Stress Mechanism of Lining Structure of High Geothermal and Deep-Buried Tunnel

To study the behavior of stress varying with the ambient temperature in lining structures of high geothermal and deep-buried tunnels, a laboratory model test was designed to measure the structural stress of a tunnel model at various temperatures. Then, a numerical simulation analysis of the model test was conducted. A comparison of the two groups of data revealed that the axial force values obtained by model test were approximately 20% larger than the simulated values, but their distribution trend are similar, and the structural safety factors were approximately equal. Taking a tunneling project as an example, the numerical simulation method was adopted to analyze the effect of insulating layer on the stress characteristics and safety of the tunnel lining structure at 60 ℃ under a buried depth of 1 000 m. The results show that the insulating layer has a small effect on both the internal force distribution pattern of the supporting structure and the internal force of the primary lining and the cast concrete lining. The insulting layer, however, can remarkably improve the stress state of the secondary lining, and the minimum safety factor of the tunnel's secondary lining structure increases from 2.0 without a insulting layer to 4.0 when the insulting layer is set.