Abstract
In order to obtain the analytical solution of the plastic area boundary of circular laneway surrounding rock in nonuniform stress field, we studied the evolution of the plastic area shapes of the circular laneway surrounding rock from circular to elliptical and derived the analytical solutions of the boundary radii in the elliptical shape. The results show that (1) with the increase of the confining pressure ratio from 1, the major axis radius of the plastic area increases gradually, the minor axis radius decreases gradually, and the shape of the plastic area gradually evolves from circular to elliptical; (2) on the basis of the Mohr–Coulomb strength criterion, the analytical expressions of major axis and minor axis radii of the elliptical plastic area are derived, and the elliptic equation of the plastic area boundary of circular laneway in nonuniform stress field is established; and (3) the confining pressure ratio is the key factor affecting the shape of the plastic area. When the confining pressure ratio is less than 1.6, the plastic area of the circular laneway surrounding rock is elliptical, and the elliptic boundary equation is applicable. When the confining pressure ratio is greater than 1.6, the plastic area is butterfly shaped, and the elliptic boundary equation is no longer applicable.
Highlights
In underground mining, the laneway passes through the complex geological environment, and roof fall, floor heave, and other laneway disasters have been a major threat to the safety production of coal mines [1,2,3]
The research of the uniform confining pressure model is more mature, and the plastic circle radius calculated by the Fenner and Kastner formulas has been widely used in theory and practice [7, 8]
On the elastic-plastic analysis of laneway surrounding rock in nonuniform stress field, Yu et al put forward the implicit equation of the circular laneway plastic area boundary [12]
Summary
The laneway passes through the complex geological environment, and roof fall, floor heave, and other laneway disasters have been a major threat to the safety production of coal mines [1,2,3]. In the actual underground environment, the stress field around the laneway is complex, especially affected by the tectonic stress and mining stress, and the stress field is often nonuniform [9, 10] At this time, the results obtained by the Fenner and Kastner formulas deviate greatly from the actual situation [11]. On the elastic-plastic analysis of laneway surrounding rock in nonuniform stress field, Yu et al put forward the implicit equation of the circular laneway plastic area boundary [12]. After that, it has been further developed [13]. We studied the evolution of the circular laneway plastic area shapes from circular to elliptical and derived the analytical solutions of the boundary radii in the elliptical shape
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