The traffic-induced cyclic stresses on the road base and subbase courses are usually in three-dimensional stress state, while so far most laboratory studies have focused on the deformation behavior of base and subbase layers in axisymmetric stress state. This study investigates the three-dimensional resilient behavior of coarse granular base and subbase materials based on a true triaxial apparatus. The factors of effective confining pressure, [Formula: see text], amplitude of cyclic shear stress, qampl, coefficient of cyclic intermediate principal stress, bcyc, and fines content are involved. Test results indicate that the increase of either [Formula: see text] or qampl leads to a nonlinear growth of resilient modulus with a decreasing growth rate. bcyc, which is proposed to represent the coupling of cyclic major and intermediate principal stresses, is found to have a promotion effect on the resilient stiffness, and the promotion effect tends to be enhanced by the increase of qampl. A modified model is established to predict the resilient modulus of coarse granular materials in three-dimensional stress state. There appears to exist a critical value of fines content, at which the variation trend of resilient modulus is changed from increasing to decreasing, and the critical fines content is related to both [Formula: see text] and bcyc.
New three-dimensional plastic flows corresponding to a homogeneous stress state
