Strategic path for high-quality development of urban underground space in the Yangtze River Delta region under geological safety constraints

As one of China’s most dynamic economic regions, the Yangtze River Delta (YRD) has approached the upper limit of surface land development, making underground space a critical strategic resource for urban renewal, compact spatial restructuring, and resilient city construction. Nevertheless, rapid expansion of underground development, combined with increasingly tight surface constraints, has led to the superposition of multiple geological hazards, which has become a key bottleneck restricting high-quality underground space utilization in the YRD. Based on comprehensive geological safety assessments of YRD cities, this study identifies six major geological risks, namely, land subsidence, karst collapse, landslides and debris flows, mining-induced subsidence, earthquakes, and road ground collapse, and analyzes their impacts on underground space planning, construction, and operation. Key challenges include insufficient understanding of deep geological structures, inadequate risk assessment systems, significant engineering-induced disturbances, and weak regional coordination. Correspondingly, this study proposes a set of policy recommendations: establishing multi-scale geological survey systems for underground space, developing resource evaluation and access mechanisms under geological safety constraints, enhancing region-wide collaborative planning and regulation, improving risk monitoring and early-warning capabilities, and fostering technological innovation. These strategies will support the YRD in becoming a national demonstration zone for high-quality underground space development and contribute to the modernization of China’s urban spatial governance.