Title Cooling effects study on ventilated embankments under the influence of the temperature differences between the sunny slopes and the shady slopes
Author Zhang Kun; Li Dongqing; Niu Fujun; Mu Yanhu
Author Affil Zhang Kun, Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China
Source Cold Regions Science and Technology, 65(2), p.226-233, . Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0165- 232X
Publication Date Feb. 2011
Notes In English. 45 refs. GeoRef Acc. No: 309493
Index Terms climatic change; construction materials; degradation; embankments; global change; global warming; heat transfer; mass transfer; mathematical models; permafrost; permafrost heat transfer; permafrost mass transfer; railroads; slopes; soils; soil temperature; structures; temperature; China-- Qinghai-Tibet Railway; Asia; Beiluhe test site; China; climate change; crushed stone; Far East; low temperature; numerical models; permafrost table; Qinghai-Tibet Railway; three-dimensional models; ventilated ducts
Abstract Based on theories of heat and mass transfer, three-dimensional theoretical and numerical models were presented to analyze the temperature characteristics of embankments in permafrost regions. Conditions of air convective within crushed rock layer and the background of the climate warming in the future were considered. In addition, temperature differences between the sunny and shady slopes of embankments, as well as the uneven distribution of air temperatures inside the ventilated duct were also considered in the models. Cooling effects and temperature field characteristics of three kinds of embankments were analyzed and compared. Results of traditional embankment indicated that there were significant differences in permafrost tables between the sunny and shady slopes, and the underlying permafrost was in serious degradation. A large asymmetric 0C melting bulb was formed in and beneath the embankment over winter time. The analysis indicated that the duct- ventilated embankment could lower the temperature of underlying permafrost, and elevate the permafrost table under the embankment. The duct-ventilated embankment could also adjust the differences of permafrost tables, and improve the asymmetry of the temperature fields between the sunny and shady slopes. Due to climate warming, however, a 0C melting bulb still developed at the sunny slope foot of the duct- ventilated embankment. To prevent the 0C melting bulb from occurring, a closed crushed rock revetment was applied on the sunny slope, and the results indicated that the cooling effect of duct-ventilated embankment with the closed crushed rock revetment was better than that without the closed crushed rock revetment. Soils in and beneath the duct- ventilated embankment with closed crushed rock revetment could refreeze completely over winter time and this kind of embankment could also effectively adjust the differences of permafrost tables between the sunny and shady slopes.
URL http://hdl.handle.net/10.1016/j.coldregions.2010.08.005
Publication Type journal article
Record ID 65006614