## 5 Solving Pareto Optimal Solution Set and Analysis Decision
### Pareto Optimal Solution Set and Analysis of Running 24 Pumping Wells Schemes  
Similarly, on the premise of meeting the constraints and control conditions, the third optimal working condition is set to arbitrarily close two of the pumping wells, resulting in a total of 325 layout schemes, which does not change the location of the wells in the preliminary layout scheme. After the optimization of the Gamultiobj program, the program converges to 100 sets of Pareto solution sets, and 100 feasible schemes can be optimized for the three objectives. Three sets of layout optimization schemes with evenly distributed Pareto solution sets under the third working condition are selected for analysis. Pareto optimal solution sets and the pumping well layout status are shown in Figure 9.  
It can be seen from Figure 9 that under the third optimization condition, the optimization model runs 24 pumping wells. Scheme 1 is to close the J19 and J22 pumping wells, scheme 2 is to close the J7 and J24 pumping wells, and scheme 3 is to close the J1 and J22 pumping wells. Similarly, all Pareto solutions of the three schemes under the third optimization condition are substituted into the dewatering multi-objective optimization evaluation system, and the evaluation scores are calculated. The weighted scores of the three objectives are arranged in descending order from larger to smaller. The score results of Pareto solutions of each scheme are shown in Table 9.  
Select the Pareto solution with the highest evaluation score in the dewatering optimization scheme in Table 9; that is, the three groups of dewatering schemes with the same weighted score of 89.455. The comparison of three objective optimization results is shown in Table 10. The optimization results of decision variables are shown in Figure 10. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Each Scheme**} & **Pareto** & **Score for** & **Score for** & **Score of** & **Weighted Scores of Three** \\  & **Solution No.** & **Objective I** & **Objective II** & **Objective III** & **Objectives of Dewatering** \\ \hline  & 1 & 95 & 90 & 90 & 90.545 \\  & 2 & 85 & 80 & 90 & 86.365 \\ Close J7 and J24 & 3 & 75 & 80 & 90 & 85.275 \\ pumping wells & 4 & 95 & 90 & 80 & 84.725 \\  & 5 & 75 & 70 & 90 & 82.185 \\  & 6 & 95 & 90 & 70 & 78.905 \\ \cline{2-6}  & 1 & 95 & 90 & 90 & 90.545 \\  & 2 & 85 & 80 & 90 & 86.365 \\ Close J7 and J24 & 3 & 75 & 80 & 90 & 85.275 \\ pumping wells & 4 & 95 & 90 & 80 & 84.725 \\  & 5 & 75 & 70 & 90 & 82.185 \\  & 6 & 95 & 90 & 70 & 78.905 \\ \cline{2-6}  & 1 & 95 & 90 & 90 & 90.545 \\  & 2 & 85 & 80 & 90 & 86.365 \\ Close J1 and J22 & 3 & 75 & 80 & 90 & 85.275 \\ pumping wells & 4 & 95 & 90 & 80 & 84.725 \\  & 5 & 75 & 70 & 90 & 82.185 \\  & 6 & 95 & 90 & 70 & 78.905 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Evaluation table for optimal scheme of foundation pit dewatering for running 24 pumping wells. Figure 9: Pareto set distribution diagram and pumping well working state under the third optimal working condition. (In the figure (**a,c,e**), the red dot indicates the relationship between the total water inflow and the settlement influence coefficient, the green dot indicates the relationship between the central water level drawdown and the total water inflow, the blue dot indicates the relationship between the central water level drawdown and the settlement influence coefficient). It can be seen from Table 10 that the total water inflow of objective I under the third optimized condition is about 1.43 \(\times\) 10\({}^{5}\) m\({}^{3}\)/d, the ground settlement value of objective II is about 7.95 mm, which is less than the allowable settlement value of 15 mm, and the foundation pit central water level of objective III is 1.83-1.84 m lower than the foundation pit bottom plate. In this scheme, due to the minimum number of pumping wells and pumping capacity, the cost of dewatering is minimized.