Determination of Stiffness of Circumferential Yielding Lining Considering the Shotcrete Hardening Property

The safety of circumferential yielding lining is influenced significantly by the shotcrete hardening property. However, presently, negligible research attention has been paid to this topic. This study aims to establish an analytical model for determining the support stiffness of circumferential yielding lining. Here, the shotcrete hardening property is considered. The entire deformation process of circumferential yielding lining is divided into three stages according to the mechanical characteristic of the yielding elements. A comparison of the element yield time and shotcrete age yields two cases that need to be discussed. Furthermore, analytical solutions for the time-dependent lining stiffness in different cases are proposed based on the previous shotcrete hardening equations. The corresponding equation for the lining pressure is also provided to evaluate the safety of shotcrete lining. The proposed analytical model is applied effectively in the Saint Martin La Porte access adit and predicts the average response of the monitoring tunnel convergences. Finally, a comprehensive parametric investigation is carried out, which includes the effects of yield stress, elastic modulus and length of yielding elements and ground stress on the shotcrete lining safety. Certain inspiring findings and effective recommendations for the design of circumferential yielding lining are provided.