Ryszard Mielimąka

The presented research subject involved the assessment of the possibility of mining operations within the area of shaft protection pillar with simultaneous liquidation of the shaft. In such a situation, the basic condition is to avoid damage to shaft lining, which can hinder or even prevent safe liquidation of the shaft by backfilling. The procedure to follow in order to assess the possibility and scope of mining exploitation within the shaft protection pillar is demonstrated on the example of shaft X. The applied assessment method involving the possibility and scope of mining exploitation within the protective pillar of the shaft was based on the forecast of rock mass deformation at the shaft site, which was the basis to calculate vertical stresses in the shaft lining and then to compare them with permissible values. The carried out calculations allowed us to determine the permissible face advance of longwall No. 5 at which no damage to the lining and its equipment would occur, ensuring the planned safe liquidation of the shaft by backfilling.

The article presents the results of geodetic measurements and numerical modeling of mining area deformations in the partial exploitation area of the 712/_1-2 seam at the Marcel Coal Mine. An important element in this exploitation is the limitation of the length of longwalls with cavings to 130 m and 150 m, leaving an unextracted 70 m wide coal solid belt between them. Leaving the belts aimed to reduce deformations of the mining terrain, with relatively limited deposit losses. The numerical modeling of mining terrain deformations was performed using the Fast Lagrangian Analysis of Continua (FLAC) software package based on the finite difference method. The results of the geodetic measurements and computer simulations presented in the article confirm the assumption adopted during the planning stage of this exploitation about the possible significant reduction of mining terrain deformations caused by leaving the unextracted belts of coal solid between successive longwall panels.

The paper presents an example of real subsequent underground hard coal mining (3 longwalls), which caused the formation of a subsidence trough on the surface of the mining area. Surface deformations were covered by systematic leveling measurements along the measurement line "1". For the illustrated example of underground mining, numerical calculations were made using the theory of cellular automata. Calculated data were compared with the results of leveling. The aim of the article was to verify the theoretical assumptions of the model and to demonstrate the practical possibilities of applying the method to assess the subsidence of the mining area.

In this article have been presented the approximation results of average course of mining area subsidence measured at observational line and caused by hard coal exploitation, which was conducted by some hard coal mine in Poland. An approximation has been done with the use of smoothed spline function with value change of smoothing parameter of approximating function. The right value of smoothing parameter has been chosen by the use of least squares method, what means the minimization of differences sum between the measured terrain subsidence and their average values.

This paper presents the method of performing forecast of the influence of exploitation planned in seam 503 by the "Bobrek" Unit of "Bobrek-Piekary" Coal Mine on the Holy Cross Church in Bytom - Miechowice. It contains the analysis of church construction and history of its renovations, geological and mining conditions in the church area as well as deformations it underwent as a result of mining exploitation conducted so far. Forecast of influences of planned exploitation was performed with the use of EDBJ program, a formula for subsidences by J. Białek, applying the best local values of parameters of this formula in the sense of the least-squares method. The analyzes presented herein were used to assess the possibility of conducting planned exploitation in the context of protecting this church.

The mean square approximation of average course of mining area subsidence with the use of a flat spline as a approximating function was conducted to determine an approximate course of curvatures observed on a measuring line set over exploitation run by “Chwałowice” coalmine. The assumed minimising criterion of loss function was referred to the forecast values of vertical ground displacements calculated via Knothe’s formulas. The average courses of inclinations and curvatures of mining area were obtained via the calculation of their values by means of empirical formulas taking into consideration the obtained approximate values of measured subsidence.

The article presents the original results of the study concerning the way of approximation of average course of measured curvatures of mining area. The mean square approximation of average course of mining area subsidence with the use of a flat spline as a approximating function was conducted to determine an approximate course of curvatures observed on a measuring line set over exploitation run by “Chwałowice” coalmine. The assumed minimising criterion of loss function was referred to the forecast values of vertical ground displacements calculated via Bialek’s formulas. The average courses of inclinations and curvatures of mining area were obtained via the calculation of their values by means of empirical formulas taking into consideration the obtained approximate values of measured subsidence. Subsequently, they were compared with the forecast values by Bialek’s formulas and theoretical values obtained on the basis of empirical formulas including subsidence values forecast by Bialek’s formulas. Due to that the determination of errors of the forecast and theoretical distributions of curvatures and estimation of usefulness of the conducted analyses was possible.