Renewable Energy, Vol.156, 645-654, 2020
Numerical evaluation for protecting and reinforcing effect of a new designed crushed rock revetment on Qinghai-Tibet Railway
Crushed rock revetment (CRR) has been widely implemented to mitigate the geothermal disturbance from the embankment construction and global warming. The cooling effect and air convective mode of the traditional CRR (TCRR) and a new designed solar-shading CRR (SSCRR) were comparatively studied based on a developed and verified heat and mass transfer model. The results indicate that TCRR used as a protecting measure cannot eliminate the geothermal disturbance in warm permafrost regions, but can preserve the permafrost foundation in cold permafrost regions, while SSCRR can further cool the permafrost foundation. If TCRR is added to reinforce a 10 years operated general embankment, it can only grudgingly keep the thermal disturbed state for about 35 years and 45 years in warm and cold permafrost regions, respectively. SSCRR, by contrast, can refrigerate the operation-disturbed permafrost foundation. Wind-forced dominated convection for TCRR in warm season dissipates the 'cold energy' accumulated in cold season, however, synthetic reaction for SSCRR with a longer and higher efficiency cooling process in cold season and better heat insulating effect in warm season conducts a superior cooling effect. These results provide a basis for the optimization of cold energy utilization systems for the embankments in the degenerating permafrost regions. (C) 2020 Elsevier Ltd. All rights reserved.