## 1 Introduction  
With the increase in the urbanization level and the continuous growth of the population, urban land resources are becoming increasingly tighter, which further triggers traffic congestion, environmental pollution, resource shortage, and other \"urban diseases\", seriously restricting the sustainable development of cities [1, 2]. With limited land resources, the unlimited planar expansion cannot effectively alleviate the phenomenon of \"urban disease\"; therefore, urban construction should shift from horizontal expansion to three-dimensional development, the incorporation of both ground and underground buildings, coupled with the coordinated development of an organic urban structure [3, 4]. The development of urban underground space (UUS) to enhance the comprehensive carrying capacity of the city and achieve sustainable and healthy development has become a consensus [5,6]. Urban underground space resources (UUSRs) belong to non-renewable resources, and their development process is characterized by irreversibility. Blind and disorderly development will not only lead to inefficient utilization of resources, but also cause a series of safety hazards during the construction process [7,8]. Therefore, an accurate assessment of the suitability of urban underground space development is essential for ensuring rational development and achieving sustainable urban development [9,10]. A comprehensive and scientific evaluation index system is an essential prerequisite for assessing the suitability of underground space development [11]. When selecting indicators, factors such as engineering geological conditions, hydrogeological conditions, terrain, and geomorphology conditions are often chosen as important assessment criteria [12, 13, 14]. With the increasing occurrence of safety accidents in underground engineering projects, some scholars have included geological sensitivity factors, such as the distribution of fault zones and the liquefaction of sandy soil, into the evaluation scope [15,16] to enhance the reliability and safety of development. Additionally, to ensure that UUSR development generates positive benefits for urban development, some studies consider economic factors such as GDP per capita and housing prices during the evaluation [17,18]. In assessing the suitability of urban underground space (UUS) development, methods such as AHP [19,20], the entropy weight method [21], fuzzy mathematics [22,23], and Bayesian Networks [10] are commonly used to construct evaluation models. From the above, it can be seen that scholars have only considered geological factors and economic factors when evaluating the suitability of UUS, and the research angle is relatively simple. In fact, the suitability of underground space development is closely related to the regional development level, which widely covers economic, social, infrastructure, and other aspects. Therefore, it is necessary to combine the social and economic analysis with the regional development level to ensure that the development and utilization of underground space is in line with the characteristics of the overall development of the city, so as to achieve the maximization of economic benefits. At the same time, under the concept of sustainable development, vigorously promoted nationwide, ecological protection gradually replaces economic benefits as the primary consideration, so the evaluation of the suitability of underground space development cannot be separated from the constraints of ecological preservation. The development of UUS should be constrained by ecological preservation, with development strategies aligned with the regional development level, so as to promote the sustainable development of the city. In addition, due to the differences in engineering geological conditions, hydrogeological conditions, and the development level of different study areas, the influencing factors of underground space development have obvious regional variability. For example, the Beijing area is affected by fault zones and river distribution [23].