# Dynamic Risk Assessment of Ultra-Shallow-Buried and Large-Span Double-Arch Tunnel Construction
## 4 Construction Dynamic Risk Evaluation Index Weight
### Base Weight Correction
The classification standard for the change in construction stage of each index can be based on the reference value of the risk evaluation index classification standard, as shown in Table 5.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Second-Level Indexes**} & \multicolumn{5}{c}{**Risk Level and Scoring Range**} \\ \cline{2-6}  & **I (90–100)** & **II (80–90)** & **III (70–80)** & **IV (60–70)** & **V (0–60)** \\ \hline Rock mass & \textgreater{}60 & 30–60 & 15–30 & 5–15 & \textgreater{}5 \\ strength U\({}_{11}\) & \textgreater{}50 & 30–50 & 10–30 & 5–10 & \textgreater{}5 \\ modulus U\({}_{21}\) & \textgreater{}50 & 30–50 & 10–30 & 5–10 & \textgreater{}5 \\ Weathering & Unweathered & Breeze & Moderately weathered & Strong weathered & Completely weathered \\ George U\({}_{31}\) & Groundwater & No water & Less water & Moderately water & More water & Abundant water \\ condition U\({}_{41}\) & Bad geological & No bad geology & Less bad geology & Poor geology exists & More bad geology & Abundant bad \\ conditions U\({}_{15}\) & Surrounding & No surrounding & Buildings of general & & & \\ Surrounding & No buildings & Secondary buildings & & & & \\ buildings U\({}_{21}\) & buildings & & importance & Important building & & buildings \\ Underground & No pipeline & Less pipeline & More pipelines & Dense pipeline & Pipeline must be & \\ pipeline U\({}_{22}\) & Branch road & Secondary trunk road & Trunk road & Expressway & & \\ Urban road grade U\({}_{23}\) & Branch road & Secondary trunk road & Trunk road & Expressway & Multiple roads and complex routes \\ Climatic & Good & Better & Generally & Poor & Very bad \\ conditions U\({}_{24}\) & Turned section & \textless{}10 & 10–30 & 30–50 & 50–100 & \textgreater{}100 \\ size U\({}_{31}\) & \textgreater{}30 & 22–30 & 15–22 & 8–15 & \textless{}8 \\ Tunnel depth U\({}_{22}\) & \textgreater{}30 & 22–30 & 15–22 & 8–15 & \textless{}8 \\ Design method & \textgreater{}10 & Reasonable & Basically reasonable & General reasonable & Poor & Unreasonable \\ rationality U\({}_{31}\) & Reasonable & Basically reasonable & General reasonable & Poor & Unreasonable \\ Reasonable load & Reasonable & Basically reasonable & General reasonable & Poor & Unreasonable \\ Structural & Unimportant & Basically important & General important & More important & Very important \\ importance U\({}_{38}\) & New technology & Few new technologies & General new & More new & Many new \\ application U\({}_{38}\) & Construction method & Reasonable & Basically reasonable & technologies & technologies & technologies \\ rationality U\({}_{41}\) & Reasonable & Basically reasonable & General reasonable & Poor & Unreasonable \\ Rationality of & Reasonable & Basically reasonable & General reasonable & Poor & Unreasonable \\ construction & Superior to design & Meet design standards & General quality & Below quality & Seriously unqualified \\ quality U\({}_{43}\) & Standards & & & quality & \\ Monitoring and & Strictly follow the & More perfection & General perfection & Imperfect & None Monitored \\ measurement U\({}_{44}\) & specifications & The arrangement of & & & \\ Skill level of & Perfect arrangement & & & & \\ workers U\({}_{45}\) & of technical staff & & & & \\ Construction & & & & & \\ organization & No omissions & & & & \\ management level U\({}_{51}\) & & & & & \\ Safety education and & Adequate training & More training & & & Less training & No training \\  & Emergency & Perfect emergency & & & & Incomplete emergency & \\ management U\({}_{53}\) & plan & Relatively complete & General perfection & plan & No contingency plan \\ Equipment material & New equipment & Relatively new & New equipment but & Equipment is new and & Serious aging of \\ protection U\({}_{54}\) & & equipment & poor maintenance & timely & & \\ Construction & No impact on & & & & \\ environment U\({}_{55}\) & construction safety & & & & & \\ Ground & S1 \(\leq\) 0.6 U\({}_{1}\) & 0.6 U\({}_{1}\) +S1 \(\leq\) 0.7 U\({}_{1}\) & 0.7 U\({}_{1}\) +S1 \(\leq\) 0.8 U\({}_{1}\) & 0.8 U\({}_{1}\) +S1 \(\leq\) 0.9 U\({}_{1}\) & S1 \(\geq\) 0.9  
After scoring the risk evaluation index according to the construction state, a vector was obtained and normalized to obtain the weight correction vector \(X\) (\(x_{1},x_{2},\ldots,x_{i}\)).