Abstract: Urban deep underground space (at depths of over 50 m) is a strategic highland for alleviating the shortage of urban land resources and enhancing urban resilience, as well as the core carrier for implementing the national strategy of “marching towards the deep earth” and fostering new quality productive forces in the deep earth. In response to the current technical bottlenecks and social resistance in deep earth development, the core challenges are systematically analyzed, an application scenario framework is constructed, key technology system is improved, and the path for its large-scale, safe, and sustainable development is clarified. Technical challenges include the nonlinear mutation of the deep “three-high” (high ground stress, high geothermal temperature, and high hydraulic pressure) geological environment, micro-disturbance construction in high-density areas, lack of health protection in deep underground human settlements, and high operation and maintenance costs; social challenges include public psychological resistance, ambiguous ownership definition, and shortcomings in green and low-carbon technologies. On this basis, four core application scenarios are prospected: efficient circulation, green energy hub, safety and resilience barrier, and cuttingedge scientific and technological innovation. A full-chain key technology system including three-dimensional (3D) ownership collaborative planning and “Transparent Earth” precise exploration is constructed. A complete research framework of “Challenge-Scenario-Technology-Guarantee” is established, a diversified application scenario spectrum is innovatively constructed, human factors engineering are integrated into the construction of healthy deep underground environments for the first time, and a 3D ownership collaborative planning model, which can provide theoretical support and practical paths for the development of urban deep underground space in China and help cities transform towards deepening, intensification and intelligence, is established.

Key words: urban deep underground space, application scenario prospects, key technology system, resilient disaster prevention, human factors engineering