Influence of Tunnel Excavation on Valley Slope Deformation and Mechanical Characteristics of Lining Structure

Based on the topography of the loess tunnel entrance through the valley, the finite element numerical calculation model was established, and the strength reduction method was used to analyze the influence of the left tunnel and the right tunnel on the stability of the valley slope, and the mechanical characteristics of tunnel lining structures under different construction schemes were further studied. The research results show that in the two construction schemes, the left tunnel excavation has a greater impact on the sliding surface and plastic zone of the slope, and has the greatest impact on the displacement of the slope toe. In addition, the tunnel excavation makes the lining structure of the leading hole more stressed, and the left tunnel excavation has a greater impact on the lining than the right tunnel excavation, but the left tunnel excavation is beneficial to the slope stability. Therefore, left tunnel excavation should be adopted in this type of unsymmetrial loading tunnel to reduce the disturbance to the slope by the tunnel excavation. At the same time, the design of the left and right tunnel lining should be strengthen according to the distribution pattern of the weak points on the inner side of the lining structure.