Numerical Analysis of Hydrothermal Coupling Between Railway Abutment and Roadbed in Permafrost Regions
To study the formation mechanism of frost heave and tilt disease on railway bridge abutments in permafrost regions and analyze its deformation law,a finite element model of the bridge abutment subgrade is established to analyze the temperature field characteristics of the subgrade behind the bridge abutment and the frost heave and tilt law of the bridge abutment.Based on the theory of unsaturated soil seepage and heat conduction,the water and heat differential equations of frozen soil are established,and the deformation field is calculated using ice content to achieve the coupling of water and heat fields.By Using COMSOL software,a three-dimensional bridge abutment subgrade water thermal coupling model is developed and verified through indoor freeze-thaw tests.Finally,taking a railway bridge abutment in a permafrost area as an example,this study analyzes the upper limit of permafrost and the inclination of bridge abutment frost heave in the next 30 years for the roadbed behind the abutment.The results indi-cate that in the next 30 years,the upper limit of permafrost on the roadbed after the bridge abutment will continue to decrease,But the continuous input of cold air in the cross section of the bridge abutment has affected the depth of the upper limit of permafrost at various positions along the roadbed.At a distance of 4 m from the bridge abutment,the upper limit of permafrost on the sunny slope of the roadbed will decrease by 0.99 m in the next 30 years and that at the center of the roadbed will decrease by 0.92 m.At a distance of 16 m from the bridge abutment,the upper limit of permafrost on the sunny slope foot of the roadbed will decrease by 1.6 m in the next 30 years and that at the center of the roadbed will de-crease by 1.81 m.In the next 30 years,the roadbed behind the bridge abutment will continue to expe-rience a differential horizontal frost heave,with a cumulative horizontal displacement of 155.6 mm at the top and 23.6 mm at the bottom,resulting in an overall tilt of the bridge abutment.
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