The utilization of urban underground space resources (UUSR) are important approaches to effectively save land resources, improve the living environment, expand the urban space, and achieve sustainable urban development. To obtain accurate UUSR evaluation results, the weight assignment of indicators plays an important role in the evaluation process and is an indispensable part of it. Reasonable weights of indicators can greatly improve the accuracy of the final UUSR evaluation results. Neither the basic characteristics of cross-section data and time series data of UUSR evaluation indicators are taken into consideration simultaneously, nor is the combination and cross application of different weighting methods in the previous weight assignment of UUSR evaluation indicators. Considering the influence of the time dimension, the weighting method of time dimension is introduced into the UUSR evaluation. Through integrating the classical entropy weight method, which is a frequently-used weighting method of indicator dimension with the weighting method of time dimension in two different approaches by time ordered weighted averaging (TOWA) operator, the hybrid weight assignment model named entropy and time weighting model (E-TW) for UUSR evaluation is proposed. The experimental calculation results show that the UUSR evaluation results using the E-TW model are significantly better than the results using the single classical entropy weight method, which means the hybrid weight assignment model is more suitable for UUSR evaluation than the single weighting method of indicator dimension.

With the rapid advancement of urbanization, the development and utilization of urban underground space resource (UUSR) has become one of the dominant features. However, in certain areas, the development of UUSR may cause disasters and accidents, such as ground collapse, settlements, and tunnel water gushing. Geological environmental factors (GEFs) are recognized as the fundamental constraining factor of UUSR development. In this paper, quality based on GEFs is defined to assess the development difficulty degree of UUSR. A 3D assessment framework is proposed based on 3D geological modelling and the interval continuous mathematical model (ICMM). The subjective and objective joint weight method of analytic hierarchy process and entropy weight method (AHP–EWM) is utilized to determine the weight of each indicator. The quality index (QI) of each spatial node of the 3D geological model is calculated by the ICMM mathematical model. A case study conducted in the Jiangbei New District of Nanjing, China, serves as a demonstration of the UUSR assessment. The results clearly illustrate the 3D distribution characteristics of the quality in the study area, offering valuable insights for future 3D urban underground space planning.

Urban underground space resource (UUSR) constitutes a critical natural resource and a vital component of the natural environment, whose rational utilization is essential for the sustainable development of cities. Mathematical models are indispensable for the multi-object evaluation of UUSR. However, in previous research based on traditional mathematical models, neither the continuous expression of evaluation results has been considered, nor has the comparability been addressed. In this paper, the interval continuous mathematical model (ICMM) is presented at the theoretical level for UUSR multi-object evaluation. By achieving the continuous distribution of quantitative values of evaluation indicators, removing the step-like output features of evaluation results, and eliminating predefined grade boundaries, the ICMM achieves continuous expression of the results and improves their comparability across different areas. The correlation analysis conducted on the UUSR evaluation indicators demonstrates a significant monotonic relationship between the indicator value and the evaluation result, regardless of the increasing trend or the decreasing trend. Finally, a numerical experiment clearly demonstrates that the ICMM is valid for evaluating different UUSR objects.