# Model Tests of Soil Reinforcement Inside the Bucket Foundation with Vacuum Electroosmosis Method
## 5 Conclusions  
The influence of vacuum pressure, the electrodes, and electrification mode on the strengthening of soil in a bucket foundation was examined using model tests of vacuum electroosmosis reinforcement. The effects of reinforcement on foundation settlement, water discharge, and undrained shear strength were evaluated. Finally, model tests on bearing capacity of the bucket foundation before and after soil  
Figure 16: Horizontal load versus displacement.  
Figure 17: Rotation center height versus horizontal displacement: (**a**) TH1; (**b**) TH2.  
Figure 15: Failure mode of horizontal load.  
reinforcement were carried out, and the effects of soil reinforcement on the bearing characteristics of the bucket foundation were analyzed. The following conclusions are made:  
1. The vacuum electroosmosis reinforcement significantly improves soil strength inside the bucket foundation when using the bucket wall as the anode, and undrained shear strength increases with increasing the voltage. The undrained shear strength of the soil applied the voltage of 20 V is 3-4.5 times that applied the voltage of 3.75 V in this study. Furthermore, a higher driving voltage can improve the uniformity of soil reinforcement in the vertical direction. The vertical bearing stiffness of the reinforced foundation during soil compression is 3.25 times the bearing stiffness of an unreinforced foundation.
2. Using the bucket wall as the cathode causes a percolation passage along the bucket wall to form, which decreases the reinforcement effect. The strengthening effect of the conversion electrode method was weaker than using the bucket wall as the anode. In addition, increased internal vertical drainage channel during the reinforcement can effectively improve vacuum pressure transmission inside the soil, thereby improving the reinforcement.
3. The horizontal and vertical bearing capacity of bucket foundation can be significantly increased through vacuum electroosmosis reinforcement. General shear failure of the bucket foundation occurs under vertical load. The vertical bearing stiffness of the reinforced foundation during soil compression is 3.25 times the bearing stiffness of an unreinforced foundation, and the vertical bearing capacity of the foundation increased by 2.1 times after soil reinforcement.
4. The bucket foundation undergoes forward destructive failure when subjected to horizontal load. In the elastic stage, the horizontal resistance of the reinforced foundation is 8.3 times that of the unreinforced foundation, and the horizontal bearing capacity increased by 2.9 times. Soil reinforcement improves the stiffness of the soil and the passive earth pressure; thus, the height of the rotation center is significantly reduced after soil reinforcement.  
Conceptualization, H.D. and P.Z.; methodology, H.D., P.Z. and H.Z.; validation, P.Z. and H.Z.; formal analysis, H.Z. and P.Z.; data curation, C.L. and P.Z.; writing--original draft preparation, H.Z.; writing--review and editing, P.Z., H.Z. and C.L.; funding acquisition, H.D., P.Z. and C.L.  
This research was supported by the National Natural Science Foundation of China (No. 51779171, No.51679163), Innovation Method Fund of China (No. 2016 IM030100), Tianjin Municipal Natural Science Foundation (No. 17)CYBJC22000).  
The authors declare no conflict of interest.