Reconciling static and dynamic elastic properties of Opalinus Clay at multiple scales

Previous data records have indicated that static Young's moduli of Opalinus Clay constrained in undrained laboratory tests typically need to be scaled by a factor of two to four to match dynamic values. Such apparent discrepancy is unsatisfactory for site appraisal when building a mechanical model from exploration data. An Opalinus Clay core was sourced at the Mont Terri rock laboratory for core tests investigating the frequency dependency of dynamic elastic properties and the strain-dependency of static elastic properties. The laboratory tests were complemented by static and dynamic in situ measurements in the boreholes used to source the cores for laboratory tests. Static and dynamic measurements of Opalinus Clay core were conducted under controlled stress conditions. This study reconciles the static and dynamic elastic properties of the Opalinus Clay at multiple scales. There is consistency between static and dynamic moduli when frequency dependency in the dynamic measurements (dispersion) and strain dependency in the static measurements is taken into account