Optimisation Study on Crack Resistance of Tunnel Lining Concrete Under High Ground Temperature Environment

In the construction of tunnels in environments with extreme temperatures, excessive temperature differences will lead to the early cracking of concrete lining after pouring, which subsequently affects the safety and durability of the tunnel lining structure. On the basis of the secondary development platform of ABAQUS, this study compiled a series of subroutines for the analysis of the hydration heat release, thermal mechanical coupling and temperature humidity coupling of early-age concrete. Combined with the extended finite element method, the temperature humidity stress multifactor coupling numerical analysis model is established. Subsequently, the early-age cracking mechanism and control measures of tunnel concrete under the high ground temperature of the surrounding rock environment were examined and verified by field-measured data. Studies have shown that 57.8 °C is a critical temperature in theory. When the surrounding rock temperature is lower than this value, the lining can be normally constructed without early cracking. Meanwhile, when the surrounding rock temperature exceeds this value, wall-mounted thermal insulation materials must be used to avoid surface cracking due to the large temperature gradient of lining concrete. The conclusions obtained in this research can provide reference for the design and construction of tunnels under high ground temperature.