Time Function and Prediction of Progressive Surface Movements and Deforma-tions

Three types of time functions, one-parameter Knothe's model, two-parameter Sroka-Schober's time function and Kowalsk's generalized time function, were introduced and their relationships were analyzed. Based on the Knothe time function, the progressive prediction of surface subsidence due to underground mining was established, and the factor of proportionality describing the influence of geological and mining conditions was determined when there was no measured data in practice. A method of periodic pressure distance to divide the total working face into certain elements considering the mining rate or mining duration was proposed. This approach made the calculation of deformation process in time possible from the set-up entry mining to deadline whether the mining rate changed or not. The experiential formula of the ratio of progressive to final maximum deformation values was obtained with respect to different mining rates and different time factors. The result indicates that this method is effective and easy to apply for analysis in practice compared with 1176 E measured data.