## 3 Stress Analysis of the Most Unfavorable Layer of Cement-Stabilized Base during Construction
### Vehicle Load Analysis during Road Construction  
The pavement structure of the 203 Highway in the Inner Mongolia Autonomous Region of China is 4 cm AC-13 fine-grained asphalt concrete (upper pavement layer) + 6 cm AC-20 medium-grained asphalt concrete (lower pavement layer) + 18 cm 5% cement-stabilized macadam (base) + 32 cm 4.5% cement-stabilized macadam (subbase). The design speed is 80 km/h, and the width of integral subgrade is 26.5 m. The width of the subgrade is divided into (0.75 m on the left shoulder + 2.5 m on the left shoulder + 2.75 m on the left shoulder + 2 \(\times\) 3.75 m on the lane + 0.5 m on the left edge) \(\times\) 2 + 4.0 m on the central dividing bandwidth, and the length of the road is 30 km. An investigation of vehicle loading during the construction period showed that the minimum axle load is 100 kN, the maximum axle load is 235 kN, and the axle load mainly concentrates between 120 kN and 180 kN, far exceeding the standard axle load in the design code [29]. In order to analyze the influence of heavy haul trucks on early road construction, the following empirical relationship between Belgian grounding area and axle load is adopted:  
\[A=(0.008P+152)\pm 70. \tag{8}\]  
In the equation, \(A\) is the area of a single wheel tire in cm\({}^{2}\), \(P\) is the load of a single wheel tire \(N\), and \(\pm\) 70 means the margin of guarantee reaches 90%. The calculated ground area of vehicles under different axle loads is shown in Table 3. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Compactness (\%)**} & \multicolumn{2}{c}{**7d Compressive**} & \multicolumn{2}{c}{**7d Compressive**} & \multicolumn{2}{c}{**7d Compressive**} \\  & **Strength Sensitivity** & **Water Content** (\%)** & **Strength Sensitivity** & **Temperature** (\({}^{\circ}\)**C)** & **Strength Sensitivity** \\  & **Factor** & **(\%)** & **Factor** & **(\({}^{\circ}\)**C)** & **Factor** \\ \hline
96 & / & 4.9 & / & 10 & / \\
98 & 0.19 & 5.9 & 0.94 & 15 & 0.104 \\
100 & 0.215 & 6.9 & 0.51 & 20 & 0.108 \\
102 & 0.295 & 7.9 & 0.04 & 25 & 0.05 \\ / & / & / & / & 30 & 0.044 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Sensitivity factors for various factors. In order to analyze the damage caused by different axle loads to the road surface, this paper assumes that the same axle load has the same load. According to the length and structure of the road section, the total mass of the mixture needed for paving the road section was calculated. The load of different axle loads was different, and the total mass divided by the load could get the number of vehicles for different axle loads. The calculation results are shown in Table 4, the frequency of loading trucks. The closer to the mixing station, the more times the mixing station was subjected to the full load (Figure 6). It is necessary to convert the number of vehicle loads during construction into standard axle loads. Following regulations and research from relevant scholars [30], this paper adopts the principle of equivalence of tensile stress for the semirigid material layer. Results are shown in Table 5. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Axle Load (kN)** & **Subbase** & **Base** & **Lower Pavement Layer** & **Upper Pavement Layer** & **Total** \\ \hline
100 & 14,400 & 7200 & 3038 & 2025 & 26,663 \\
130 & 8450 & 4225 & 1782 & 1188 & 15,645 \\
160 & 6000 & 3000 & 1266 & 844 & 11,110 \\
190 & 4639 & 2319 & 979 & 652 & 8589 \\
220 & 3781 & 1891 & 798 & 532 & 7002 \\
250 & 3200 & 1600 & 675 & 450 & 5925 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Frequency of loading trucks. Figure 6: Distribution of load times. Red indicates that the number of vehicles under full load is high, whereas the yellow indicates the number of vehicles under full load is low.