The effect of a frictional interface in a preliminary yielding support for a deep tunnel

The increasing demand for fast interconnections in modern society leads to the construction of tunnels, bringing with it the necessity to overcome difficult conditions. When deep tunnels are excavated in poor ground, squeezing conditions occur and the design must follow the yielding principle. To this aim, special elasto-plastic elements embedded in the temporary support can be employed. The presence of the elasto-plastic elements radically modifies the interaction mechanisms making necessary the use of numerical analyses. Therefore, in this paper a numerical model of a vertical section of a circular tunnel with deformable preliminary lining are developed to study the soil-lining interaction. Through a parametric analysis, special attention is paid to the role of the interface mechanical behaviour between the structure and the ground by varying the interface’s friction angle.