. Therefore, based on the Andrei models, a new comprehensive prediction model was proposed to reflect the influence of compactness, moisture content, additive content and stress state on resilient modulus.  
Figure 8: Predicted resilient modulus versus measured resilient modulus at different optimum moisture content, compactness and cement by four prediction models (comprehensive model, [PERSON] model, NI model &Uzan-Witczak model). (**a**) 93% compactness and 6% cement; (**b**) optimum moisture content (OMC)and 6% cement; (**c**) 93% compactness and OMC.  
Figure 9: Predicted resilient modulus versus measured resilient modulus at different optimum moisture content, compactness and lime by four prediction models (Comprehensive model, [PERSON] model, NI model and Uzan-Witczak model). (**a**) 93% compactness and 6% lime; (**b**) OMC and 6% lime; (**c**) 93% compactness and OMC.  
By comparing the regression values with the measured values, it can be concluded that the new comprehensive prediction model has a good regression performance. The good performance applies to various additive contents, demonstrating a good potential of engineering application for the proposed prediction model.  
[PERSON] and [PERSON] conceived and designed the experiments; [PERSON] performed the experiments; [PERSON] and [PERSON] analyzed the data; [PERSON] wrote the paper.  
This research was funded by the National Natural Science Foundation of China (51874112;51774107), the Open Research Fund of State Key Laboratory of Geo-mechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences (Z013010), the Opening Project of State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology (No. KFJJ19-02M). All financial support is gratefully acknowledged.  
The authors declare no conflict of interest.