Experimental Study on the Thermal Boundary Conditions and Temperature Fields of Duct-ventilated Embankment in Permafrost Regions

摘要: Duct-ventilated embankment is an available cooling method in construction permafrost regions.However,in regard of predicting its long-time effect,there are difficulties boundary condition selection,and lack real test to verify.In this paper,based on observation field experimental embankments Beiluhe Section along the Qinghai-Tibet Railway,the air temperatures ducts and their walls were analyzed simulated.The results indicated that annual higher than environmental by 1.6~1.8 ℃.The temperature difference was less 1.0 ℃ thawing period 2.0 freezing period.Of embankment,the ground at a depth 0.5 m south-facing slope north-facing 3.5~5.5 ℃.Analyzing fields finds ordinary able uplift artificial table also increase around table.Besides,the appears pronounced transverse asymmetry.The ventilated can efficiently cool filled earth underlying permafrost,particularly when installed near original surface.In case middle embankments,the transversely asymmetry not so but still involves with surface.When or below surface,the total zone above ducts.