Abstract:The new tunnel runs under the existing urban roads. When the buried depth is shallow, the upper road is easy to cause the pavement structure cracking and even damage due to excessive settlement. Therefore, it is necessary to study the construction technology of the tunnel. Based on the underpass project from Kaiyuan Road to Jianyuan Road in Xian, the finite element software is used to simulate the influence of pipe curtain supporting on the tunnel structure, surrounding rock stability and upper road pavement settlement during the construction of multi-arch tunnel. The main conclusions are as follows: (1) The maximum vertical displacement of the surrounding rock of the new multi-arch tunnel is 7.4 mm, which meets the requirements of the specification, and the tunnel structure is safe and reliable. (2) When the pipe curtain method is used, the maximum settlement of the pavement is only 4.39 mm, which indicates that the pipe curtain method is feasible to excavate the multi-arch tunnel under the existing urban road. (3) The minimum safety factor of the secondary lining of the tunnel constructed by the pipe curtain method is 2.05, which is greater than the minimum safety factor of the specification, and the lining structure is safe and reliable. In summary, using the pipe curtain method as the advanced support measure, the multi-arch tunnel crossing under the existing urban road has less influence on the upper pavement, and the construction safety risk is low.