In order to solve the problem of testing the water pressure resistance of lining structures of water-rich tunnels and the difficulty of implementing the existing model tests, a large-scale model test method was proposed relying on the New Yuanliangshan Tunnel threatened by high pressure and rich water. This method creatively transformed the external water pressure of the lining structure into internal water pressure, and the conversion coefficient of water resistance of lining under different sizes and loading modes was obtained by numerical calculation. Results showed that the ultimate water pressure resistance of the lining structure under an external uniformly distributed water pressure and local water pressure was 1.44 and 0.67 times of that obtained from the large-scale model tests, respectively. By conducting the large-scale model tests and combining with the conversion coefficient, the water pressure resistance of the actual tunnel lining could be obtained. Research indicated that water pressure resistance of K2.0 (bearing water pressure of 2.0 MPa) type lining at the transition section of karst caves and K3.0 (bearing water pressure of 3.0 MPa) type lining at the section of karst caves of the New Yuanliangshan Tunnel was 3.33 MPa and not less than 4.36 MPa, respectively, and the high reliability of the large-scale model tests was verified by numerical calculation, implying that the model test method could be extended to similar tunnel projects.

Aiming at the difficulty in surrounding rock deformation control during the construction of deeply buried mined large-section metro stations, taking a large-section mined metro station on Chongqing Rail Transit Line 18 as the engineering background, this study adopts the expanded arch foot and bench method for station excavation and investigates the surrounding rock support effect during the construction process. A three-dimensional numerical model is established by using Midas GTS NX, and combined working conditions of support structures, including anchor bar, sprayed concrete, temporary support, steel arch and secondary lining, are set up. The control effects of different support schemes on surrounding rock are compared and analyzed from three aspects: displacement field, stress field and plastic zone distribution. Combined with field monitoring data, the rationality of the selected support scheme is verified. The research results show the following: (1) After the expanded arch foot and bench method is determined as the optimal excavation method for the station, the horizontal displacement of the side wall under the original support scheme exceeds the limit and fails to meet the specification requirements. (2) The surrounding rock control effect is positively correlated with the perfection degree of the support system. A single support form presents the weakest capacity in controlling surrounding rock deformation and stress. The addition of anchor bars and temporary supports can gradually improve the support performance. The composite support system of “anchor bar + sprayed concrete + temporary support + steel arch” achieves the optimal control effect, which can constrain arch crown settlement, ground surface settlement and horizontal clearance convergence within the specification limits, significantly reducing stress concentration and the scope of the plastic zone. (3) The deviation between field monitoring and numerical simulation results is less than 15.2%, which verifies the applicability and safety of the composite support system for station construction, adopting the expanded arch foot and bench method. The research findings can provide technical references for the support design and construction of deeply buried mined large-section metro stations under similar geological conditions.