Research on the disaster bearing characteristics system and capacity depth disaster response curves in urban underground three dimensional spaces.

The rapid development of urban underground space utilization, coupled with the increasing frequency of extreme precipitation events, has heightened the vulnerability of underground spaces to flood disasters, rendering flood prevention a critical challenge in underground infrastructure planning. While existing research predominantly focuses on pre-disaster early warning systems, in-disaster evacuation protocols, and post-disaster recovery strategies for underground flooding, systematic investigations into the disaster-bearing characteristics of underground spaces and the interrelationships among storage capacity, water depth, and disaster mechanisms remain notably deficient. To address these gaps, this study consolidates methods for identifying flood disaster-bearing characteristics in urban three-dimensional spatial contexts and establishes a comprehensive indicator system encompassing external flooding, underground waterlogging, and disaster-specific attributes. By defining the safe evacuation water depth at ground-level exits as a critical control threshold, we derive site-specific safe evacuation times and propose a methodology for constructing capacity-depth-disaster (C-D-D) curves to quantify flood resilience. These contributions provide a scientific foundation for abstracting representative underground space models, analyzing volume-dependent flood response mechanisms, and guiding integrated surface-underground disaster prevention planning at regional scales, thereby bridging theoretical research and practical decision-making in urban flood risk management.