## 2 Test Overview
### Test Scheme  
Remolded soil samples were used in this test. The screened expansive soil and weathered sand were put into the oven, dried at 105 \({}^{\circ}\)C for 24 h to remove moisture, and then put into the drying oven for cooling and reserving. Taking the quality as the index, according to the dosages of 0%, 10%, 20%, and 30%, respectively, the weathered sand was mixed into the expansive soil and adjusted to the best moisture content. Till the size distribution of clay particles was uniform, the mixture was put in a constant temperature and humidity curing box for 24 h, so that the moisture between clay particles could be fully transferred. The soil sample was compacted into 5 layers using the layered compaction method. At the same time, to avoid the damage caused by the weak surface due to the layering of the specimen, the contact surface of each layer was required to be shaved by a scraper in the compaction process. The final cylindrical specimen with a diameter of 50 mm and a height of 100 mm was made, and the dry density of the expanded soil was 1.73 g/cm\({}^{3}\) at this time. Because of the small permeability coefficient of the expansive soil, the vacuum saturation method was used in the test. After 7 h of air pumping, the specimens were placed in water for 12 h. The specimens were then covered with impermeable plates to prevent water evaporation. As shown in Figure 2, the high- and low-temperature-alternating test chamber was used in the freeze-thaw test to simulate the climate environment of Xinjiang. Taking into \begin{table}
\begin{tabular}{c c c c c c} \hline \(\rho\)1/ & \(W_{1}\)/\% & \(W_{1}\)/\% & \(W_{1}\)/\% & \(W_{p}\)/\% & \(G_{s1}\) & \(F_{s}\)/\% \\ \hline
1.91 & 21.67 & 65 & 36 & 2.69 & 52 \\ \hline \end{tabular}
\end{table} 
Table 1: Basic physical parameters of expansive soil. \begin{table}
\begin{tabular}{c c c c c c} \hline \(\rho\)2/ & \(W_{2}\)/\% & \(C_{u}\) & \(C_{c}\) & \(\gamma\)/ & \(A\) \\ (g/cm\({}^{3}\)) & & & & (kN/m\({}^{3}\)) & & \\ \hline
1.67 & 12.24 & 53.2 & 18.4 & 16.34 & 0.31 \\ \hline \end{tabular}
\end{table} 
Table 2: Basic physical indicators of weathered sand. Figure 1: GDS dynamic triaxial test device. account the average local temperature, \(-20\)\({}^{\circ}\)C was set as the freezing temperature, \(20\)\({}^{\circ}\)C was the melting temperature, the freeze-thaw times of 12 h each, and 24 h was a freeze-thaw cycle. Considering that the lateral deformation of foundation soil is much smaller than the longitudinal deformation when it bears the load in actual engineering, it was approximately considered that there was no lateral deformation the of soil. In the process of freezing and thawing, the soil sample is subjected to lateral constraints through the saturator [17]. Also, to keep the moisture content of the specimens stable during freeze-thaw, it was necessary to wrap the polyethylene film around the specimen to prevent the evaporation of water. According to the relevant studies, the mechanical properties of the soil stabilized after five freeze-thaw cycles [18], so the numbers of freeze-thaws selected for the test were 0, 1, 3, 6, and 9, where the 0 freeze-thaw specimen was unfrozen soil. This dynamic triaxial test was carried out under consolidation without drainage conditions with the consolidation ratio Kc = 1. Considering the average depth of the frozen soil was 1.6 m, the calculated consolidation envelope pressure was selected to be 50 kPa, and the consolidation was considered to meet the specification requirements when the drainage volume was less than 0.1 cm\({}^{3}\) within 1 h. Subsequently, cyclic loading was carried out, and the cyclic load was divided into 8 levels (0.3\(\sigma\)3-1.0\(\sigma\)3) with 10 cycles per level, and the loading method is shown in Figure 3.  
After the completion of each stage, the pore water pressure valve was briefly opened to prevent the influence of the pore water pressure generated by the upper load on the lower level loading.