## 3 Results and Discussion
### Aging Test Results and Electron Microscopy Microscopic Analysis  
Based on the above analysis, the influence of clay content on the experimental values is relatively small, and a clay slurry content of 14.29% is selected as the unified choice for the experimental plan. We developed four different testing plans, namely, a blank group (300 g/m\({}^{2}\), 400 g/m\({}^{2}\), 500 g/m\({}^{2}\)), the most economical group (300 g/m\({}^{2}\) + 1 layer slurry, 300 g/m\({}^{2}\) + 2 layer slurry), the intermediate group (400 g/m\({}^{2}\) + 5 layer slurry), and the safest group (500 g/m\({}^{2}\) + 3 layer slurry). According to Figure 13, after 144 h of fluorescent UV lamp aging testing, the strength retention rates of geotextiles with specifications of 300 g/m\({}^{2}\) and 400 g/m\({}^{2}\) were 69.18% and 77%, respectively, which did not meet the standard qualification requirement of 80%. The strength retention rate of the same specification of sprayed geotextile fabric is significantly higher than 100%, and the strength retention rate can also reach over 100% when the mud  
Figure 12: PPR modeling calculation results. layer is scraped off for testing. This indicates that the spraying method has good protection for geotextiles, and the sand immersed in the fibers can also improve the overall tensile strength to a certain extent. Although the 500 g/m\({}^{2}\) geotextile meets the standard in the aging test, its cost-effectiveness is not outstanding due to cost considerations. The internal fiber structures of three types of geotextiles--aged geotextiles (referred to as L) and slurry-coated geotextiles after aging tests (referred to as J)--were observed using a scanning electron microscope (SEM). Figure 14 presents the SEM images of the L geotextile samples. The images reveal that the fiber structures of the geotextiles with three specifications (300 g/m\({}^{2}\), 400 g/m\({}^{2}\), and 500 g/m\({}^{2}\)) suffered varying degrees of damage under prolonged exposure to ultraviolet (UV) radiation and high temperatures. This damage manifested as multiple fractures in the fibers, including thermal decomposition, melting, and deformation. High temperatures exacerbated the aging effects of UV radiation on the geotextiles, making the fibers more brittle. These observations align closely with the aging state of fibers in geotextiles sampled from the K135 site under natural environmental conditions, further confirming that UV radiation and high temperatures are critical factors in the aging process of geotextiles. Figure 15 shows a scanning electron microscope image of the J geotextile sample. In that figure, it can be seen that after the accelerated aging test, the geotextile fibers treated with spraying showed good durability. There are many fine sand particles attached to the fibers, as well as many small slurry particles. The presence of these fine sand particles and small slurry particles will help improve overall wear and erosion resistance. Whether a process involves spraying one layer, two layers, or three layers, it has a significant protective effect on the geotextile. The presence of the sprayed layer effectively reduces the direct erosion of geotextile fibers by ultraviolet rays and other environmental factors, thereby extending the service life of geotextiles. This observation result is highly similar to the fibrous state of the mud soil bags in the water level zone of the K135 revetment under electron microscopy scanning. Figure 13: Test results of aging test. Figure 14: SEM images of virgin geotextile (sample L) after aging tests: (**a**) specification 300 g/m\({}^{2}\) geotextile; (**b**) specification 400 g/m\({}^{2}\) geotextile; (**c**) specification 500 g/m\({}^{2}\) geotextile. Figure 15: _Cont._  
Figure 16 presents comparative scanning electron microscopy (SEM) images of geoctextiles before and after aging tests, including slurry-coated samples.