Quantification of weathering

Weathering and especially future weathering after construction of a slope is a main cause for failure of a slope duringitsengineering life-time. In the course of developing a rock mass classification system for slope stability, large quantities of data have been collected for quantification of past and future weathering influences on rock mass geotechnical parameters. This research resulted in the determination of reduction values related to the degrees of rock mass weathering as described by the British Standard, that give the reduction of a geotechnical rock mass parameter if the degreeof weathering increases. The large quantity of data allowed for a statistical analysis that assesses the reliability of the valuesfound for the reduction values. These reduction factors are developed in the context of a slope classification system, however, there is no reason that these reduction factors are not valid for other engineering projects in or on rock masses.