Transient Pore Pressures in LOPs


In conventional stability analyses, the strength properties of the rock mass or shear strength of a rupture surface on which sliding can occur are assumed to be constant over time. Failure is then explained through the influence of a triggering event, for example a heavy rainfall event, which causes disequilibrium between the resisting and driving forces along the sliding surface relative to the constant strength parameters. However, this does not properly explain the temporal nature of deep-seated rock slope failures. This project aims to investigate and answer the following focusing questions:

  • What are the controls on, and the effect of, transient pore pressure responses on pit slope stability over time? Do these contribute to strength degradation and progressive failure?
  • What modelling approaches best reproduce observed hydro-mechanical behaviour in large open pit slopes (building on the LOP II Effective Stress study), with aim to validate the methodologies required to predict the evolution of spatial-temporal responses to cyclical transient pore pressure changes?
  • Can a hybrid extensional-shear constitutive model (in a continuum-framework), or hybrid brittle fracture model (in a discontinuum framework) better model the spatial-temporal evolution of progressive failure and staged pit slope failures (e.g., active/passive blocks) in response to cyclical transient pore pressure changes?