The Study on Deformation and Mechanical Properties of Surrounding Rock to Primary Arch Cover Met

Abstract In order to explore the stress and deformation mechanism of surrounding rock in the construction process of the primary arch cover method, the finite difference method is used to simulate the construction process of the primary arch cover method of shallow buried large section hard rock tunnel. Combined with the monitoring data of the project site, the stress and deformation law of the tunnel surrounding rock under the influence of time and space effect are analyzed. In addition, the excavation process of the double-layer superimposed primary arch cover method and the traditional arch cover method is compared. Based on the stress and deformation characteristics of the tunnel surrounding rock, the technical advancement of the double-layer primary arch cover method is quantified. The results show that after the tunnel excavation is completed, the vertical displacement of the tunnel surrounding rock is mainly concentrated in the vault and arch bottom of the tunnel. The maximum uplift displacement is 7.263 mm and the maximum subsidence displacement is 14.09 mm. The settlement of the tunnel vault is roughly divided into three stages: slow settlement, rapid settlement and settlement stability; it can be seen from the comprehensive longitudinal span and section monitoring data that the double-layer superimposed primary arch cover method can better reduce the deformation of surrounding rock and increase the stability of the tunnel during excavation.