## 3 Case Study  
### Data Description and Preparation  
The raw data of this case study were mainly sourced from the site inspection and maintenance records of the deformation joints, 1104 in total, of a cast-in-situ double cabin utility tunnel project located in a city in Jiangsu Province, China. The raw data included the serial numbers of deformation joints, state descriptions (such as leakage, exudation, corrosion, crack, deformation, etc.), waterproof failure judgments, the environment conditions, maintenance records and the reasons for failure of the deformation joints. Specifically, waterproof failures are identified if there are leakage phenomena of water dripping, outflow or inrush in deformation joints, or the exudation area exceeds the standard. The time interval from the start of operation to the occurrence of waterproof failure is defined as the initial failure time. Once the waterproof facilities of deformation joints are repaired, the start of the failure time refers to the completion time of repair.  
The data preparation process involved data cleansing, classification and standardization. As analyzed in Section 2, the required data for the case study of joint waterproof facilities included the failure time (unit: days) and the covariates of the field environment conditions. From the start of operation of the utility tunnel in June 2018 to June 2019, a total of 90 deformation joint failure data were recorded along with the required field condition information. A sample of the recorded data (translated from Chinese) after the preparation processes is showcased in Table 1, which will be further explained by Tables 2 and 3 in the following Section 3.2.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \begin{tabular}{c} **Number of** \\ **Data Records** \\ \end{tabular} & **Failure Time** & \begin{tabular}{c} **Groundwater** \\ **Type** \\ \end{tabular} & **Repair** & **Quality Defect** & \
\begin{tabular}{c} **Geological** \\ **Condition** \\ \end{tabular} &
\begin{tabular}{c} **Foundation** \\ **Treatment** \\ \end{tabular} \\ \hline
0 & 100 & Unconfined & Without & Without & Medium & Without \\ \hline
1 & 34 & Unconfined & Without & Without & Medium & Without \\ \hline
2 & 28 & Unconfined & Without & Without & Soft soil & With \\ \hline
3 & 28 & Unconfined & With & With & Medium & Without \\ \hline
4 & 62 & Unconfined & Without & Without & Medium & Without \\ \hline \(\ldots\) & \(\ldots\) & \(\ldots\) & \(\ldots\) & \(\ldots\) & \(\ldots\) & \(\ldots\) \\ \hline
85 & 73 & Unconfined & Without & Without & Medium & Without \\ \hline
86 & 15 & Unconfined & With & With & Soft soil & With \\ \hline
87 & 243 & Unconfined & Without & Without & Medium & Without \\ \hline
88 & 312 & Unconfined & Without & Without & Medium & Without \\ \hline
89 & 19 & Unconfined & Without & Without & Medium & Without \\ \hline \hline \end{tabular}
\end{table}
Table 1: A sample of the recorded deformation joint failure data.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \begin{tabular}{c} **Factors** \\ \end{tabular} & \begin{tabular}{c} **Failure Reasons** \\ \end{tabular} & \begin{tabular}{c} **Influence Modes** \\ \end{tabular} \\ \hline \begin{tabular}{c} Component wear-out \\ \end{tabular} & \begin{tabular}{c} Waterproof components such as membranes and \\ waterstops reach their service life and lose their \\ waterproofing functions. \\ \end{tabular} & Long-term influence with certain regularities \\ \hline \begin{tabular}{c} \end{tabular} & \
\begin{tabular}{c} External construction activities damage \\ waterproof components or cause excessive \\ deformations that lead to the failure of \\ waterproof facilities. \\ \end{tabular} &
\begin{tabular}{c} Contingent influence that can be avoided by \\ setting safeguarding zones \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 2: Possible reasons for the failure of the joint waterproof facilities of cast-in-situ utility tunnels.