Temperature variation and distribution in underground sidewall: On-site monitoring and finite simulation

Sidewall is the main structure with the highest crack risk in underground engineering, and temperature deformation is an essential factor leading to cracking. Quantitative study on temperature variation and temperature gradient is the basis of temperature deformation research. However, there are few related research reports. This paper aims to quantitatively study the effect of thickness, demolding time, and construction season on the sidewall's temperature variation and temperature gradient. Sensors were installed on-site to collect temperature data, and a finite element model of the sidewall was established to analyze the temperature change process. The temperature variation and distribution under different conditions were analyzed by changing the simulation parameters. Results show that heat is mainly lost in the thickness direction and temperature gradient variations from outside to inside. After demolding, sidewall's surface temperature gradient will suddenly increase, and the cracking risk will be the highest. Sidewall's surface temperature gradient is the largest during construction in winter. Simultaneously, mitigation measures were put forward to reduce the risk of temperature deformation and cracking. The research results can provide a reference value for engineering practice.