# Multi-Objective Real-Time Planning of Evacuation Routes for Underground Mine Fires
## 5 Case Studies
### Simulation Result and Discussion  
It is assumed that the location of an underground evacuee is in a roadway at the lowest elevation of the underground mine, Level \(-245\). CO and smoke sensors are mainly located in the inlet and return airways of each production section and sub-section, as well as in the return air outlets of forced ventilation roadways. Assume that a fire occurs in the \(-110\) horizontal transport roadway at the bottom of the west wind shaft underground due to the aging of electromechanical equipment, and the smoke spreads along the ventilation system. The time sequence of the underground sensors alarming in sequence since the fire occurred is shown in Table 1. The range of the underground contaminated by smoke obtained by the algorithm search is shown in Figure 7. As shown in the table, the earliest smoke sensors located in the inlet airway detected the fire \(11\) s after its ignition. If no effective control measures, such as air reversing, are implemented or if these measures fail, all underground sensors will gradually trigger alarms over the course of approximately 1771 s. This indicates that carbon monoxide and smoke from the fire will spread to all underground locations. Based on the attributes such as smoke diffusion time generated by sensor data, the passability network of the underground roadways is assigned; then, the location of the underground personnel is taken as the starting point and the four surface safety exits of the main shaft, auxiliary shaft, inclined shaft, and air intake shaft and the two underground refuge chambers are used as escape targets. The route-finding process is constrained by the self-rescuer-rated protection time of 30 min according to the safety regulations. The equivalent length of the route and the hazardous time attribute are used as the path dominance attributes to obtain the routes for underground personnel to reach each escape location. Based on the dynamic programming labeling algorithm, the optimal route that meets the rated protection time of the self-rescuer and has a shorter equivalent length and travel time in the smoke stream is found. By prioritizing escape targets and escaping from \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sensor Serial Number** & **Alarm Time/s** & **Sensor Serial Number** & **Alarm Time/s** \\ \hline
2 & 11 & 19 & 847 \\
3 & 30 & 7 & 868 \\
15 & 233 & 5 & 1042 \\
20 & 288 & 12 & 1222 \\
16 & 314 & 1 & 1266 \\
8 & 346 & 13 & 1283 \\
9 & 496 & 18 & 1324 \\
6 & 621 & 14 & 1442 \\
11 & 818 & 17 & 1771 \\
4 & 846 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Sensor alarm time and sequence. Figure 7: Smoke diffusion pollution range of underground fire. the danger zone as early as possible, feasible evacuation routes are sorted. In addition, to investigate the effect of response time on route planning, we explored feasible avoidance routes for the same personnel location after 12 s, 300 s, and 1200 s of the disaster, respectively. The path visualization results are shown in Figure 8; the path sorting results are shown in Table 2: \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Respond** & **Priorities** & **Targets** & **Paths** & **emporary** & **Equal** & **Time in** \\
**Time** & & & & **Escape Time/s** & **Distance/m** & **Smoke/s** \\ \hline \multirow{4}{*}{12 s} & \multirow{4}{*}{2} & \multirow{4}{*}{3} & \multirow{4}{*}{2} & \multirow{4}{*}{46, 472, 467, 466, 385, 409, 422,} & \multirow{4}{*}{-} & \multirow{4}{*}{1811} & \multirow{4}{*}{0} \\  & & & & 421, 419, 43, 442] & & & \\  & & & & 446, 472, 467, 466, 385, 409, 422, & & & \\ \cline{1-1}  & & & 421, 419, 376, 430, 414, 382, 381, & - & 1991 & 0 \\ \cline{1-1}  & & & 32, 441] & & & \\ \cline{1-1}  & & 3 & Inclined shaft & & 35, 444] & & & \\ \cline{1-1}  & 4 & \(-\)245 level refuge & [446, refuge2] & - & 187 & 0 \\ \cline{1-1}  & 5 & \(-\)230 level refuge & [446, 472, 467, 466, 385, refuge 1] & - & 839 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Ranked results of evacuation routes.