Abstract:

Tunnel lining concrete is a typical example of thin-walled, large-volume concrete. During construction, the high hydration temperature of pumped concrete and the significant constraints imposed by the surrounding rock often lead to temperature-induced cracking. To explore reasonable temperature control measures, we employed three-dimensional finite element software to analyze the temperature field and thermal stress distribution in a typical tunnel lining section of the Central Yunnan Water Diversion Project. Contact elements were used to model the interactions between the surrounding rock and the lining. Based on on-site monitoring data, we performed a feedback analysis on the surface insulation coefficient of the lining section, which was 16.7 kJ/(m²·h·℃). We investigated how different pouring temperatures, section lengths, seasons, and the autogenous volumetric deformation of concrete affect the thermal stress field of the concrete lining. Our findings indicate that higher pouring temperatures increase thermal stress; specifically, a 4°C rise in pouring temperature reduces the minimum anti-cracking safety factor by 0.30. The maximum stress exceeded 3.5 MPa when concrete was poured during high-temperature seasons. Appropriate segment lengths for the lining structure and micro-expansion concrete can enhance crack resistance. The findings offer valuable insights for temperature control in tunnel lining concrete for the Central Yunnan Water Diversion Project.

Key words: tunnel lining, 3D finite element analysis, temperature stress field, temperature control measures, cracking risk, Central Yunnan Water Diversion Project