Calibration of Barcelona Basic Model parameters for Unsaturated Ankara Clay

This paper deals with the calibration of the Barcelona Basic Model for intact samples of unsaturated Ankara Clay. Ankara Clay is a stiff to very stiff high-plasticity expansive clay that often contains fissures in its intact form. Intact samples were extracted from the premises of Middle East Technical University in Ankara. A comprehensive experimental campaign was carried out in order to determine the hydraulic and mechanical properties of the sample, encompassing saturated and unsaturated triaxial and oedometric compression tests. Soil Water Retention Curve (SWRC) and shrinkage curve were also determined experimentally. Results of the experiments shed light on the strength characteristics of intact Ankara Clay. These results were further used to calibrate the Barcelona Basic Model such that it could model the unsaturated behavior of the sample under compression and shear loadings. Valuable insights were gained regarding the suitability and feasibility of using the Barcelona Basic Model for Ankara Clay and other similar stiff high-plasticity clays. It was concluded that the Barcelona Basic Model cannot accurately model the behavior of stiff high-plasticity expansive clays such as Ankara Clay because it fails to capture the brittle behavior they tend to exhibit at high suctions.