青藏高原多年冻土区碎石护坡降温作用及效果分析

Cooling Effect of Crushed Rock Revetment in Permafrost Regions

基于青藏高原北麓河多年冻土区碎石护坡路基与普通路基温度监测资料分析,结果表明:碎石层的铺设具有减小坡面年平均温度及坡面温度年较差的作用;与普通路基相比,碎石护坡在暖季主要起到隔热作用,但在冷季主要存在不利于路基散热的弊病.从路基人为冻土上限抬升状况、温度降低程度和路基变形量的差异来看,碎石护坡路基较普通路基有利于冻土路基的热稳定性.但碎石护坡调节路基内部温度场是一个长期过程,即坡面温度对多年冻土温度的影响具有滞后性,若作为青藏铁路多年冻土区补强措施使用时应慎重.

During the year of 2003--2005, an experimental embankment was constructed in Beiluhe of the Tibetan Plateau, using the fill material of coarse （7--12 cm） and poorly graded crushed rock on the slopes of embankment on the permafrost foundation with thick ground ice, which should be called the crushed rock revetment embankment （CRRE）. The highly permeable CRRE was designed to test the cooling effect of CRRE as com- pared with conventional embankment. By means of thermistor sensors, ground temperatures in the test sections were monitored. Analyzing the ground temperature data measured in the boreholes within the CRRE and conventional embankments, it is found that crushed rock can effectively reduce annual mean temperature and annual range of temperature on slope surfaces. Comparing with the conventional embankment, one can see that the crushed rock revetment has the effect of heat insulation in summer but is disadvantageous to heat losing in winter. According to the rising of artificial permafrost table and the decreasing of ground temperature range and difference of deformation, the heat stability of CRRE＇is more than that of the conventional embankment. It will be a long term process for crushed rock revetment to adjust the interior temperature field, so it should be cautious when using the measure in the Qinghai-Tibet Rail- way.