Experimental and numerical study on staged construction pressure arch of super large section tunnel

There are more and more super large section tunnels. However, the calculated results by the traditional load calculation method are much larger than the real ones without considering the actual construction steps and support. Based on the method for discriminating the tunnel pressure arch, the dynamic development of pressure arch during the process of construction is studied by utilizing the large-scale two-dimensional model tests. It can be seen from the stress change around the hole that the pressure arch of large section tunnel forms in different regions by stages, along with the excavation steps. Then numerical analysis is conducted to verify and summarize the law found in the model tests. To study the restriction effect on pressure arch of support, a fine numerical model is established to simulate the construction conditions. The restriction effect on pressure arch of support is analyzed. Finally, the dynamic change of pressure arch and the reduction coefficient of arch height, which can be adopted to guide the design and calculation, are obtained.