## 3 Numerical Analysis Results and Discussion under Static Loading
### Lateral Displacements at Wall Facing
#### 3.1.1 Effects of Wall Facing Type and Construction on Lateral Displacements at Wall Facing  
In this study, the results show that the _dx_ behaviors at the wall facing in each model are very distinct from each other. The differences may be attributed to the effects of having a different wall facing material, design, and construction method. Hence, Case 1A-C (GRS-IB) models showed the least _dx_ at the wall facing compared to those of Case 2A-C (GRS-IB) and Case 3A-C (IB) models (see Figure 7). This is because the GRS-IB technology allows the _dx_ at the wall facing to occur during the construction. Afterwards, the GRS wall facing _dx_ during the construction had been eliminated when the FHR facing was constructed. The negligible _dx_ at the wall facing is due to the post-construction surcharge loads. This is one of the advantages of this technology wherein compaction can be applied thoroughly but cautiously on the backfill, especially near the wall facing, without too much concern for wall facing damage or excessive deformation. Moreover, the FHR facing of the GRS-IB model carries the loads from the reinforced concrete (RC) girder, hence, the GRS abutment carries the minimal surcharge loads. It can be observed that the _dx_ behavior of the FHR facing did not bulge but was rather almost straight from the base towards the top of the wall. This may be because the FHR facing of the GRS-IB is 0.90 m thick and has very high stiffness. Thus, the _dx_ at the wall facing of GRS-IB (Case 1A-C) models after  
Figure 7: Lateral displacements at the wall facing, _dx_ (mm), when models are subjected to different static loadings: Case 1A, 2A, 3A (end of bridge construction); Case 1B, 2B, 3B (applied general traffic loading); and Case 1C, 2C, 3C (applied railway loading). the bridge construction and load application is very minimal, with a maximum range of 0.002-0.02% (_dx/H_) at the top of the wall facing. In contrast, Case 2A-C (GRS-IBS) showed the highest _dx_ at the wall facing compared to Case 1A-C (GRS-IB) and Case 3A-C (IB) models (see Figure 7). The _dx_ at the wall facing in the GRS-IBS models after the bridge construction and load application is greater than those in the GRS-IB and IB models, with a maximum range of 0.18-0.27% (_dx/H_) at the top of the wall facing. This occurred because the GRS-IBS models have 0.50 m-thick concrete masonry blocks as the wall facing material, whereas the GRS-IB and IB models have 0.90 m-thick FHR facing. The GRS wall is a flexible structure and the wall facing is weak at the block-to-block joint connection. Thus, an outward movement of the block facing is expected to occur during the construction due to the lateral earth pressure from the backfill soil. In addition to that, the bridge surcharge loads are directly applied on the bridge seat at the top of the abutment and are supported by the geosynthetic-reinforced bearing zone. Hence, the greater _dx_ at the wall facing occurred as a result of the increase in lateral earth pressures due to the additional bridge surcharge loads. Moreover, the deformation of the reinforced soil foundation (RSF) may have attributed also to the magnitude of the _dx_ at the wall facing. The last case models, Case 3A-C, exhibited similar _dx_ behavior at the wall facing compared to Case 1A-C (GRS-IB) models but slightly greater (see Figure 7). The differences between the two bridge designs are that the IB models have no reinforcements in the backfill and have a wider RC footing that extends behind the wall facing. In this case, the construction and type of wall facing influenced the behavior of its _dx_. During construction, the IB FHR facing and RC footing were activated first before the backfill lifts had been placed. When the IB FHR facing and RC footing were constructed above the reinforced soil foundation (RSF), the RSF exhibited more displacements at the toe than at the heel, probably due to the distribution of the IB dead loads. At the end of the bridge construction, it is noticeable that _dx_ at the wall facing is very minimal.