Assessment of rock mass decay in artificial slopes

This research investigates the decay of rock masses underlying slopes, and seeks to quantify the relations of such decay with time and geotechnical parameters of the slope and rock mass. Decay can greatly affect the geotechnical properties of rocks within engineering timescales, and may induce a rapid change in mass strength, from initial rock-like properties to soil-like properties in a weathered state., as well as a notable decrease of slope stability. Several rock types are known to have a high susceptibility to such decay within engineering timescales, most notably mudstones and gypsum-bearing formations. A close relationship has been found between weathering intensity rates, the slope orientation and the prevailing wind directions during rainfall events, with a notable influence of damage to the rock mass by the applied excavation method. The exact relation differs from one geotechnical unit to another depending on the principal weathering processes that act on each individual unit. These relations can be used to predict weathering intensity rates and therefore also the weathering degree as a function of time. With the use of a probabilistic slope stability assessment method, predictions for future slope stability can also be made.