Abstract: To ensure the construction progress and quality of open-cut tunnels while preventing temperature-induced cracks in the lining structure after mold removal, a case study is conducted on a reserved high-speed railway project at Xianyang Airport in Xi′an, China. The simulation involves the tunnel lining structure with the largest cross-sectional size, employing finite element simulation and field tests. The analysis considers the locations and variation patterns of temperature cracks and maximum principal stress in the open-cut tunnel lining structure. The comprehensive assessment considers the time variability of the construction environment and the lining concrete. The simulation results are then compared with the concrete strengths at different ages, indicating that temperature cracks in the tunnel lining structure do not occur within 48 h after concrete casting. A calculation formula for the mold removal time of tunnel lining structures of different sizes is developed based on the simulation results. Subsequently, timevarying reliability theory is introduced to validate the rationality of mold removal time. The load effect and statistical characteristics of the most unfavorable section of the lining structure are determined through a combination of uniform design and response surface methods. These parameters are then incorporated into the limit state equation, and the reliability of the most unfavorable section of the lining structure 48 h after mold removal is calculated using the MATLAB program. The calculation employs the firstorder secondorder moment method. The resulting reliability value is 6.61, surpassing the standard specified in the guidelines. This outcome demonstrates the feasibility of the proposed mold removal time.

Key words: open-cut tunnel, lining mold removal, reliability, response surface method, uniform design