A Simple Prediction Model for Mechanical Response of Lined Tunnels Incorporating Yielding Elements

The lining incorporating yielding elements has been proved to be the most effective solution for tunneling through severe squeezing ground. Unfortunately, there has not been a well-organized method to transfer its beneficial effects into the practical tunnel design. This study aims to provide an analytical model for predicting the behavior of yielding lining supported tunnel. The internal force analysis of the lining is first carried out to determine the optimal installation positions of the yielding elements. Second, the lining incorporating yielding elements is processed as a simplified shell using the equivalent deformation principle. The equation for calculating the elastic modulus of the simplified shell is presented. The analytical solutions for the tunnel displacement and lining pressure are provided in the viscoelastic Burgers rocks, where the installation delay of the lining and the tunnel face advancement effect are taken into account. The proposed analytical model is applied in the Saint Martin La Porte access adit of Lyon-Torino Base tunnel, where the yielding lining was employed. The analytical result provides a good prediction of the time-dependent tunnel convergences in the Saint Martin La Porte access adit. Finally, a comprehensive parametric investigation is performed, including the influences of installation time of yielding lining, yield stress and length of yielding elements. Some inspiring results for the tunnel design are provided.