## 4 Geotechnical Investigation
Figure 9a shows that for the foundation, at the maximum vertical height of 9.1 mm, the maximum shear displacements are 0.37 mm, 0.72 mm, and 0.64 mm at 104 kPa, 212 kPa, and 300 kPa, respectively. It is shown in Figure 9b that for the three soil specimens from the new road the shear stress attains a peak value of approximately 217 kPa at a normal stress of 300 kPa. With a further increase in normal stress, the shear stress is constant. In contrast, the shear stress attains peak values of 93 kPa and 164 kPa at normal stresses of 104 kPa and 212 kPa, respectively. The maximum stress increases by 57% when the normal stress is increased \begin{table}
\begin{tabular}{c c c c c c} \hline
**Chainage (Km)** & **Location** & **Specific Gravity** & **Bulk Density (g/cc)** & **Void Ratio** & **Bearing Capacity (kPa)** \\ \hline
16+200 & Foundation & 2.54 & 2.14 & 0.43 & 346.42 \\
38+000 & New road & 2.47 & 2.06 & 0.44 & 112.61 \\
38+000 & Old road & 2.53 & 2.21 & 0.39 & 342.13 \\ \hline \end{tabular}
\end{table} 
Table 1: Soil testing results. \begin{table}
\begin{tabular}{c c c c c} \hline
**Pit No.** & **Chainage (Km)** & **Location** & **Direction** & **Moisture Content (\%)** \\ \hline
1 & 9+000 & Foundation & Right side & 17.00 \\
2 & 16+200 & Foundation & Left side & 18.00 \\
3 & 23+050 & Foundation & Right side & 17.00 \\
4 & 28+200 & Foundation & Left side & 16.40 \\
5 & 34+000 & Foundation & Right side & 18.00 \\
6 & 38+000 & Foundation & Right side & 18.00 \\
7 & 38+000 & Foundation & Left side & 18.80 \\
8 & 38+000 & New Road & Right side & 16.00 \\
9 & 38+000 & New Road & Left side & 18.30 \\
10 & 38+000 & Old Road & Right and left sides & 18.00 \\ \hline \end{tabular}
\end{table} 
Table 2: Soil moisture content. from 104 kPa to 300 kPa. Figure 9b shows that for a new road at 104 kPa the vertical height is 0.063 at a shear displacement of 2.7 mm. After that, the vertical height is constant. Figure 9b shows that for a new road at 212 kPa normal stress, 0.69 mm is the vertical height and the shear displacement is 8.5 mm. The trend in the curve shows that the vertical height is directly proportional to the shear displacement. Figure 9b shows that for a new road at 300 kPa normal stress, 0.525 mm is the vertical height at a shear displacement of 6.9 mm. After 6.9 mm, the vertical height is constant. Figure 9: Shear test results at 300 kPa, 104 kPa, and 212 kPa. (**a**) Foundation. (**b**) New road. (**c**) Old road. It is shown in Figure 9c that for the three soil specimens from the old road the shear stress attains a peak value of approximately 119 kPa at a normal stress of 300 kPa. With further increases in the normal stress the shear stress is constant. In contrast, the shear stress attains peak values of 56 kPa and 122 kPa at normal stresses of 104 kPa and 212 kPa, respectively. The maximum stress increases by 70% when the normal stress is increased from 104 kPa to 300 kPa. Figure 9c shows the old road at 104 kPa normal stress, with 0.49 mm as the vertical height at a shear displacement of 9.1 mm. The trend in the curve shows that the vertical height is directly proportional to the shear displacement. Figure 9c shows that for the old road at 212 kPa normal stress, 0.63 mm is the vertical height and the shear displacement is 9.1 mm. The trend in the curve shows that the vertical height is directly proportional to the shear displacement. Figure 9c shows that for the old road at 300 kPa normal stress, 0.56 is the vertical height and the shear displacement is 9.1 mm. The trend in the curve shows that the vertical height is directly proportional to the shear displacement. The shear strength is a linear function of the normal stress. Figure 10 shows the shear stress and normal stress values of the foundation, as well as the old and new subgrade specimens. Figure 10 shows that the angles of internal friction of the foundation and old road specimens are similar. The cohesion of the foundation and the new road is 20 kPa and 25 kPa, respectively. However, cohesion for the old road is zero, and its friction angle is 28.8 degrees.