Discrimination, mechanical mechanisms, and control technologies for large deformation in tunnel surrounding rock: A state-of-the-art review

Abstract

Large deformation of surrounding rock presents a critical challenge that urgently requires attention in tunnel engineering. This study provides a systematic review of the definition, classification, grading, mechanical mechanisms, and control techniques related to large deformations in surrounding rock. First, the origin of the large deformation concept is systematically analysed, and different types of large deformations are categorized based on factors such as stratum properties, environmental conditions, and deformation causes. Representative grading methods for large deformations are summarized and critically evaluated. Subsequently, the mechanical mechanisms and existing analytical methods for various types of large deformations, such as those encountered in soft rock and squeezing rock, are thoroughly examined. Moreover, this paper identifies key directions for future research breakthroughs in understanding deformation mechanisms. Finally, principles and measures for controlling large deformations are elaborated, including strategies for selecting support systems and construction methods for tunnels in areas prone to large deformations. Additionally, the methods for predicting large deformations in surrounding rock are introduced, laying a foundation for rational and effective deformation control.