Abstract: The layout of disc cutters significantly influences tunneling efficiency and cutter service life in shield tunneling. To enhance cutterhead operational stability during tunneling, a multi-objective optimization framework for shield disc cutter layout based on an improved conical shield model (CSM) is proposed. Considering the positions of the disc cutters as the polar radius and polar angle, and incorporating the effect of lateral forces on cutterhead stability, an improved CSM model is developed to enable a comprehensive multidimensional force analysis of the cutterhead. Accordingly, the corresponding models are used to estimate the total radial force and overturning moment. Taking the allowable center-of-mass offset of the cutterhead and other constraints into consideration, a nonlinear multi-objective optimization model is formulated to simultaneously minimize the total radial force and overturning moment. In accordance with the computational complexity, a non-dominated sorting strategy is integrated into a particle swarm optimization algorithm to solve the problem efficiently. The proposed method is validated through a real-world application to the Nanjing Metro Line 4, supported by simulation testing. Results demonstrate that the model generates multiple feasible layout solutions within 531 seconds while maintaining acceptable parameter sensitivity. Compared with the single-objective optimization approach, the proposed method can reduce the total radial force and overturning moment by 91% and 99%, respectively. Furthermore, it exhibits strong computational robustness across optimization problems of varying scales. In comparison with the traditional layout method, the lateral-force-informed approach can improve the cutterhead stability by 85.07%.

Key words: shield, disc cutter layout, improved conical shield model, lateral force, multi-objective optimization, particle swarm optimization algorithm