Floor heave has been one of the important ground control problems in the underground coal mining industry. However, the mechanisms of floor heave have not been fully understood although some efforts have been made by many researchers. In this research, two mines experiencing floor heave are selected to study the mechanisms of floor heave. By in situ observation, two types of floor heave are identified: Type I floor heave caused by buckling failure of floor, and the Type II floor heave caused by plastic failure and plastic flow of floor material. Based on the observation results, the mechanisms of floor heave are analyzed and the mechanical models for two types of floor heave are established. The model for type I floor heave is based on composite slab theory and the model for type II floor heave is based on foundation theory. Using the models established, the floor heaves in two mines were analyzed and one of them was redesigned. Results show that the floor heaves predicted by the models are quite accurate. The mine has eliminated the floor heave problems after it had been redesigned.
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