Nonlinear Creep Behavior and Viscoelastic-Plastic Constitutive Model of Rock-Concrete Composite Mass

Figure 7

Fitting curves of step loading rate and initial creep rate of composite specimens under different confining pressures. (a) Confining pressure 0 MPa. (b) Confining pressure 7 MPa. (c) Confining pressure 15 MPa. (d) Confining pressure 22 MPa.

(a)

(b)

(c)

(d)