Permafrost

frozen soil. While compared with the normal duct-ventilation roadbed, the cooling effect of the
particle improved roadbed in cold seasons is worse, but the thermal shield effect in warm
seasons is better. Considering the annual average ground temperature, it shows that this
measure is better potential effect on the protection of frozen soil. It proves to be an active
measure for the protection of frozen soil.
Key words: permafrost, the particle improved roadbed, temperature-control effect
Laboratory investigation on cooling effect of crushed-rock slope
under wind action in permafrost regions
Mingyi Zhang, Yuanming Lai, Shuangyang Li, Shujuan Zhang
( State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering
Research Institute, Chinese Academy of Sciences, Lanzhou Gansu 730000, China )
Abstract: A series of experiments were constructed for the cooling effect of crushed-rock
slopes with different particle sizes under wind action in this study. The crushed-rock particle
sizes include four kinds: 6~8、14~16、21~23、28~30 cm. The experimental result indicates
that, under the windward and leeward conditions, the crushed-rock slopes with the four particle
sizes all have good cooling effect and can effectively decrease the temperatures of the
underlying soil layers; furthermore, the mean periodic temperatures of soil slope surfaces under
crushed-rock slopes can be lowed down below 0 after two experimental cycles. Under
windward condition, with the increase of particle size, the cooling effect of crushed-rock slope
becomes better when its particle size ranges between 6 and 30 cm; under leeward condition, the
cooling effect of crushed-rock slope with a particle size range of 21~23 cm is best. Besides,
we also find that, under the experimental condition, the periodic range of temperature at the
bottom of crushed-rock slope is mainly dominated by windward/leeward condition, not
crushed-rock particle size; namely, the periodic range of temperature at the bottom of windward
crushed-rock slope is far larger than that of leeward one; and the maximum positive
temperature at the bottom of crushed-rock slope in every cycle under windward condition is far
higher than that under leeward condition, furthermore, the time of the positive temperature is
longer under windward condition, and it will be disadvantageous to the stability of permafrost
embankment. At the same time, by analyzing the temperature distributions of the crushed-rock
slopes, we find that the cooling mechanism of the leeward side is more complicated than that of
windward side.
Key words:cooling effect; crushed-rock slope; windward and leeward conditions; wind action;
particle size
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