**2. Materials and Methods**

*2.1. Material*

2.1.1. Soil

The soil was collected from a site in Gaomiao Village, Chongqing, with dense soil, small porosity, brownish-red soil color, and large water content, but the soil was still in a plastic state. After bringing the soils back to the laboratory, they were placed into an electric constant temperature air blast drying box to dry and left at 100 ◦C for 24 h before all steps. Then, they were crushed and passed through a 1 mm nylon sieve after removing stones, tree roots, and other impurities.

Table 1 shows the basic physical properties of soil taken from the limit moisture content test, and the compaction test, which were carried out according to the Standards for Geotechnical Test Methods (GB/T 50123-2019). The soil was sieved to obtain a coarsegrained group containing more than 25% and not more than 50% and satisfying *wL* < 50%, *IP* ≥ 7, and *IP* ≥ 0.73(*wL* − 20). According to the engineering classification standard of soil (GB/T 50145-2007), the soil is low-liquid-limit clay. The sealed soil was assessed using the XRF to identify the chemical composition and relative content of each composition. The results are shown in Figure 1.


**Table 1.** Basic physical properties of undisturbed soil samples.

**Figure 1.** Main chemical components of undisturbed soil.
