Abstract: Through the indoor model experiments， the response laws of the moisture-heat migration and permeability of compacted clay were studied under the temperature gradient. The results demonstrated that: the heat transmitted relatively faster at the bottom of clay column than the upper of clay column; the rise of the temperature underwent an obvious delay with the increase of the distance from the heat source; the heat at the bottom facilitated the occurrence of the temperature gradient inside the compacted clay column， which further prompted the moisture migration from the bottom to the top and caused the quick loss of water; with the continuous heating， the temperature gradient inside the compacted clay column underwent a gradual decline， the rate of moisture migration reduced and the moisture content decreased very slowly and tended to be stable. Under the continuous influence of the heat source， the cracking degree of the upper surface was significantly larger than that of the bottom and it was proved to be feasible to test the cracking depth using a tracer. The temperature gradient raised the permeability coefficient of compacted clay to varying degrees. Moreover， the permeability coefficient at both ends of the clay column rose quickly， followed by that in the middle of the clay column.

Key words: compacted clay, temperature gradient, moisture-heat migration, crack, permeability coefficient