A combination of field monitoring, Close Range Photogrammetry (CRP) and 3-dimensional numerical modeling is used in an underground potash mine to study the closure rates in the main panel as well as in large underground storage areas. The main interest is to predict the closure rate and total displacement in the storage area where a large stacker is operating. Due to the considerable dimensions of the storage area, conventional methods of monitoring are not feasible. Numerical modeling was selected as a tool to predict the convergence. A 3-dimensional numerical model using FLAC3D computer program was employed. The two-component power law model has been selected to express the creep behavior of potash and surrounding salt formations.There is limited data on the value of n and A parameters in the power creep law. Numerical results are compared with the field measurements in the panels. CRP is being employed as well, which allows measuring the displacement on a cross section between the pillars. This type of analysis provides useful information on both lateral and vertical displacements of the pillars. All structural features, such as clay layers and beddings as well as rock bolts are included in the model.
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