## 1 Introduction  
Urban underground space resource (UUSR) is deemed as the second land resource for urban development. UUSR development is significant in achieving sustainable and resilient urban development. It serves various purposes, including mitigating the shortage of land resources, easing traffic congestion, reducing carbon emissions, and revitalizing surface ecological environments [1; 2; 3; 4; 5]. However, in certain areas, the development of UUSR may lead to disasters and accidents, such as ground collapse [6], settlements [7], and tunnel water gushing [8]. UUSR is normally developed in a certain geological body subsurface. The poor geological conditions are considered to be the fundamental constraining factor of underground space [9]. Neglecting the effect of UUSR development on the geological structure, groundwater flow, and stress field will cause an irreversible and unrecoverable risk to the city. [PERSON] et al. defined UUSR quality as the difficulty degree of UUSR development due to the influence and restriction of various geological environmental factors (GEFs) under certain technical conditions [10]. Assessing the UUSR quality based on GEFsholds paramount significance for facilitating scientific urban underground space planning and preparing for construction activities. An escalating number of scholars have acknowledged and undertaken systematic scientific assessments of UUSR, including suitability assessment [11; 12; 13; 14], potential assessment [15; 16], and quality assessment [17; 18]. Current UUSR assessment mainly depends on the 2D-based fuzzy mathematical model [19; 20], 3D GIS spatial data management, multi-factor overlay analysis, and 3D geological modelling technology [18; 21; 22]. The assessment indexes primarily comprise topographic features, engineering geological factors, hydrogeological characteristics, geological hazards, site conditions, and economic considerations. Topographic features will affect the connectivity between underground and above-ground spaces, as well as the excavation methods of underground spaces. Engineering geological factors include geological structures and soil and rock properties, which mainly affect the regional stability of underground spaces and the safety of engineering structures. Hydrogeological characteristics are mainly manifested in the depth of groundwater, types of water-bearing rock formations, and water abundance, and have an impact on the underground engineering construction. Geological hazards such as land subsidence and sand liquefaction can increase the difficulty of the underground engineering construction and pose safety hazards. Furthermore, site conditions, i.e., ground restrictions such as surface buildings, roads, squares, green areas, and reserve areas were considered in the assessment of urban underground space resources in Chongqing [23]. Economic considerations including population density, GDP per capita and ground price were considered in the suitability evaluation of underground space development in Wuhan [24]. The weights assigned to these assessment indicators are predominantly determined using the subjective analytic hierarchy process (AHP) using expert opinion [25; 26; 27], the objective entropy weight method (EWM) using the degree of dispersion of data in the indicators [18; 28; 29], and the combined weights method that considers subjectivity and objectivity [30], etc. Furthermore, the multi-objective linear weighting method [25], fuzzy comprehensive evaluation method [31], and multi-level grey evaluation method [32] are mainly utilized as the mathematical models for UUSR assessment. The multi-objective linear weighting method involves quantifying the indicators and linearly summing up the weights of the indicators. The fuzzy comprehensive evaluation method determines the membership degree of each evaluation indicator relative to each quality level through a membership function, and then determines the quality level through a fuzzy operator operation based on the maximum membership principle.