Abstract:By the in-situ test of Sanshilipu tunnel,the mechanical characteristics of tunnel lining in shallow-buried loess are studied,such as the spatial distributions and temporal changes of surrounding rock pressure,bolt axial stress,surface strain of shotcrete,reinforcement stress and concrete strain in secondary lining. The results show that the maximum stress released in surrounding rock takes place in 7–10 days;the bolt axial stress stabilizes in about a month and in some area exist compression forces;surface strain of shotcrete is relatively great and fluctuates discontinuously;and the reinforcement stress in secondary lining is firstly tensile. The stress value gradually stabilizes in 6–8 days near side wall but continues decreasing near arch;and the strain in secondary lining changes from tensile to compressive states. The results provide support for optimization and give references to future design and construction.