Abstract
This paper presents a recommended practice for the use of strength anisotropy in stability calculations. The recommendations are based on laboratory data from high quality block samples collected by NGI from more than 20 sites. The strength anisotropy was correlated against natural water content, OCR, sensitivity, plasticity index and clay contents. Despite some scatter in data, the paper presents correlations to estimate strength anisotropy for Norwegian clays. A benchmark stability calculation has been done to illustrate the overall impact of various anisotropy factors on the factor of safety.