Метод оценки коэффициента формы зерен щебня, применяемого в балластном слое железнодорожного пути

Abstract

A decrease in the strength properties of crushed stone in combination with an increase in its contamination during tonnage operation reduces the load-bearing capacity of the ballast layer and intensification of the accumulation of residual deformations of the track. The strength properties of crushed stone ballast depend on the shape (rolling edges) of crushed stone grains. The paper discusses the theoretical and practical foundations for determining the shape of crushed stone ballast grains. As an indicator characterizing the shape of crushed stone grains, it is proposed to use the grain shape coefficient indicator. The grain shape coefficient refers to the ratio of the actual specific surface of the grain to the specific surface of a perfectly round particle of the same volume. The paper proposes a method for determining the specific surface based on the Kozeni-Karman theory of the flow of a liquid or gas through a granular layer and the equation relating the water permeability of a porous medium to its specific surface. The basic design of the device for the specific surface area of crushed stone ballast grains is presented. The article describes and presents the results of the experiment on calibration of the device, establishes recommended and boundary conditions for its use, as well as the results of the experiment to determine the specific surface in experiments with crushed stone of category II according to GOST 7392-2014 in comparison with an alternative method of measuring the specific surface of crushed stone grains.