Adaptive adjustment strategy for earth pressure balance (EPB) operation parameters for pre-control of shield tunneling-induced surface settlement: a case study

During shield tunneling, ground deformation poses significant safety risks. The full optimization strategy ignores interactions between parameters, resulting in suboptimal performance in the pre-control of settlement in earth pressure balance shields. To address this problem, this paper proposes an integrated strategy that combines optimization and inversion, minimizing parameter interaction interference through adaptive adjustment of shield operation parameters. This mechanism performs an optimization search on the key operation parameters for settlement control, while the remaining operation parameters are predicted through inversion. Taking the Changchun Metro Line 6 project as an example, a bidirectional long short-term memory (Bi-LSTM) model enhanced by a multi-head self-attention (MHSA) mechanism is used to predict shield tunneling-induced settlement with spatiotemporal sequence dependency relationships. Particle swarm optimization and a random forest algorithm are used for optimization and inversion operations in the integrated mechanism, respectively. Subsequent ring position tests showed that the integrated mechanism-based adaptive adjustment strategy limited the average fluctuation of uncontrollable parameters to ±13.95% compared to ±34.27% for the full optimization strategy. The actual average settlement was only 3.81 mm compared to 4.72 mm for the full optimization strategy through collaborative parameter adjustment. The application validated the feasibility and applicability of the integrated mechanism, providing important references for the adaptive adjustment of shield parameters and tunnel construction automation.