## 5 Analysis of Test Results of Triaxial Test  
Cement-modified loess displays characteristics of an elastic-plastic material. It exhibits varying strengths, resulting in distinct stress-strain relationships. Initially, during the early stages of specimen loading, the stress-strain relationship approximately forms a linear pattern, adhering to [PERSON]'s law. However, as the applied stress increases and surpasses a certain threshold, the stress-strain relationship deviates from a linear correlation. At this point, a minor increment in stress yields a more substantial increase in strain. Figure 13 illustrates the impact of different cement admixture ratios on the shear strength of cement-modified loess. When compared to loess without cement, the shear strength and shear strength parameters, denoted as c and \(\varphi\), exhibit an initial increase followed by a subsequent decrease. This pattern is attributed to the fact that the strength of loess primarily relies on its inherent characteristics and particle structure. Loess is categorised as a semi-plastic soil with minimal cohesion and an internal friction angle. \begin{table}
\begin{tabular}{c c} \hline \hline
**Name** & **Parameter** \\ \hline Specific gravity & 2.72 \\ Natural density & 1.64 g/cm\({}^{3}\) \\ Dry density & 1.40 g/cm\({}^{3}\) \\ Saturation density & 1.92 g/cm\({}^{3}\) \\ Natural moisture content & 17.54\% \\ Liquid limit & 29.53\% \\ Plastic limit & 17.42\% \\ Plasticity index & 1193 \\ \hline \end{tabular}
\end{table} 
Table 2: Physical properties table of undisturbed loess. Figure 12: TSZ-3 strain-controlled triaxial gauge. The introduction of cement serves to enhance soil cohesion and elevate shear strength. However, when the cement incorporation ratio is low, the amount of cement added to the loess remains relatively small, limiting its ability to reinforce the loess. Additionally, under these conditions, cement particles within the loess may not be uniformly dispersed and well integrated with the loess particles. Consequently, the strengthening effect of cement may not be pronounced, and the shear strength of the loess remains relatively low. As the cement admixture ratio increases, the hard-setting skeleton formed through cement hydration becomes more effective, enabling higher peak strength to be achieved in cement-modified loess. From Figures 14 and 15, it can be seen that the shear strength parameters c and \(\varphi\) increase with the increase in the cement admixture in cement-modified loess. The cohesive strength c of cement-modified loess increased more when the cement dosing ratio was increased from 3% to 5%. The internal friction angle \(\varphi\) of cement-modified loess increased more when the cement mixing ratio was increased from 5% to 7%. In cases where the cement mixing ratio is less than 5%, insufficient hydration and hydrolysis reactions occur, failing to establish a continuous hardened skeleton. Consequently, the strength of cement-modified loess primarily hinges on the plasticity of the enhanced soil particles, resulting in less-pronounced strength improvement. As a result, when compared to cement-modified loess with a higher cement mixing ratio, cement-modified loess with a lower cement mixing ratio exhibits lower strength after the cement has hardened. Nevertheless, it is essential to consider that, in practical projects, there is a diminishing return on both cost-effectiveness and utilisation when the cement admixture surpasses a certain threshold. Therefore, the optimal cement admixture ratio for cement-modified loess should be determined through appropriate testing. Figure 16 displays the stress-strain curves of cement-modified loess subjected to varying enclosure pressures. The peak strength is not only associated with the cement dosage, but is also dependent on the magnitude of the surrounding pressure. The peak shear strength of the cement-modified loess specimens increases with higher peripheral pressure.