# Health State Assessment of Road Tunnel Based on Improved Extension Cloud Model
## 4 Case Application
### Process of Tunnel Health Evaluation  
Regular health inspections of the tunnel are carried out every year on the Zhangzhuo Expressway. Then, the health status of the highway tunnel is evaluated according to the current Chine code \"Technical Specification for Highway Tunnel Maintenance\" (JTG H12-2015). The detection data of these years provide data support for verifying the method of this paper. In the paper, the conventional detection data in two directions of the North Longmen Tunnel are selected for evaluation. The index value is the worst-measured value (Table 4). No defects were found in the selected evaluation sample tunnels, including the tunnel portals and holes. Quantitative indicators are measured using actual values, whereas non-quantitative indicators are evaluated based on actual conditions and assigned values accordingly. For example, the degree of leakage C4 can be divided into five categories: no disease, seepage, dripping, flowing, and jetting, with corresponding values of 0.1, 0.3, 0.5, 0.7, and 0.9. The boundary values of each indicator level for the cloud model of the optimized tunnel health grade were determined according to Section 2.3 of the method for health status classification and Section 3.1 for calculation methods, as shown in Table 5. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Indicator**} & \multicolumn{2}{c}{**2014**} & \multicolumn{2}{c}{**2015**} & \multicolumn{2}{c}{**2016**} & \multicolumn{2}{c}{**2017**} & \multicolumn{2}{c}{**2018**} \\ \cline{2-10}  & **Up** & **Down** & **Up** & **Down** & **Up** & **Down** & **Up** & **Down** & **Up** & **Down** \\ \hline C1 & 6 & 7.5 & 6 & 7.5 & 6 & 8 & 8 & 9 & 6 & 9 \\ C2 & 1.5 & 1 & 1 & 3 & 1 & 3 & 1.2 & 3 & 1 & 3 \\ C3 & 0.168 & 0.215 & 0.168 & 0.247 & 0.148 & 0.185 & 0.149 & 0.161 & 0.148 & 0.154 \\ C4 & 0.1 & 0.1 & 0.1 & 0.3 & 0.1 & 0.3 & 0.3 & 0.5 & 0.3 & 0.5 \\ C5 & 0.146 & 0.230 & 0.146 & 0.247 & 0.188 & 0.275 & 0.188 & 0.258 & 0.146 & 0.146 \\ C6 & 0.1 & 0.1 & 0.5 & 0.3 & 0.5 & 0.3 & 0.5 & 0.5 & 0.5 & 0.5 \\ C7 & 0.1 & 0.1 & 0.3 & 0.3 & 0.3 & 0.3 & 0.3 & 0.3 & 0.3 \\ C8 & 90.0 & 83.6 & 90.2 & 80.1 & 87.2 & 76.2 & 84.3 & 66.4 & 81.8 & 62.1 \\ C9 & 0.253 & 0.415 & 0.384 & 0.585 & 0.520 & 0.860 & 0.498 & 0.878 & 0.371 & 0.450 \\ C10 & 89.6 & 89.9 & 91.3 & 90.2 & 90.7 & 89.0 & 90.0 & 88.6 & 89.5 & 88.0 \\ C11 & 0.119 & 0.328 & 0.209 & 0.507 & 0.567 & 0.612 & 0.552 & 0.522 & 0.448 & 0.463 \\ C12 & 62.3 & 87.5 & 61.2 & 86.0 & 50.1 & 78.1 & 50.1 & 76.6 & 49.7 & 75.3 \\ C13 & 0.113 & 0.121 & 0.348 & 0.289 & 0.325 & 0.289 & 0.098 & 0.149 & 0.098 & 0.117 \\ \hline \hline \end{tabular} Note: Up represents upstream, Down represents downstream.  
\end{table} 
Table 4: Indicator values of Beilongmen Tunnel. Figure 4: Beilongmen Tunnel of Zhangzhuo Expressway Baoding section. (**a**) Description of the location of the Beilongmen Tunnel; (**b**) Description of the main entrance of the Beilongmen Tunnel. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{1}{c}{**Indicator**} & **I** & **II** & **III** & **IV** & **V** \\ \hline C1 & (0.5, 0.30, 0.03) & (2, 0.59, 0.059) & (4, 0.59, 0.059) & (7.5, 1.48, 0.148) & (10, 1.48, 0.148) \\ C2 & (0.01, 0.006, 0.001) & (0.51, 0.29, 0.029) & (2, 0.59, 0.059) & (4, 0.59, 0.059) & (5, 0.59, 0.059) \\ C3 & (0.1, 0.06, 0.006) & (0.3, 0.06, 0.006) & (0.5, 0.06, 0.006) & (0.7, 0.06, 0.006) & (0.9, 0.06, 0.006) \\ \hline \hline \end{  
with the standard. After 2015, the tunnel health grade has increased year by year, indicating a deterioration of the health condition, possibly due to factors such as geological environment, material degradation, traffic loads, and temperature changes. This result conforms to the degradation law of tunnels over time [38]. A health warning was issued for the downstream channel in 2017, which was three years after its opening. Relevant technical measures should be taken promptly to conduct targeted inspections to improve the safety of tunnel lining and prevent the deterioration of tunnel defects.