## 2 Materials and Methods
### Testing Procedures  
Geocells are typically subjected to gravity loads from the infill materials on steep slopes [22]. The force diagram of the geocell on the slope is shown in Figure 4. The geocell junctions have the critical features that support and transfer the load. The geocells are affected by the filling materials in all directions, resulting in four forms of failure at the junctions:  
1. By local overstressing, the fixation element locally overstresses the junction (in the same way as a tensile test on a welded junction);
2. By shear, a force parallel to the junction itself causes failure;
3. By peeling, a force normal to the junction separates the strips from each other at one edge of the junction, causing failure;
4. By splitting, two strips adjacent to the junction are pulled apart by a force normal to the junction. Four types of tensile tests were carried out on the geocell junctions. According to \"Geosynthetics in railway engineering--Part 1: Geocell\" (Q/CR 549.1-2016), the overall length of the sample was 220 mm, the width of the sample was the strip width of the geocell (the height of the geocell), and the clamping distance was 100 mm when the sample was tensioned after the preload was applied. The schematic drawings in Figures 5-8 show the detailed configuration and loading scenario. Combined with the standards and relevant \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Connection Mode of** & **Strip Material** & **Height of the** & **Distance of the** \\
**the Junctions** & **Geocell (mm)** & **Junction (mm)** \\ \hline Ultrasonic welding & HDPE & 100 & 280 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Specifications of the geocell. Figure 4: Schematic diagram of local stress. Figure 3: Details of the geocell junction. (unit: mm). scholars' research, the distances between clamps of 10.5 mm, 25 mm, 50 mm, and 100 mm were utilized in the experiments to explore the effect of clamping distance on different types of junction tensile testing. These distances ensure that no pre-load is applied to the specimen before the actual test begins. The specimens used in all the tests were initially cut to the correct size for the tensile test. It should be mentioned that stretching with a clamping distance of 10.5 mm was difficult due to the method of the splitting and peeling strength tests, as well as material considerations. Additional samples were tested as necessary to facilitate a high level of consistency. The detailed specimen sizes for the junction test are summarized in Table 2. The types of geocell junction tests include the weld tensile strength, tensile shear, peeling, and splitting tests. This study is intended to supplement and unify test standards as well as to provide a test scheme and data support. There can be a test basis when the geocell specification cannot be tested according to existing standards and the clamping distance needs to be increased or reduced. Figure 5: Weld tensile strength tests under different clamping distances: (**a**) 10.5 mm, (**b**) 25 mm, (**c**) 50 mm, (**d**) 100 mm. Figure 6: Tensile shear tests under different clamping distances: (**a**) 10.5 mm, (**b**) 25 mm, (**c**) 50 mm, (**d**) 100 mm. Figure 8: Splitting tests under different clamping distances: (**a**) 25 mm, (**b**) 50 mm, (**c**) 100 mm. Figure 7: Peeling tests under different clamping distances: (**a**) 25 mm, (**b**) 50 mm, (**c**) 100 mm. All the test methods were designed in reference to \"Geotextiles and geotextile-related products--Strength of internal structural junctions--Part 1: Geocells\" (ISO 13426-1-2019), and all the tests were performed on an X-shaped sample cut from the geocell panel (Figure 4; red surrounding area). 1. Method A--Weld tensile strength test (Figure 5d)  
The legs A and C of the \"X\" are fixed in the in the upper clamp, and the legs B and D are similarly fixed in the bottom clamp. The sample is tested at a constant tensile rate by adjusting the clamping distance until the junction is plasticized and damaged. 2.