A genetic algorithm-based approach for optimizing the interface configuration of segmental joints considering bending stiffness and bearing capacity

The joint interface is a critical component of the segment lining structure. However, its current design largely depends on analogy and empirical methods, which often prevent the joints from fully utilizing their load-bearing capacities, specifically, bending stiffness and bearing capacity. To address this limitation, first, a refined 3D numerical model was developed, capable of parametrically modelling the joint and automatically determining its bending stiffness. Second, a multi-objective optimization model was formulated, incorporating both bending stiffness and bearing capacity as performance criteria. This model was solved using a genetic algorithm-based approach. Third, the effectiveness of the optimization method and the influence of key parameters were systematically investigated. Finally, refined numerical models of the segment lining structure were established to evaluate the effects of joint configuration optimization on the mechanical performance of the overall structure. The results demonstrate that the proposed optimization method is highly effective. The maximum increases in bending stiffness and bearing capacity of joints with single and double waterproof structures were 16.9% and 19.8%, and 11.0% and 11.0%, respectively. The variation ranges of bending stiffness and bearing capacity for joints with single and double waterproof structures were −9.5–30.5% and −5–18.3%, respectively, indicating the necessity of optimizing joint interface parameters. For joints with a single waterproof structure, both bending stiffness and bearing capacity exhibit greater improvements after optimization when the axial force is higher or the weight coefficient assigned to bending stiffness is lower. Moreover, the influence of the bending stiffness weight coefficient on the optimization outcomes diminishes as the axial force increases. For joints with double waterproof structures, axial force has a relatively minor influence on the optimization results. When both the axial force and the weight coefficients of bending stiffness are either relatively low or high, the weight coefficient exerts a more significant impact on the optimization outcomes. Optimizing the interface configuration of the segmental joint can effectively control the deformation of the lining structure, with reductions in radial displacement ranging from 13.91% to 52.92%. Additionally, the bending moment and joint opening at the localized position are significantly reduced following optimization.