## 3 Experimental and Numerical Procedures
### Performance of RSF with Different Reinforcing Techniques  
Figure 12 shows the relationship between the simulated \(q\) and S/B of B20, B60 and B100 with the four configurations (Series C, D, E and F). For all cases, the \(q\) initially increased with the increase of S/B ratio up to a particular S/B\({}_{\rm f}\). When S/B \(>\) S/B\({}_{\rm f}\), the \(q\) value was slightly increased, and it can be assumed as achieving the failure state. For Series C, D and E, the S/B\({}_{\rm f}\) = 12, 8, 6, 5, and 5% for B20, B40, B60, B80 and B100, respectively, for N = 1-4. The \(q\) for Series F was fully developed at the S/B\({}_{\rm f}\) = 14% for N = 1 to 4. It was evident that the development of \(q\) in Series F was the highest when compared with other Series. The development of \(q_{b}\) depended on not only the types of tested soil, but also the reinforcing techniques (planar and wraparound ends), which will be discussed in the next section. Figure 11: Relationship between the soil-reinforcement interface and plasticity index (PI). Figure 13 shows the relationship between \(q_{b}/q_{0}\) versus N for Series C, D, E and F. Figures 14-19 show the simulated results of the total displacement vectors and stress distribution (Sig-yy) of B0, B20 and B100 at the S/B ratio of 15% for Series C, D, E and F with N = 4, respectively. When the unreinforced soil (Series A) was subjected to the vertical applied stresses, the soil particles beneath the footing moved downward to horizontal direction on both sides with large areas, as shown in Figures 14a, 15a and 16a for B0, B20 and B100, respectively. The triangular shaped wedge under the footing was clearly observed, as shown Figures 17a, 18a and 19a for B0, B20 and B100, respectively. When PI \(<\) 30% (B0 and B20), the \(q_{b}/q_{0}\) increased from 1.4 to 2.4 for B0 and 1.24 to 1.76 for B20 due to the increase in N from 1 to 4, as shown in Figure 13 (for Series C). On the other hand, when PI \(>\) 30% (B40, B60, B80 and B100), the \(q_{b}/q_{0}\) development was comparatively low with the additional N. The \(q_{b}/q_{0}\) ratio of B40, B60, B80 and B100 was approximately from 1.03 to 1.22 for N = 1 to 4. These results can be explained by Figures 14b and 15b, in that the amount of horizontal displacement vectors at soil-geotextile interfaces of B0 and B20 densely occurred on all layers of geotextile reinforcement. However, the vectors of B100 mostly occurred only on the first layer while it lightly occurred on other layers, as shown in Figure 16b. In general, the geotextile reinforcement can significantly increase the \(q_{b}\) by its high tensile resistance and the soil-reinforcement interface shear resistance [3; 40]. The soil particles under the footing moved along the geotextile in lateral direction, as shown in Figures 14b, 15b and 16b, while the high interface strength tried to prevent the movement of soil particles and, therefore, improved the \(q_{b}\). Moreover, the applied stress to the soil was lower when compared to unreinforced soil as some stresses were transferred to the geotextile. The deformed reinforcement can support the part of applied stress to the soil by developing upward force, as shown in Figures 17b, 18b and 19b. The full-wraparound ends of geotextile filled with the foundation soil (Series D) can significantly improve the \(q_{b}\) of B0, B20 and B40 (PI \(<\) 118%) with increasing the N layers, as shown in Figure 13. The \(q_{b}/q_{0}\) was improved in a range of 1.77 to 3.30 for B0, 1.45 to 1.90 for B20, and 1.44 to 1.75 for B40 when the N value increased from 2 to 4. Most of the displacement vectors of soils appeared within the full-wraparound geotextile ends, as illustrated in Figures 14c and 15c. When comparing Series D to Series C, the \(q_{b}\) development in Series D was higher than that for Series C for the same foundation soils. Nevertheless, when PI \(>\) 118% (B60, B80 and B100), the \(q_{b}/q_{0}\) was lower than 1.25 for all N values.