## 4 Results
### Results of the Evaluation of Geological Factors  
#### 4.1.1 Terrain and Geomorphological Conditions  
(1) Landform  
The characteristics of landform types are an important consideration in the development of underground space. Nantong City is located in the east of China's coastline and the Yangtze River, surrounded by water on three sides. It lies within the alluvial plain of the Yangtze River Delta. Except for the hills and mountainous terrain along the Yangtze River Langshan Town, the rest of the area consists of plains. The overall terrain is relatively flat, with slight undulations in the land surface. Elevations range from 2 to 6.5 m, the highest point in the city being 108.5 m above sea level. The landform of Nantong City is relatively simple and can be divided into plains, hills, and mountains according to the change of terrain height. Some areas in the west of Nantong City have hilly and mountainous terrain, with complex topography, making them mostly unsuitable for development. The eastern coastal areas have lower terrain, mainly consisting of mudflats and river inlets, and thus form a vast mudflat area and some islands. The rest of the area is suitable for development, \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{**Pimary Indicators**}} & \multirow{2}{*}{**Weights**} & \multirow{2}{*}{**Secondary Indicators**} & \multirow{2}{*}{**Unit**} & \multirow{2}{*}{**Normalized Weight**} & \multirow{2}{*}{**Unsuitable**} & \multirow{2}{*}{**Less Suitable**} & \multirow{2}{*}{**Secondary**} & \multirow{2}{*}{**Most**} \\  & & & & & & & **Suitable** & & **Suitable** \\ \hline Terrain and geomorphological & \multirow{2}{*}{0.036} & Landform & / & 0.057 & Low mountain & Hill & Terrace & Plain \\ conditions & Slope & \(\circ\) & 0.110 & \(\geq\)23 & 14–23 & 6–14 & \(\leq\)6 \\ \hline \multirow{6}{*}{Engineering geological conditions} & \multirow{2}{*}{0.098} & Soft soil thickness & m & 0.050 & \(\geq\)15 & 10–15 & 5–10 & \(\leq\)5 \\  & & & & Highly affected by soft soil & bedrock depths & bedrock depth, no soft & Exposed bedrock, thin loose layers, soil influence & Exposed bedrock, thin loose layers, soil influence & Exposed bedrock, thin loose layers, soil influence & Exposed bedrock, thin loose layers, soil influence \\ \cline{1-1}  & & & rock and soil mass & / & 0.027 & deformable- & soft soft soil effects & Exposed bedrock depth, soil influence \\ \cline{1-1}  & & & soil mass & & & geotechnical properties & Exposed soil influence \\ \cline{1-1}  & & & Subgrade bearing capacity & kPa & 0.090 & \(\leq\)60 & 60–150 & 150–200 & \(\geq\)200 \\ \hline \multirow{6}{*}{Hydrogeological conditions} & \multirow{2}{*}{0.133} & Groundwater corrosion & / & 0.058 & High & General & Slight & No-affected area \\  & & Density of water systems & km & 0.018 & \(\leq\)4 & 4–7 & 7–10- & \(\geq\)10 \\  & & Water content of water-bearing formation & m\({}^{3}\)/d & 0.091 & 500 & 1000 & 1500 & 2000 \\ \hline \multirow{6}{*}{Sensitive geological conditions} & \multirow{2}{*}{0.053} & Distance to fault zones & km & 0.024 & \(\leq\)100 & 100–200 & 200–300 & \(\geq\)300 \\  & & Susceptibility of geological hazards & / & 0.143 & High & General & Low & No-affected area \\ \hline Ecological & \multirow{2}{*}{0.402} & Ecological reserve planning & / & 0.167 & Affected area & / & / & No-affected area \\ \hline \multirow{6}{*}{Regional development level} & \multirow{2}{*}{0.278} & Density of roads & km & 0.026 & \(\leq\)1.5 & 1.5–30 & 3–4.5 & \(\geq\)4.5 \\  & & House price & CNY/m\({}^{2}\) & 0.092 & \(\leq\)6000 & 6000–26,000–52,000 & \(\geq\)52,000 \\ \cline{1-1}  & & GDP per capita & CNY & 0.012 & \(\leq\)13,500 & 13,500–14,500 & 14,500–15,000 & \(\geq\)15,000 \\ \cline{1-1}  & & Population density & person/km\({}^{2}\) & 0.038 & \(\leq\)700 & 700–800 & 800–850 & \(\geq\)850 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Nantong underground space evaluation index weights and quantitative criteria.