A Creep Damage Constitutive Model for a Rock Mass with Nonpersistent Joints under Uniaxial Compression

Figure 1

The typical creep curve of the rock element. It has four typical stages: (1) The instantaneous elastic strain (OA): when the stress is applied on the rock element, an instantaneous elastic strain ε₀ is generated immediately, which is often modeled by Hooke’s law. (2) The transient creep strain (AB): the strain increases with time, but the strain rate gradually decreases to a constant. (3) The steady creep strain (BC): the strain rate nearly keeps constant, and the strain increases linearly with time. (4) The accelerating creep strain (CD): the strain rate increases rapidly with time and finally followed by the failure of the rock element.