The effect of stress path on the dilatation angle of soils

Modelling the horizontal displacements in subsoil is essential in many geotechnicaldesign situations. Especially dilatation angle should be correctly defined in order to ensureaccurate modelling. Hence, this paper studies how the direction of stress path affects thedilatation angle of various soils. The study utilizes numerous anisotropically consolidated anddrained compression triaxial tests, and the samples represent normally consolidated soft clay,stiff over-consolidated silt and dry sand. The plastic potential function is derived based on thetriaxial test results, using stress values in which the dilatation angle is identical to the directionof stress path. The shape of potential function is assumed to be similar to the yield function, butwith different parameters (non-associated modelling of strains). Finally, deformations arecalculated by using the concept of potential energy, which is a second order function in meaneffective stress - deviatoric stress -space. Simulated values are then compared to triaxial testmeasurements, and the agreement between values is found to be rather good.