Elliptic Equation of Plastic Area Boundary around the Circular Laneway in Nonuniform Stress Field

<div>Evolution of the plastic area shape with confining pressure ratio (<i>a</i> = 2.5 m; <i>C</i> = 5 MPa; <i>φ</i> = 25°; <i>P</i><sub><i>3</i></sub> = 20 MPa). (a) Elliptical shape. (b) Butterfly shape.</div>

Shock and Vibration

fig11

Figure 11

Figure 11: Elliptic Equation of Plastic Area Boundary around the Circular Laneway in Nonuniform Stress Field 