Study on Ground Movements Caused by Shield Tunnelling Considering Multiple Karst Caves Coupling Effect

To address the ground movement caused by shield tunnels successively side-crossing karst caves, this study establishes a three-dimensional finite element model simulating shield tunnelling through dual adjacent caves along the Guangzhou East to Huadu Tiangui Intercity Railway project. The model was validated through field monitoring data to systematically investigate the impacts of cave treatment methods, grouting material parameters, and shield tunnelling parameters on ground deformation. The results reveal that untreated caves increase surface settlement by 15%-40%, with the nearest cave exerting dominant influence on adjacent monitoring points. Settlement exhibited positive correlation with cave dimensions. Although increasing grout elastic modulus to 100 MPa moderately reduced surface settlements, its effectiveness became constrained under full-cave filling conditions. A 25% reduction in face pressure doubled surface settlement. Critical thresholds were identified: horizontal cave-tunnel distances exceeding twice cave width stabilized surface settlement above the tunnel, and caves located at tunnel's lower side reduced vault settlement by 12%. The study proposes prioritizing treatment of adjacent large-scale caves and maintaining optimal face pressure as essential control measures, providing theoretical guidance for hazard prevention in karst tunnel engineering.