Experimental Analysis of Effect of Sandy Sediments Produced by the Sand-control Projects of Qinghai-Tibet Railway on the Surface Heat Exchange
Sand control project is the main way used for the protection of the Qinghai-Tibet Railway from sand damage.However,sand-control practice will result in sand deposition inevitably.Currently,the effect of sandy sediments on the surface heat exchange is unclear.Therefore,utilizing net radiometer with four components and adopting the methods of synchronization contrast observation and laboratory tests in the test field of Honglianghe River sand-damaging sections of Qinghai-Tibet Railway,the variation of heat exchange was studied after the ground surface was covered with sandy sediments produced by the sand-control projects of Qinghai-Tibet Railway.The study found that after the ground surface was covered with sandy sediments produced by the sand-control projects of Qinghai-Tibet Railway,the surface albedo increased.The annual average albedo on the surface of sandy sediments was 0.05 higher than that of the surface without sandy sediments.The surface upward shortwave radiation increased with the annual average value of the upward shortwave radiant flux density,the daily total value of the annual average and yearly total value of the upward shortwave radiation on the surface of sandy sediments 8.56 W/m2,0.74 MJ,269.99 MJ higher respectively than those of the surface without sandy sediments.The surface net radiation decreased with the annual average value of the net radiant flux density,the daily total value of the annual average and yearly total value of the net radiation on the surface of sandy sediments 12.49 W/m2,1.08 MJ,393.47 MJ lower respectively,compared with those of the surface without sandy sediments.These variations resulted in the reduction of the heat source on the surface of sandy sediments.Further,the heat transmitted to the underground through sediment deposition was reduced due to the weak thermal conductivity of sand layer,which is beneficial to the prevention of permafrost from degradation in the section of sand-control of the railway.
NETL
NSTL
万方数据
维普
