## 3 Results and Discussion
### Slope Application of Nonwoven Coir Geotextile Simulated Using Roccience--Slide2 Program  
The Slide2 program of Roccience was used in this study to evaluate the performance of geotextiles used as soil reinforcement to stabilize slopes. The performance of the geotextiles was assessed according to the resulting safety factor when the material type and on-center spacing were altered. The primary objective of the analysis was to evaluate the performance of the coir geotextiles compared to commercially available synthetic geotextiles. The application of the Slide2 software program enabled the determination of whether coir geotextiles are a viable alternative to synthetic geotextiles. The slope geometry and soil properties used in the simulation are stated in Section 2.4. The analysis was first performed for the slope without reinforcement, and an initial factor of safety of 1.307 was attained with [PERSON]'s simplified procedure. This factor of safety can be said to be stable for a slope but not for an embankment; therefore, additional support for the ground is required to achieve a factor of safety of 1.5, which was deemed safe for dams [44]. A target value of 1.5 for the safety factor was considered so that the designed slope reaches a satisfactory safety value for most sloped structures. To properly assess the performance of the coir geotextiles, two types of analysis were applied. The first set of simulations was performed under the same conditions as the commercially available synthetic geotextiles. The constant value of spacing was obtained through a repetitive simulation using different spacing values until a factor of safety of 1.5 was obtained for the slope reinforced with synthetic geotextile. The spacing obtained from repetitive simulations to achieve a factor of safety of 1.5 for the slope reinforced with synthetic geotextile was set as constant and used throughout the simulations for all nonwoven coir geotextile samples. With a constant spacing applied in the simulations, the factor of safety values of each coir geotextile sample was assessed. Table 6 shows the resulting factor of safety of the coir geotextiles when using the spacing obtained from the synthetic geotextile to achieve a 1.5 factor of safety. The lengths of all the geotextiles used were set at a constant value of ten (10) meters. The nonwoven coir geotextiles were set at a constant thickness of three (3) millimeters. The allowable tensile strength was obtained from the grab-breaking strength test after the application of reduction factors. The thickness of the synthetic geotextile was 0.9 mm which has a strength nearest to the strength of the natural geotextile As demonstrated by the results, the mercerized coir geotextile subjected to groundwater exposure had the highest factor of safety. In comparing the safety factor of the strongest coir geotextile to that of the synthetic geotextile, it can be observed that with the same spacing, the safety factor showed a decrease of around 4.53% but still showed an improvement as compared to the unreinforced slope. This indicates that with a proper treatment method, the strength of coir geotextiles can increase and improve the stability of slopes with an effect almost comparable with that of synthetic geotextiles. Various analytical methods to calculate the safety factor result in different values. Figure 14 shows the trends of the factor of safety determined according to [PERSON]'s simplified method, [PERSON]'s simplified method, [PERSON]'s method, and the Morgenstern-Price method. In all methods of calculating the factor of safety, a similar trend can be observed in all types of geotextiles: the strongest coir geotextile is the mercerized coir geotextile subjected to groundwater exposure. The second set of simulations was performed to achieve a targeted safety factor by varying the spacing of the coir geotextiles until a safety factor of 1.5 was achieved. Table 7 presents the spacing and the number of geotextiles required for each specimen to achieve the targeted safety factor.