Measuring strength and consolidation properties in lacustrine clay using piezocone and self-boring pressuremeter tests

Abstract

As a result of the growing population in Switzerland, new infrastructure is increasingly founded in areas of extremely soft clays, which are challenging to build on. Reliable characterization of such sediments is, therefore, essential to facilitate efficient and economical designs. For various reasons, it is often beneficial to measure soil properties in situ, using probes like the piezocone or self-boring pressuremeter. The main objective of this study was to explore the key differences of these two site investigation techniques in terms of measuring undrained strength and consolidation characteristics in varved lacustrine clay. Experimental data from a field-testing campaign carried out in Switzerland demonstrate that both probes yield comparable results. The quality of the predictions was further assessed by comparing the field measurements to results from laboratory tests and existing empirical relationships. Additionally, a new method based on Monte Carlo simulations was presented, to provide context to the disparity between the consolidation coefficients estimated in the field ( ch) and laboratory ( cv), and to aid prediction of field values of ch from laboratory measurements.