## 5 Results and Discussion
### Box Model Test Results
#### 5.3.3 Vertical Displacements at the Surface of Soil  
Figure 20 shows the surface deformations (soil heave and soil depression) in relation to the specific settlement of the loading plate obtained from the measuring apparatus installed at the surface of model cases (see Figure 9). The results showed that, at 0.05, 0.10 and 0.15\(B\) (of the loading plate), the bearing capacity of each case differed in magnitude. This was because each case had different material properties and different unit weights. The surface deformations around the loading plate were greatly visible, wherein the deeper penetration of the loading plate induced higher vertical displacements at the surface. In Figure 20a, the differences in surface deformation among model cases were not so visible. Case 4 showed the highest soil heaves of 6 and 4 mm at distances of 1000 and 500 mm, respectively. Case 3 showed 3.7 and 5 mm soil leaves at distances of 1000 and 500 mm, respectively. Case 1 showed about 3 and 2.5 mm soil heaves at distances of 1000 and 500 mm, respectively. Case 2 showed soil depressions of 2 and 1.5 mm at distances of 550 and 950 mm. Case 4 obtained the maximum bearing capacity of 79 kPa at 0.05\(B\), followed by Case 2 with 50 kPa bearing capacity. In Figure 20b, the differences in surface deformation among model cases are quite visible. Here, Case 4 showed the highest soil heaves of 16.5 and 13.6 mm at distances of 1000 and 500 mm, respectively. Case 3 showed 11.7 and 10.3 mm soil heaves at distances of 1100 and 500 mm, respectively. Case 1 showed approximately 5.6 and 4.7 mm soil heaves at distances of 1000 and 500 mm. Case 2 showed soil heaves of 2 mm at distances of 400 and 1100 mm. Case 4 obtained the maximum bearing capacity of 135 kPa at 0.10\(B\), followed by Case 2 with 86 kPa bearing capacity. In Figure 20c, more visible differences in surface deformation among model cases can be observed. Here, Case 4 showed the highest soil heave of 25.4 mm and 23.3 mm at distances of 1000 mm and 500 mm, respectively. Case 3 showed 17.6 mm and 19.3 mm soil heaves at distances of 1100 mm and 500 mm, respectively. Case 1 showed about 8.2 mm and 7 mm soil heaves at distances of 1100 mm and 400-500 mm. Case 2 showed soil heaves of 4.4 mm and 4 mm at distances of 1100 mm and 400 mm. Case 4 obtained the maximum bearing capacity of 169 kPa at 0.15\(B\), followed by Case 2, with 121 kPa bearing capacity. Figure 20: _Cont._  
Generally, the results indicated that the maximum vertical displacement at the surface was located 250 mm from the center of the loading plate. As the loading plate penetrated deeper into the soil, at the same time as the applied load increased, the vertical displacement at the surface of the perimeter of the loading plate dilated or bulged (soil heave). This indicated that bearing capacity failure had developed, which was visible at the edges of the loading plate and at the surface [6; 25; 26]. Here, Case 4 showed the highest soil heave of 25.4 mm (see Figure 21d) followed by Case 3 (see Figure 21c). Both reinforced NMC clays (Case 3 and Case 4) exhibited high strengths of bearing capacity, which resulted in General Shear failure mode and were consistent with the load-settlement curves. General Shear failure is the most common type of shear failure which generally occurs in strong soils and can be characterized by a visible soil heave or bulging at the sheared surface. Moreover, the dense sand (Case 2) and the unreinforced NMC clay (Case 1) exhibited Local Shear and Punching Shear modes of bearing capacity failure, respectively. The unreinforced NMC clay (Case 1) showed a clean cut or shear in the surface and a negligible soil heave around the perimeter of the loading plate which characterized a Punching Shear failure (see Figure 21a). The dense sand (Case 2) was expected to exhibit a higher soil heave because of its higher density.