Stiffness of granular soil from field performance

Over the past decade a great deal of laboratory and in situ test results have been collected, allow ing us a better understanding of the stress-strain and strength behaviour of granular soils . Despite the improved knowledge of the main factors affecting the behaviour of these soils and the usefulness of rational methods, empirical approaches are stilI generally preferred in engineering practice. Due to the difficulties of sampling cohesionless materials and to the effects of their disturbance, these empirical approaches rely on correlations between observed foundation settlements and some parameters from in situ tests, such as the plate load test (Terzaghi & Peck, 1967), the standard penetration test (Meyerhof, 1965), the cone resistance test (De Beer, 1967; Schmertmann, 1970) the pressurementer test (Menard, 1971) and the dilatometer test (Leonards & Frost, 1988). The objective of this study is to re-examine the results of over 200 cases published by Burland & Burbidge (1985) in order to find out whether a consistent picture can be obtained to evaluate an operational stiffness for a continuum mechanics approach.