Influence of airflow on the frost heaving force in tunnels under windy-thermo-hydro-mechanical coupling
The frost heave of the surrounding rock in cold region tunnels adds additional load to the lining structure,compromising its safety and durability.However,the coupled thermo-hydro-mechanical mechanism under cold airflow in cold region tunnels remains unclear,so studying its influence on the tunnel frost heaving force has important theoretical significance.Based on the overall frost heaving theory of freeze-thaw layers,a multi-field coupling model considering the heat exchange characteristics of airflow and lining,thermo-hydro-mechanical interaction,and orthogonal anisotropy of frost heaving deformation was established.Combined with the field measured freezing depth and frost heaving force values of the Qingshansha Tunnel,the model's reliability was verified using COMSOL Multiphysics finite element software.By using the single factor analysis method,the influence of airflow duration,humidity,velocity,and temperature on the frost heaving force of Qingshansha Tunnel was discussed,and sensitivity evaluations of these four factors were conducted.The results demonstrate that uneven heat transfer leads to different freezing depths and uneven distribution of frost heaving forces;in the freezing depth calculation results,the maximum is at the inverted arch,followed by the arch crown,and the minimum at the arch foot;in the frost heaving force calculation results,the maximum is at the arch foot,followed by the arch crown,and the minimum at the inverted arch.With the increase in airflow duration,humidity,velocity,and the decrease in temperature,the frost heaving forces at the arch foot and arch crown increase,while the frost heaving force at the inverted arch is greatly affected by the stress release of deformation.However,the increase rates of frost heaving forces for the three positions show a trend of arch foot being the largest,arch crown next,and inverted arch the smallest.Controlling the duration of airflow,maintaining dry,low-speed,and non-negative temperature airflow can effectively reduce the frost heaving force.The sensitivity of factors affecting the frost heaving force is in the order of"airflow duration>airflow temperature>airflow velocity>airflow humidity".The research findings offer a theoretical foundation for implementing insulation and anti-freezing strategies for tunnels in cold regions.
万方数据
维普
