Analysis of the stress state at the contours of underground horizontal workings of elliptical cross-section shape subjected to all-round uniform pressure

Abstract

The results of the research to determine the stress state on the contours of underground horizontal excavations, the cross-section of which has the form of an ellipse of any size and shape are presented. When changing the intensity of tensile uniform pressure applied to the points of elliptical shape cross-section excavation contours, the given values of excavation depths, ellipse parameters and rock side spreading coefficient values, the areas of the contours with tensile and compressive stresses are identified. If the depths of workings of the considered form of cross-section change, the areas where tensile and compressive stresses act at given values of the intensity of tensile uniform pressure applied to the points of working's contours, ellipse parameters and values of the coefficient of rock lateral spreading are highlighted. The graphical images of the normal tangential stresses, acting on the contours of the considered workings are given. The ranges of intensity of the tensile uniform pressure, at which, depending on the depth of excavation, values of ellipse parameters and the coefficient of rock lateral spread, tensile and (or) compressive stresses act in the points of excavation contours have been determined. The given relations and results can be applied to calculate the values of the permissible values of all-round uniform pressure in the points of the workings contours and to determine the permissible depths of their embedding. As a criterion for determining the values of these values, the condition of absente on the contours of excavations of points in which the normal tangential stresses exceed the limits of tensile and compression strength of the rock can be accepted.