A refined approach to barcelona basic model: Experimental evidence and parametric performance

The Barcelona Basic Model is one of the most popular elasto-plastic, critical state based frameworks postulated to date for unsaturated soils. In the last two decades, the model has been the subject of increasingly sophisticated enhancements, mainly from a theoretical standpoint. However, additional experimental evidence and calibration data, for a wider variety of soil materials, are still needed to conclusively substantiate its validation, and more experience is to be gained through parametric investigations of the original BBM formulation in its simplest form. This paper introduces a slightly refined approach to the original BBM formulation in light of significant experimental evidence of a non-linear Apparent Tensile Strength locus in the p:s plane. Results from a series of suction-controlled tests, conducted in a newly developed true triaxial apparatus on compacted clayey sand specimens, were used to calibrate and validate the refined approach, which is referred to as the Refined Barcelona Basic Model. A full assessment of the parametric performance of the Apparent Tensile Strength locus is included. RBBM predictions of unsaturated soil response from suction-controlled conventional triaxial compression tests show a noticeable improvement over those from the original BBM formulation.