Express-Method for Determination of Rock Heaving Parameters

Abstract

The problem of determining the contours of the area in which rock heaving occurs is important in the design of underground excavations. The solution of such problems is usually performed either in an elastic-plastic formulation using numerical methods, or using semi-empirical methods, which, as a rule, form the basis of regulatory documents. When writing this article, an attempt was made to use the approach described in work Determining the parameters of a natural arch while forming support load of a horizontal roadways to find answers to such questions: is it possible under these conditions to heave rock at all; what are the outlines of the heaving area.
Theoretical studies of geomechanical processes occurring in the vicinity of horizontal excavations using analytical and numerical mathematical methods. Analysis and generalization of the results of theoretical studies. Simple analytical dependencies are obtained that allow calculating the boundary of the base area in which rock heaving occurs and the stability coefficient of this area. As a stability coefficient, it is proposed to use the ratio of the projection onto the vertical axis of the forces holding the heaving rock mass to the projection of the forces that shift this mass. It has been established for the first time that the maximum depth under the excavation, where the heaving of the rock occurs, is directly proportional to its strength, calculated using the strength criterion of O. Shashenko, multiplied by half the width of the excavation and inversely proportional to the specific adhesion of the rock. It was also established for the first time that the coefficient of rock stability in the area of its heaving is directly proportional to its strength, calculated using the strength criterion of O. Shashenko, and back - to rock pressure at the calculated depth. The results obtained in the course of this work make it possible, using mathematical methods, to perform: forecast of the stability of horizontal excavations in the area of rock heaving, taking into account the depth of the excavation, its geometric dimensions, specific gravity and strength properties of the rock; the boundaries of the rock heaving area, taking into account the depth of the excavation, its geometric dimensions, specific gravity and strength properties of the rock.