A comprehensive hybrid method for performance evaluation of a modified earth pressure balance shield machine in mixed strata

The complex geological conditions and operational performance of reconditioning modified earth pressure balance shield (M-EPBS) machines can critically influence tunnel excavation and construction safety. To address this, the study proposes a comprehensive framework for assessing the overall construction performance of reconditioned shield machines in compound strata. This framework employs fuzzy mathematics theory and analytic hierarchy process (F-AHP) to construct a three-level multi-factor evaluation matrix and establish comprehensive membership function relationships. We then quantify the weight of each factor and the interval membership function, followed by a relative superiority analysis of the interval matrix. A shield tunneling case study is utilized to evaluate the model, focusing on layer conditions, shield design parameters, and shield construction parameters. The study also addresses the challenges encountered during the tunneling process and the corresponding countermeasures. The results reveal that the proposed framework is effective, user-friendly, and adaptable for selecting and evaluating M-EPBS machines in compound strata. This framework provides a novel approach for feasibility assessments, safe operation management, pre-shield design evaluations, and post-shield construction verifications.