Implications of groundwater behaviour on the geomechanics of rock slope stability

Groundwater interaction is recognised as one of the key variables influencing slope design and management and is particularly significant in weaker rock masses. Understanding groundwater and pore pressure behaviour in rock masses is generally based on accepted theory related to flow through porous granular media. The presence of discontinuous geological structures within rock masses distorts the accepted hydraulic behaviour and the profile and aperture variability presents the designer with a complex challenge.

The paper adopts a geotechnical perspective and provides a review of our understanding of the interaction of groundwater with rock masses, including the accepted mechanics of water flow through granular and fractured media. The discussion considers how this behaviour can be expected to be locally modified and what implications this may have for slope stability. The discussion references observations as well as laboratory testing and physical measurements with consideration of the role of tortuous laminar flow and capillarity.