Geotechnical properties of glacial sediments using cone-penetrometer testing

Cone-penetrometer testing (CPT) can greatly improve insights into multi-scale geotechnical and sedimentological variability of glacial sediments. This study uses CPT measurements to address shear strength and soil-behavior type of glacial sediments in Illinois, which include numerous tills, lake sediments and fluvial deposits of the Lake Michigan Lobe. Many similar studies have evaluated glacial sediments using lower-resolution standard-penetration tests or laboratory index tests, but in-situ CPT data are more advantageous because of the continuity of sampling and well-established correlations. We sampled 14 glacial geologic formations from 39 sites in Illinois and characterized geotechnical properties of those formations from regional to site scales. Generally, CPT-based shear strength estimates and soil behavior-type indices track reasonably well with measured soil texture, but occasionally the CPT-based parameters vary with parameters other than texture alone, even within a given geologic formation. This study has important implications for improving the engineering utility of geologic maps, improving CPT correlations, and better understanding the impacts of sedimentology on geotechnical properties and variability.