Експериментальні дослідження деформаційних характеристик закладальних масивів

Abstract

Purpose of work is to determine the deformation characteristics of the backfill massifs used to support the side rocks behind the working face in the cut area of a coal mine. To achieve this goal, laboratory studies were carried out on samples of crushed rock of different particle-size composition, which were subjected to uniaxial compression in a steel cylinder (virgin compression) and in a special bag (with the possibility of lateral expansion of the filling material). As a result of the studies performed, it was found that the relative deformation of a compacting body from crushed rock during virgin compression is less than the relative deformation of the same body when lateral expansion of the filling material is possible. It has been experimentally proven that with the possibility of lateral expansion of the filling material, the values of the relative deformation change according to a linear relationship, when with an increase in the bulk density of crushed rock after uniaxial compression, a decrease in the vertical size of the compacting body is recorded. For crushed rock of heterogeneous particle-size composition, at maximum values of the compaction coefficient and virgin compression, the vertical size of the compacting body is 36 % less than in the case of uniaxial compression of the filling material with the possibility of lateral expansion of the crushed rock. Moreover, the smaller the fraction of crushed rock, the greater the recorded difference. The change in the cubic capacity of the compacting body occurs as a result of repackaging of particles of different sizes in the total volume of the filling material and the spread of crushed rock along the plane under the action of a compressive load. The value of Poisson’s ratio under conditions of uniaxial compression of crushed rock with the possibility of lateral expansion of the compacting body changes according to a parabolic dependence and reaches minimum values in the presence of inhomogeneous (in particle size) crushed rock in the filling material. The maximum values of the investigated coefficient are provided after compression of the initial material of coarse or fine fractions, which initially compose the filling mass. Ensuring the stability of side rocks, the operational state of mine workings in the excavation areas of a coal mine and preventing subsidence of the earth's surface are achieved after the construction of a filling mass in the worked-out space, consisting of inhomogeneous (in size) pieces of crushed rock, which has compression characteristics. Therefore, the requirements for the properties of filling arrays are determined in accordance with their purpose.