A Study on Ground Temperature Control Method of Hollow Concrete Brick Layer

Active cooling roadbed employed brick-stone layer in permafrost regions is an important engineering measure,it is one of the important elements of application research of frozen soil engineering to study cooling effect and heat convection process in block-stone layer.Based on convection heat transfer mechanism,influence factors of cooling effect and heat convection process,a new hollow concrete brick embankment is suggested for Qinghai-Tibet Expressway.The heat convection process,temperature characteristic and influence factors of cooling effect in hollow concrete brick layer are studied in detail by means of model experiment in lab,and employed high-precision macro wind-speed detector,the relationship between the natural convection and temperature characteristics are got for the first time,and existence of convection heat transfer is confirmed.Research results indicate that the asymmetry of temperature fluctuation result from different heat transfer process and intensity,the reason of cooling effect is convection heat transfer;the temperature difference is driving force of natural convection,duration and strength of which influence directly the cooling effect of the hollow concrete brick layer;the cooling effect of the hollow concrete brick is superior,and the vertical stacking and large size with smooth convective channels are better choices,which will extend obviously heat convection time.The experimental research results have a great guide significance for further understanding of cooling mechanism,improvement of this measure,as well as for effective application of Qinghai-Tibet Expressway in permafrost regions.