Quantitative evaluation of influence of the soil transportation mode on the excavation efficiency for a shield tunnel based on the Markov chain.

This article focuses on analyzing the impact of two soil transport modes—continuous belt conveyor and rail train—on the excavation efficiency and expected profit of earth pressure balance (EPB) shield tunneling, using a Markov chain model. The study applies this model to the Beijing Metro New Airport Line first-phase project, defining ideal and non-ideal excavation states to quantitatively evaluate performance. Results indicate that the continuous belt conveyor mode maintains a higher proportion of ideal excavation states, leading to greater excavation efficiency and increased expected profits over time compared to the rail train mode. The findings provide a theoretical and practical reference for selecting soil transport methods in shield tunneling projects, emphasizing the advantages of continuous belt conveyors in long-distance urban subway construction.