Examination of critical state parameters for sands

Site variability is one of the most challenging aspects of geotechnical site characterisation. This is particularly important for offshore wind developments which are often located where ground conditions are highly variable. Determination of soil parameters for such variable sites generally requires large number of tests on good quality samples. This may not always be practical due to project constraints including difficulty in recovering good quality intact samples for testing (e.g. for sand). Therefore, predictive models based on critical state soil mechanics framework are often pursued considering their potential for predicting soil behaviour for different initial states. This paper investigates available data on different types of sands and proposes a simple approach for estimating the critical state line for sand. The proposed approach is intended for high level assessments of the critical state line for projects where site-specific data are not available. In addition, it is envisaged that the different relationships proposed in this paper may provide a useful guide to optimise/refine a laboratory testing programme. Simplicity and practicality are the key features of the proposed approach.