Effects of Cyclic Intermediate Principal Stress on the Deformation of Saturated Clay

Abstract

One-way cyclic loading induced by traffic loads will give rise to the cyclic variation of normal stress components of all three directions, including one vertical and two horizontal ones. The cyclic horizontal normal stress perpendicular to the driving direction is considered to be negligible compared to the other one parallel to the driving direction. Recognizing this, the coupling of cyclic vertical normal stress and cyclic horizontal normal stress parallel to the driving direction is simulated by the combination of cyclic major and intermediate principal stresses based on an advanced true triaxial apparatus. A parameter of coefficient of cyclic intermediate principal stress, bcyc, is introduced to characterize the coupling effects. A series of one-way cyclic true triaxial tests was performed on a remolded saturated clay, and the emphases were placed on the permanent major and intermediate principal strains. Test results show that the cyclic intermediate principal stress has great influence on the deformation characteristics, and the influences on the permanent major and intermediate principal strains are very different. The permanent major principal strains were found to decrease linearly with the increase of bcyc, and a critical value of bcyc≈.48 appeared to exist, at which the permanent intermediate principal strains changed the direction from tension to compression.