Laboratory investigation on cooling effect of sloped crushed-rock revetment in permafrost regions

A series of experiments were done for the cooling effect of sloped crushed-rock revetments with different particle sizes under wind action in this study. The crushed-rock particle sizes include four kinds: 6–8, 14–16, 21–23 and 28–30 cm. The experimental result indicates that, under the windward and leeward conditions, the crushed-rock revetments 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 revetments can be lowered to below 0 °C after two experimental cycles. At windward side, with the increase of particle size, the cooling effect of crushed-rock revetment becomes better when its particle size ranges between 6 and 30 cm; At leeward side, the cooling effect of crushed-rock revetment 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 revetment 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 revetment is far larger than that of the leeward one; and the maximum positive temperature at the bottom of windward crushed-rock revetment in every cycle is far higher than that at the bottom of leeward one; furthermore, the time of its positive temperature is longer, and it will be disadvantageous to the stability of permafrost embankment. At the same time, by analyzing the temperature distributions of the crushed-rock revetments, we find that the cooling mechanism of the leeward side is more complicated than that of the windward side.