# Suitability Evaluation of Urban Underground Space Development: A Case Study of Qingdao City
## 1 Introduction
This method is based on the engineering geological conditions of the underground in the study area and the urban planning demand conditions above ground and evaluates the suitability of urban underground space development based on various factors. This method is also a commonly used method to evaluate the development potential of underground space, which is also used in this study. Due to the lack of land resources in Qingdao's main urban area due to the excessive mountain area and its important economic and strategic location, the development of underground space is very important. Therefore, this paper chose Qingdao as the research area. Different from previous studies, this study also integrated the engineering geological conditions and urban planning requirements of the study area and conducted in-depth research and analysis on various factors affecting underground space development in the main urban area of Qingdao, China, including geological conditions, surface construction status, and urban planning requirements. After selecting influential factors that impact underground space development, the study used them as evaluation indicators for assessing the adaptability of urban underground space development ([PERSON] et al., 2018). Based on these indicators, suitability evaluation systems for shallow and medium-depth underground space development in Qingdao were constructed. The study then assigned weights to the indicators in the evaluation system and compared the weight assignment results obtained from different methods. There are many kinds of data used in the evaluation system, so there are some errors in the evaluation results when using these data for suitability evaluation. In order to reduce the impact of these errors on the evaluation results, both a multi-objective linear function weighting model and a fuzzy comprehensive evaluation model are utilized to evaluate the suitability of urban underground space development in Qingdao's main urban area, followed by a comparative analysis of the evaluation results. In recent years, fuzzy logic has emerged as a vital tool in various fields due to its unique advantages in handling complex and uncertain environments. For instance, [PERSON] et al. (2018) utilized fuzzy logic to analyze the feasibility of tidal turbine installations. Their research demonstrated the robustness of fuzzy logic in addressing multiple uncertainties, such as tidal forces, environmental impacts, and economic viability. By considering these factors holistically, fuzzy logic provided a reliable assessment tool, enabling researchers to conduct more precise feasibility analyses in complex natural settings. This example illustrates that fuzzy logic, as a method for managing complexity and uncertainty, holds broad application prospects. This study aims to build on these successful experiences by further exploring the application of fuzzy logic in the evaluation of the suitability of underground space development, providing new perspectives and methodologies for the relevant field. Ultimately, drawing from the evaluation findings, the study offers a scientific foundation and guidance for the future planning of underground space development in Qingdao. Scientific and reasonable evaluation of the suitability of underground space development is of great significance to the future development of cities.