Model tests on soil deformation of surrounding soil of Luochuan tunnel

Based on the cross-section DK194+835 of Luochuan tunnel, model tests are conducted under different burial depths. The study involves to determine the parameters of the prototype, similar soil and lining through various experiments. Additionally, a set of new lining materials and connection methods are developed using the 3D printing technology to better simulate the shotcrete, steel frame and advanced small ducts in tunnel engineering. Various monitoring components, including self-made multi-point displacement meters, are used to collect data on the internal deformation of the surrounding rock and the surface settlement during excavation process. The test results demonstrate that the distributed support of the tunnel can be effectively simulated in the model tests through assembly, and sliding connectors can be used to link adjacent gypsum blocks. The vertical displacements at different measuring points exhibit a pattern of slow growth when the excavation surface is far from the monitoring section, the rapid growth as the excavation surface approaches the monitoring section, and the gradual stabilization after the excavation surface passes through the monitoring section. Furthermore, it is found that as the burial depth increases, the proportion of early deformation of the monitored section (i.e., the excavation surface moving away from and approaching the monitored section) decreases. The surface subsidence also undergoes three stages: slow growth, rapid growth, and gradual stabilization. Similarly, with the increasing burial depth, the proportion of early surface settlement of the monitored section decreases.