Modeling Strength of Sandy Gravel

A new method to evaluate static strength and deformation behavior of gravelly soils containing particles too large to be tested with conventional laboratory equipment is presented. This new matrix method is based on the assumption that large particles floating in a matrix of finer‐grained material do not significantly affect the strength and deformation characteristics of the mixture. Therefore, the behavior of a prototype soil containing oversized particles can be modeled by testing the matrix portion alone, provided the model specimen is prepared at the density that exists within the prototype soil away from the oversized particles. A testing program designed to validate the matrix modeling method is described. Results of consolidated‐drained triaxial (CDTX) tests performed on prototype and model specimens are presented. CDTX peak shear strengths for the prototype and model soils are found to be almost identical. Fully softened strengths for the prototype and model specimens vary by no more than 15%. The stress‐strain and the volumetric strain‐axial strain behavior of the prototype and model soils are very similar up to the peak shear stress.