Temperature field spatio-temporal law and frozen-depth calculation of a tunnel in a seasonally frozen region

Abstract

The freezing-thawing process in seasonally frozen regions may cause damage to underground structures, especially tunnels. The temperature field and frozen depth can provide reference for tunnel frost damage treatment. Based on the Banshiling tunnel in Northeast China, the spatio-temporal distribution of the tunnel temperature field was revealed using a self-designed intelligent monitoring system. Combined with the temperature field characteristics, a modified formula for predicting frozen depth was established considering the unfrozen water content. Also, the rationality of the modified formula was verified using an example. The calculation error of the modified formula is 1.23% to 15.63%, which is highly consistent with the observed value. Comparing the spatio-temporal distribution of temperature field and frozen depth, they have high consistency. And both them are approximately symmetrically distributed along the longitudinal direction of the tunnel: the lower the temperature, the greater the frozen depth, and the smaller the longitudinal variation along the tunnel. The sensitivity of frozen depth to geographical factors and parameter factors was explored to clarify the influence of different factors on frozen depth. The results show that the sensitivity of the frozen depth to latitude is much greater than that to altitude, and the sensitivity of the frozen depth to different calculation parameters is in the order of mean annual temperature, initial ground temperature, water content, annual temperature amplitude, and thermal conductivity.