Abstract: Recently, a new type tunnel emerges with these main feathers of super-large, cross-section and ultra-shallow. However, there are no relevant technical standards for the design and construction of the station tunnel at present. Taken Hongqihegou Station tunnel in Chongqing Metro 3rd line as the engineering background, a novel excavating method named the cross rock pillar method was developed by considering the advantages and disadvantages of the former methods of tunnel construction. A geomechanical model test was used to monitor stress and deformation of surrounding rock mass of the station tunnel during the process of excavation. The stress and displacement of surrounding rock were comprehensively analyzed during each step excavation. According to the geological parameters of the tunnel, a numerical analysis model was established based on ABAQUS software. By comparing monitoring results with numerical results, it indicates that the variation laws of stress and displacement are essentially the same. It is proved that the model test effectively reveals the variation laws of the stress and displacement of the tunnel. Therefore, this study provides valuable experience and useful guidance for the construction of similar projects in the future.

Key words: tunnelling engineering, super-large cross-section, ultra-shallow, cross rock pillar method, model test