Determination of Approximation Parameters of an Average Graph of Mining Terrain Subsidence Caused by an Exploitation of Hard Coal

Article presents a method of approximation of average graphs of mining terrain subsidence caused by an exploitation of the 338/2 hard coal seam in the south part of Poland. Subsidence, which are result of a hard coal extraction by the use of four longwalls, were observed on the points of a measuring line located perpendicularly to the excavations runs. Presented method is based on division of a vertical profile of subsidence trough into the parts and making approximations in each segment separately. The polynomials were used as an approximating function. An appropriate polynomial order and number of its fragments on the basis of a minimization of variability coefficient of random dispersion of measured subsidence have been chosen.