Model Test Study on Spatial Deformation Law of Surrounding Rock for Super-Large Section and Shallow Buried Tunnels

With the Ganggou Tunnel of the Jing-hu High-Speed Connection Line Road acting as the engineering background, a three-dimensional assembled large-scale geomechanical model test system was developed. The system includes a strain field monitoring system based on static strain acquisition and a displacement field acquisition system based on raster monitoring. Model tests on the excavation process of a super-large section and a shallow-buried tunnel with a small space were conducted. Data of surface subsidence, vault, and horizontal displacement were collected during excavation. When partially excavating the tunnel using the double sidewall guiding method and the Center Diaphragm method, displacement and disturbances mainly occurred within the ranges of one diameter distance to work face. The displacement spatial variation laws of the right and left tunnels are similar during excavation, and the magnitude of displacement in the right tunnel is larger because of the secondary disturbance superposition effect. After continuous rainfall for 40-50 min, the deformation of the surrounding rock significantly increased because of the rainfall effect; the overall stability of the surrounding rock was threatened. The research methods and the results obtained in this study will guide similar engineering approaches.