Study on the Characteristics of Surface Subsidence Induced by the Construction of a Subsurface Karst Tunnel Beneath an Airport

The tunnels in Southwest China are located in environmentally sensitive areas with intensive karst development and close proximity to airports. Surface subsidence in these regions poses serious risks to both tunnel construction safety and airport operational safety. In order to comprehensively analyze the characteristics of surface subsidence, this article determines the optimal test scheme for on‐site construction of the cantilever tunneling machine excavation method based on the comprehensive analysis of its geological characteristics, and combined with numerical simulation. At the same time, the deformation mechanism of karst strata and the influence of construction disturbance on subsidence are revealed through the Peck formula theory, and the mechanism and spatiotemporal evolution law of surface subsidence induced by karst tunnel construction are explored based on the on‐site monitoring data. The research shows that: (1) the subsidence deformation characteristics conform to the Peck formula; (2) the subsidence curves of multiple sections show that the cumulative subsidence law conforms to the rapid deformation stage, the slow deformation stage, the deformation acceleration stage and the deformation convergence stage, and has the universality of the four‐stage characteristics; (3) the subsidence amount is the largest during the excavation of the upper step, the subsidence amount is the smallest during the excavation of the lower step to the section, and the subsidence amount is at the middle level during the excavation of the inverted arch to the section. The four‐stage settlement pattern and key control procedures summarized in this study provide a direct basis for settlement prediction and dynamic adjustment in similar tunnel constructions in karst areas, offering important practical significance for ensuring airport operational safety.