Study on the influence of lining structure type on temperature and stress field of high rock temperature tunnel

Aiming at the problem that the thermal field evolution law of sandwich lining in high rock temperature tunnel is unknown and the stability research is insufficient, a three-dimensional transient composite and sandwich lining numerical model is established to compare the evolution process of temperature field and stress field during construction-operation period. The thermal insulation effect of sandwich lining is revealed and the rationality is verified by experiments. The findings demonstrate that in comparison with the composite lining configuration, The layer of heat insulation in the sandwich lining configuration effectively prevents heat from transferring from the rock to the secondary lining. The stress of the secondary lining is also significantly lower than that of the initial support. This indicates that the sandwich lining structure can significantly reduce the thermal stress experienced by the secondary lining, thereby improving its structural durability. The thermal insulation layer reduces the transfer of high external temperatures to the lining structure, but it causes significant heat accumulation in the initial support, leading to increased stress. This paper's findings will provide an analysis of high-temperature tunnel lining structures, helping to prevent and control tunnel heat damage and improve project safety and reliability.