Geological suitability evaluation of underground space development in the Nanshan District of Shenzhen based on constraint conditions

Urban underground space resource is one of the vital resources of the city. Shenzhen is the city with limited land resources and urgently needs to carry out geological suitability evaluation of underground space to guide the development and utilization of underground space. However, the development of underground space resource is restricted by a variety of geological factors. It is necessary to use appropriate methods to evaluate the geological suitability of underground space development. Taking the Nanshan District of Shenzhen as the study area, this paper proposes a constraint evaluation system that takes the constrained geological factors as the first-level evaluation index and combines the geological background of the study area with the planning of underground space resources utilization in Shenzhen. The geological suitability of shallow underground space (0−15 m) and sub-shallow underground space (>15−30 m) in the study area of the conventional system and constrained system is evaluated by using the empirical score evaluation method and fuzzy comprehensive evaluation method. The results show that (1) compared with the conventional evaluation system, the constraint evaluation system improves the overall weight of the constraint geological factors. (2) According to the evaluation results of the constraint system, the poor and unsuitable areas are mainly distributed in the fault zone, high incidence of geological disasters and surface water area, which is more consistent with the actual geological conditions of the study area. (3) Attention should be paid to the geological problems such as stratum instability and ground collapse caused by sand liquefaction in the unsuitable areas during the development and utilization of the key development zones in planning. Meanwhile, geological problems such as rock fragmentation and groundwater enrichment in the region of restricted active faults should be avoided reasonably. This study strongly supports the planning of underground space resource utilization in the Nanshan District of Shenzhen.