Abstract:  Mature artificial segment selection experience logic and reasonably simplified computation model are rooted in the segment automatic selection decision algorithm′s kernel to avoid the hidden dangers of manual segment ring selection to the posture of a shield and the quality of formed segments. Additionally, the construction parameters influencing ring selection are taken as the study object, and a complete analysis of shield tail clearance, propulsion cylinder stroke difference, and shield trend based on the ring selection computation approach and decisionmaking algorithm is proposed. Furthermore, all the feasible value ranges of each influencing factor in the actual construction and their weight change under various construction conditions are considered in advance. The approach is the first algorithm developed for eight groups of shield tail clearances and six groups of cylinder strokes based on the characteristics of largediameter shields, realizing an intelligent selection of universal segment parameters using an intelligent shield tail gap measuring and monitoring screen parameter image recognition module. The method′s field applicable results in several projects indicate that the segment selection algorithm that meets field operation requirements is reasonable, can standardize or replace manual segment ring selection and ensure the  complete quality of tunnel and shield tunneling posture.

Key words: shield, segment ring selection, weight distribution; large-diameter shield, image recognition, intelligent monitoring; automatic selection algorithm