Calculation of parameters of the protection means for roadway districts in which cement-mineral mixtures are used

Abstract

The method for calculating parameters of the cast and packed protective-insulating walls was improved. The method is distinguished by the combined accounting of physical and technical properties of cement-mineral mixture used in the construction of the wall and the intensity of stress changes in the hardening concrete depending on the mining, geological and technological conditions of the roadway functioning. The following factors are taken into account when calculating the change in loads on the protection means of the roadway district over time: weighted average compressive strength of the rock layers in the roadway roof and floor; category of cavability of the coal seam roof; step of the first and subsequent roof falls; rate of longwall face advancing. To substantiate the correspondence of the mixture physical and technical properties (the intensity of concrete hardening over time) to the change in loads on the protection means of roadway, the values of the limit strength of concrete for uniaxial compression, obtained according to standard tests in laboratory conditions, are used. In order to take into account mine conditions for the construction and functioning of the protective-insulating walls, dimensionless coefficients of influence of the following factors were introduced into the method for calculating their parameters: the wall structure; irregularities of relief of the underworked and overworked rocks pressing on the wall; chemical aggressiveness of mine water, which is used to dissolve the mixture. For the purpose of further controlling condition of supports and protection means in the belt roadway No. 166 of the production enterprise Lisova Mine of the state enterprise Lvivvugillya and adjusting parameters of the protective-insulating wall, a method of mine experimental research is proposed. The method provides for complex studies of the mining condition at all stages of mining operations - during roadway driving, in zone of influence of the longwall bearing pressure, as well as in zones of intense and constant displacements behind the longwall. The displacement of the roadway contour and the change of loads on the means of its protection depending on the location of the longwall face and the speed of its advance are subject to measurement. The criterion for assessing condition of the protective-insulating wall is its relative vertical deformation over time. The results of the calculation of rational parameters of the protection means in the belt roadway No. 166 (width of the berm and packed wall) with the specified physical and technical properties of the cement-mineral mixture are presented. Based on them, scientific and technical recommendations were developed for support setting and protection of this roadway.