## 3 Results and Discussion
### Microstructure Analysis  
#### 3.3.1 Transverse Relaxation Time \(T_{2}\) Distribution  
Figure 10 illustrates that the NMR transverse relaxation time \(T_{2}\) distribution of the soil-based CLSM showed a distinct bimodal distribution under varying cement contents and initial water contents. The left main peak exhibited a significantly larger signal amplitude per unit mass sample compared to the right secondary peak. The \(T_{2}\) distribution curves of the cemented tailings backfill also exhibited a main relaxation peak and a secondary relaxation peak [49]. This \(T_{2}\) distribution is indicative of water distribution within the pores of the soil-based CLSM sample. In Figure 10a, the \(T_{2}\) distribution curves shifted to smaller transverse relaxation time values with an increase in the cement content, accompanied by a notable decrease in the signal amplitude per unit mass sample corresponding to the main peak. As the cement content increased, the secondary peak also showed a similar trend to the main peak. The signal amplitude represents the amount of water signal at the corresponding transverse relaxation time. Consequently, it can be inferred that the water signal in the soil-based CLSM sample gradually shifted towards a smaller relaxation time with the increasing cement content, accompanied by a decrease in the water signal. Apart from variations in the signal amplitudes of the main peak, the distribution range of the main peak in the water distribution curve of the soil-based CLSM without PCE remained consistent with that of the soil-based CLSM with PCE. As a result of the compaction during the preparation of the T1 samples, the distribution range of the secondary peak decreased. As can be seen in Figure 10b, the \(T_{2}\) distribution curves gradually shifted to larger transverse relaxation time values with the increasing initial water content. The signal amplitude per unit mass sample corresponding to the main peak exhibited a significant increase, indicating a higher water content in the sample. Concurrently, the \(T_{2}\) distribution corresponding to the secondary peak had a wider distribution range with the increasing initial water content. The main peak of the \(T_{2}\) distribution curve in the soil-based CLSM was predominantly concentrated in the range of 0.01-5 ms for different cement contents and in the range of 0.05-9.0 ms for different initial water contents.  
The \(T_{2}\) value corresponding to the main peak in the NMR \(T_{2}\) distribution is denoted as \(T_{\text{2 peak}}\). Figure 11 shows the variation pattern of \(T_{\text{2 peak}}\) under different cement contents and initial water contents. \(T_{\text{2 peak}}\) exhibited a notable rise with a higher initial water content and  
Figure 10: \(T_{2}\) distribution under different (**a**) cement contents and (**b**) initial water contents. Notes: a.u. represent arbitrary units.  
a slight decline with an increasing cement content. At a cement content of 8%, the \(T_{\rm 2 peak}\) for the soil-based CLSM without PCE (T1) measured 1.18 ms, marginally lower than that of the soil-based CLSM with PCE (T2, 1.20 ms), indicating that the inclusion of PCE had a minimal impact on \(T_{\rm 2 peak}\). \(T_{\rm 2 peak}\) represents the most probable aperture of the sample. Therefore, the most probable aperture in the soil-based CLSM decreased with a higher cement content and increased with an increasing initial water content.