Abstract:  In this study, the development history of tunnel rehabilitation and expansion in China over the last 20 years is investigated. Furthermore, the cases of additional tunnels, insitu expansion tunnels, combined expansion tunnels, and rehabilitated tunnels are summarized, and the development status of the research magnets, including rehabilitation and expansion modes, construction methods, construction mechanical responses, support parameters design and optimization as well as safety control of tunnels are examined, and their corresponding shortcomings are proposed. The specifications are as follows: first, the evaluation indices of various projects differ in terms of rehabilitation and expansion modes, and there is no standard guideline. Second, the design is more conservative in terms of construction methods, and it is critical to research how to realize efficient construction based on the existing tunnel lining. Third, in terms of the construction mechanical responses and support parameters, the field monitoring, calculation, and numerical simulation results of several projects vary, and there is no study on the development laws of surrounding rocks′ deformation, stress, and plastic zone under complex dynamic loading condition, which shows that more project applications should be studied, and an analysis system should be established for support parameters optimization. Fourth, in terms of the construction safety control, considerations should be made for blasting vibration reduction, support layout optimization, local reinforcement of weak surrounding rock, and construction auxiliary measures as well as the development of a quantitative index system for evaluating risk sources. Finally, the tunnel rehabilitation and expansion project′s development directions of standardized design, information management, green construction, and rapid construction are prospected.

Key words: highway tunnel, tunnel rehabilitation and expansion, construction method, safety control, support parameters