Study on floor heave course of extraction opening

The development course of the floor heave of extraction opening is studied in this paper. The stress status of floor stratum is changed from three-dimensional stress into two-dimensional stress after the roadway is droved, meanwhile. The floor stratum is separated or fractured because the deformation energy of the strata is released. In the course of extraction, because of the effect of the advancing abutment pressure, the separated rock stratum will be compression-bended and fractured by the second horizontal stress while the roadway sides produce subsidence and horizontal displacement. However, it is important for floor heave that the broken rock produce structure expansion because of peak-residual creep. It is supposed that mechanical character of the floor strata is a main factor leading heave, which the advancing abutment pressure and the deformation of the roadway sides are also relation with it. 8figs.,5refs.