ABSTRACT
The episodic movement of deep-seated rockslides is often associated with seasonal variations in precipitation and groundwater recharge. Acceleration and deceleration phases are often observed, however, it is not always clear why certain acceleration phases reach alarming levels without a clear trigger (i.e., in the absence of an exceptional precipitation event). This introduces significant uncertainty in the interpretation of displacement monitoring data for early warning, which in turn, is further hampered by the complexity of the underlying rock slope failure processes involved. Numerous examples exist where the interpretation of early warning data without a clear understanding of the underlying mechanisms has led to variable and generally unreliable forecasts. This paper reviews recent research investigating the influence of non-persistent discontinuities, intact rock bridges, brittle fracturing, and internal shearing on the progressive failure of deep-seated rockslides. These mechanisms are then linked to the concept of rock slope fatigue using coupled hydro-mechanical distinct-element modeling to explain the intermittent behavior observed in deep-seated rockslides. Consideration is also given to the influence of seismic fatigue over longer time intervals. Seismic fatigue represents a low repeat frequency but large amplitude damage event, whereas hydromechanical fatigue occurs at a higher repeat frequency but represents a smaller amplitude damage event. When calibrated against slope monitoring data, the consideration of fatigue and progressive failure in numerical analyses offer a means to better support early warning forecasting and improve rockslide hazard management.
