The paper presents results of the approximation of land settlement in relation to the following: the Knothe- Budryk theory and the Chudek-Stefański theory concerning the influence of underground mining on the surface and rock mass. This is determined by the integral formula and was approximated to an algebraic form in such a way that it would not be necessary to use integral calculus, while taking into account the average geomechanical values of the rock mass. Empirical data obtained from 34 types of rocks collected from 16 boreholes of the same rock massif made it possible to create a correlation between the main impacts range and the softening coefficient, the immediate compressive strength and the average volumetric weight of the rock mass. The obtained mathematical equations make it possible to calculate the depressions of the land surface, based on the known geometry of excavations and their depths as well as the parameters of the mentioned rock mass. The results obtained from the integral formulas and the approximating formulas are compared. The presented solutions are used in modelling land surface deformation as a result of underground exploitation of deposits resulting from the need to conduct analyses of construction in mining areas, without the need to use calculus.