Abstract: The fractures with high temperature formed by heat damage of coal and rock are the main causes to the evolution and spread of the coal fire.The foam cement fluid is a new type material for preventing and controlling the coal and rock fractures with high temperature.The heat resistant property of foam fluid is the important technical parameters.Based on homemade testing system for foam fluid heat insulation performance, the thermal insulation property of foam fluid with different bracket height (2 cm, 7 cm, 12 cm, 17 cm, 22 cm) and injection thickness (20 mm, 40 mm, 60 mm, 80 mm) were tested.It is concluded that with the increase of test time, the cold surface temperature of all the foam fluids increase from 20 mm to 80 mm, however, the slope of temperature rise curve is bigger within the test time of 0-90 s.The distribution of heat insulation temperature is in a curved surface as a whole.Then the relations of thermal insulation temperature, injection thickness and hot surface temperature were fitted.Under the condition of heating, the morphology change of bubble liquid film shows that the foam fluid is unstable at 200 ℃.The effects that heating on drainage rate of liquid film were studied from three aspects including surface tension, viscosity of liquid film substrate and free water content.

Key words: high temperature fracture;sealing;thermal insulation;thermal stability