As large scale construction of highways in West China

more small spacing tunnels have been adopted due to the limitation of landscape. Because of the complexity of construction techniques，deformation and failure mechanisms of surrounding rock mass during excavation are complicated. Construction sequences and supporting time are important to the stability of rock mass and concrete lining. Effects of release proportion of the load and supporting time on stability of tunnel are studied based on construction characteristics of Qishucao Small Spacing Tunnel which belongs to Shanghai-Chengdu high-way. Numerical simulation results show that

as the lining constructed earlier

linings and anchors bear bigger load and the plastic deformation becomes smaller. Constructing the reinforced concrete lining in time can prominently control the deformation of the rock pillars and improve the stress condition of the surrounding rock mass. Achievements from the study can guide the design and construction of small spacing tunnel with similar conditions.