## 3 Results and Discussion  
### Deviator Stress-Strain Curves and Shear Strength Parameters  
The deviator stress-strain curves of silt, silty sand, and mucky silty clay under various stress paths are shown in Figure 5, and the deviator stress at 15% axial strain is summarized in Table 4. Silt and silty sand have comparable shear strength, but mucky silty clay has  
Figure 4: BES software interface display diagram. much lower shear strength due to its high clay particle content. The deviator stress for Group B was less than the deviator stress for Groups A and C. This was mainly because the confining pressure of Group B (60 kPa) was smaller than the confining pressure of Groups A and C (150 kPa). The difference in deviator stress between Groups B and A was much smaller for mucky silty clay, indicating that the influence of confining pressure on the shear properties of mucky silty clay is not readily apparent due to its high void ratio and clay particle content. Under the unloading path, as unloading intensity increased, the deviator stress of the three soils gradually decreased. When the single unloading intensity was 10 kPa (C\(-\)1), the deviator stress curves of silt and silty sand were almost identical to the conventional triaxial curve, indicating that low unloading intensity had little effect on the shear strength of the two soils. For mucky silty clay, although the final deviator stress is nearly identical, the deviator stress under the unloading-reloading path showed characteristics of first increasing and then decreasing. The final deviator stress at 15% axial strain is summarized in Table 4. The normalized deviator stress-unloading intensity curves for Group B and C tests are shown in Figure 6, where Group B used B\(-\)1 as a reference value and Group C used the conventional triaxial A\(-\)0 as a reference value. Increased unloading intensity had the greatest effect on the deviator stress of silt. When unloading intensity was set at 30 kPa, the deviator stress of silt was reduced by 10% under the unloading path, and by 7% under the unloading reloading path. The variation law of the deviator stress of the three soils with unloading intensity is consistent under the unloading-reloading path. When unloading intensity was low, deviator stress reduction was not readily apparent. With increasing unloading intensity, the deviator stress rapidly decreased at first and then slowed down. In practical engineering, although the stress level of the soil is restored following foundation pit excavation and structural construction, close attention should be paid to the effect of the unloading-reloading stress path on the shear strength of the soil. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Stress**} & \multirow{2}{*}{**Soils**} & \multicolumn{8}{c}{**Stress Path**} \\ \cline{3-8}  & & **A\(-\)0** & **B\(-\)1** & **B\(-\)2** & **B\(-\)3** & **C\(-\)1** & **C\(-\)2** & **C\(-\)3** \\ \hline \multirow{3}{*}{(\(\sigma_{1}\)–\(\sigma_{3}\))/ (kPa)} & Silt & 525.35 & 329.14 & 310.63 & 296.5 & 517.47 & 494.22 & 489.18 \\  & Silty sand & 523.08 & 331.06 & 315.86 & 315.45 & 521.34 & 509.74 & 503.64 \\ \cline{1-1}  & Mucky silty clay & 135.84 & 122.74 & 121.80 & 118.12 & 133.93 & 129.04 & 127.80 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Final deviator stress of soil under different stress paths (Unit: kPa). Figure 5: Deviator stress–strain relationship of soil under different stress paths. (**a**) Groups A and C; (**b**) Group B. The shear strength parameters of reconstituted silt, silty sand, and mucky silty clay in various stress paths are shown in Table 5. In comparison to conventional triaxial test, the lateral unloading test significantly reduces the shear strength parameters, including effective cohesion \(c^{\prime}\) and internal friction angle \(\varphi^{\prime}\). Similar tests were carried out using clay of low plasticity, and results showed that \(c^{\prime}\) decreased while \(\varphi^{\prime}\) increased in the unloading path [25].