Unloading Mechanics and Energy Characteristics of Sandstone under Different Intermediate Principal Stress Conditions

Figure 3

Loading and unloading stress-strain curves under different . (a)  = 5 MPa. (b)  = 11 MPa. (c)  = 17 MPa. (d)  = 20 MPa.

(a)

(b)

(c)

(d)