## 3 Experimental Results and Analysis
### One-Dimensional Compression Tests  
For the one-dimensional compression characteristics test, a GDS one-dimensional consolidation apparatus is used. Axial pressure is applied by injecting water into the axial pressure bladder via an axial pressure volume controller, which also monitors the axial pressure in real time. The back pressure controller and base pressure controller simultaneously control and measure the water pressure at the top and bottom of the sample. Using a top displacement sensor and full computer control, the system can achieve constant stress loading and high-precision monitoring. Table 1 summarizes the loading scheme used in the compression test.  
One-dimensional compression tests were performed on the MICP-treated soil. The loading scheme is shown in Table 1. As the load gradually increases, the deformation of the untreated soil samples is more pronounced compared to the MICP-treated soil. Therefore, MICP treatment significantly improves the compression properties of soil under large external loads.  
As shown in Figure 5, the compression coefficient of the MICP-treated soil decreased notably. We selected a linear section of the \(e\)-lg \(p\) curve to calculate the compression index of the soil before treatment (\(C_{c}=0.225\)) and after 14 days of treatment (\(C_{c}=0.172\)). These results are similar to the findings of [PERSON]'s research on _Sporosarcina-pasteurii-_induced carbonate precipitation in organic soil [16]. Both studies indicate that bacterial treatment effectively improves the compression performance of the soil.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**No.** & **Period (Day)** & **Axial Stress (kPa)** \\ \hline
1 & 0 & 25\(\rightarrow\)50\(\rightarrow\)100\(\rightarrow\)200\(\rightarrow\)50\(\rightarrow\)100\(\rightarrow\)200\(\rightarrow\)400\(\rightarrow\)800\(\rightarrow\)1600 \\
2 & 14 & 25\(\rightarrow\)50\(\rightarrow\)100\(\rightarrow\)200\(\rightarrow\)100\(\rightarrow\)50\(\rightarrow\)100\(\rightarrow\)200\(\rightarrow\)400\(\rightarrow\)800\(\rightarrow\)1600 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Loading scheme for one-dimensional compression test.  
Figure 4: Decrease curve of permeability coefficient with periods.  
We also performed unloading-reloading tests and obtained the relationship curve between the pore-space ratio and stress under springback-recompression conditions. The results indicate that the recompression index before treatment is Ce = 0.0226, and the recompression index after treatment is Ce = 0.0188. Similar to the compression index, the compression and recompression indexes of the MICP-treated soil are lower than those of the soil before treatment. Consequently, MICP treatment effectively decreases the compression index of soft clay and improves its overall compression performance.  
According to the strain-time relationship of the soil under loading, we can calculate the consolidation coefficient of the soil under each loading condition. [PERSON] et al. [31] proposed that the time square root method is the best approach when the loading ratio is larger than 5 and the loading time is limited. As shown in Figure 6, as the load increases, the consolidation coefficient of the soil consistently increases. However, the consolidation coefficient of the soil after treatment is lower than that of the soil before treatment. Consequently, the soil after MICP treatment takes a longer time to complete consolidation.  
Figure 5: \(e\)-lg \(p\) curve of one-dimensional compression test.  
Figure 6: Soil consolidation coefficient under different loads.