The construction mechanical behavior and deformation characteristics of lining structure:a case study of large-span and small-clearance tunnels. (November 2022) - Zhang, Heng
Abstract: It is difficult to grasp the force of the lining of the tunnel with a long-span and small clearance, and the interaction between the two lines is complicated. There is a lack of design and construction experience in the world. Based on the Xinwu Tunnel with two-line and eight-lane, this paper adopts the method of field test and numerical simulation method to study the influence of the driving process of the trailing line on the mechanical properties of the leading line lining. On this basis, using the numerical simulation method, the influence of the different clear distances on the tunnel lining stress and the radial displacement around the tunnel is analyzed. The results indicated that with the excavation of the second tunnel, the axial force of the first tunnel lining all develop in the direction of pressure increase; the tensile stresses appearing in the sidewall far from the side of the middle rock column and the arch foot near the side of the middle rock column are larger, and the monitoring and measurement of its position should be increased during the construction to prevent the concrete from cracking. It is better to stagger the working face of the first and backward tunnel by 35 m to reduce the mutual disturbance brought by excavation; in the process of the second tunnel crossing a certain section of the first tunnel and moving away from it, the bending moment at the left and right sidewalls of the first tunnel will increase significantly, the sidewall bending moment value near the side of the middle rock column will increase to 3 times or substantially reverse the bending direction (eventually the outer side is pulled), and the sidewall bending moment value far from the middle rock column will increase by 25 %∼100 %.