# Model Tests of Soil Reinforcement Inside the Bucket Foundation with Vacuum Electroosmosis Method
## 3 Results and Discussion  
### Effects of Foundation Settlement and Displacement during Soil Improvement  
Figure 8 illustrates the relationship between bucket settlement and water discharge with time during the reinforcement tests. Table 3 shows the foundation settlement and drainage quality under different working conditions. In T1, T2, T3, T5, and T6, water discharge rate decreases with increasing reinforcement time. In T4, the water in the soil is collected using electroosmosis. After the soil is strengthened for approximately 12 h, percolation channels are formed on both sides of the tube wall, and the pumping volume increases rapidly. After 12 h of foundation reinforcement, the foundation  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Test Nos.**} & \multicolumn{1}{c}{\begin{tabular}{c} **Vacuum** \\ **Loading (kPa)** \\ \end{tabular} } & \multirow{2}{*}{**Voltage (V)**} & \multicolumn{1}{c}{\begin{tabular}{c} **Reinforcement** \\ **Time (h)** \\ \end{tabular} } & \multicolumn{1}{c}{\
\begin{tabular}{c} **Bucket Wall** \\ **Electrode** \\ \end{tabular} } & \multicolumn{1}{c}{
\begin{tabular}{c} **Copper Rod** \\ **Electrode** \\ \end{tabular} } \\ \hline T1 & 60 & 0 & 70 & & No \\ T2 & 60 & 0 & 70 & Yes \\ T3 & 60 & 3.75 & 70 & Anode & Yes \\ T4 & 60 & 3.75 & 27 & Cathode & Yes \\ T5 & 60 & 3.75 & 70 & A \(\leftrightarrow\) C \({}^{*}\) & Yes \\ T6 & 60 & 20 & 70 & Anode & Yes \\ TV1 & — & — & — & — \\ TH1 & — & — & — & — \\ TV2 & 60 & 20 & 70 & Anode & Yes \\ TH2 & 60 & 20 & 70 & Anode & Yes \\ \hline \hline \end{tabular} \({}^{*}\) A \(\leftrightarrow\) C means electrode exchange during the test.  
\end{table}
Table 2: Test conditions.  
Figure 7: Installation of bucket foundation: (**a**) Self-weight installation; (**b**) Suction installation.  
reached a maximum settlement displacement of 20 mm. The through-flow passage was created due to the contact surface between the bucket wall and the internal and external soils. The pumping amount subsequently increased linearly with the reinforcement time, and the water discharge weight reached 15 kg at 25 h. The test was stopped after 27 h of operation. Based on the cumulative pumping volume of the first 2.5 h of reinforcement, the drainage quality of T4 reached a maximum of 0.924 kg, and the foundation settlement was 13.599 mm. This is primarily due to the larger surface area of the bucket wall enhancing the electro-osmotic effect compared to the copper tube anode. The moisture content of the soil inside the bucket foundation is large in the initial stage of reinforcement; hence, the reinforcement effect in T4 is best in the initial stage of reinforcement. The reinforcement effect in T1 is the weakest, with a drainage quality and foundation settlement of only 0.388 kg and 2.942 mm, respectively. After 10 h, the reinforcement effect in T6 is the best. Also, the maximum drainage quality in T6 is 1.411 kg, and the maximum settlement of foundation is 20.740 mm, which is primarily due to the large driving voltage. When reinforcement time reaches 50 h, the drainage quality in T6 reaches 5.646 kg, and the foundation settlement is up to 31.412 mm. The foundation settlement in T6 is 1.79 times that in T3, and the weight of water discharge in T6 is 1.80 times that in T3. Therefore, during vacuum piezoelectric infiltration strengthening of the bucket foundation, increasing the electro-osmotic voltage can effectively improve soil consolidation. Furthermore, the T3 foundation settlement is 1.67 times and 1.49 times that in T1 and T2, respectively, and the drainage quality is 1.76 times and 1.53 times that in T1 and T2, respectively. Test results show that the vacuum combined with electroosmosis reinforcement can effectively improve the consolidation rate of the soil inside the foundation compared to the vacuum only preloading method.  
Figure 8: Foundation settlement and water discharge versus reinforcement time: (**a**) Test T1; (**b**) Test T2; (**c**) Test T3; (**d**) Test T4; (**e**) Test T5; (**f**) Test T6.