Effects of intermittent cyclic loading with cyclic confining pressure on deformation behaviors of saturated clay

Traffic loading is composed of cyclic loading and intermittent periods, in which the influences of intermittent period on the dynamic characteristics of soil cannot be ignored. The stress field in subgrade soil caused by the traffic loading includes cyclic deviator stress and cyclic confining pressure. Therefore, a series of cyclic triaxial tests in intermittent cyclic loading mode with cyclic confining pressure are carried out to study the deformation behaviors of saturated clay, and the effects of the cyclic confining pressure and drained conditions during the intermittent period are investigated. The results show that the relationship between the accumulated axial strain increment and the loading stages are similar under different test conditions: the accumulated axial strain increment gradually decreases as the loading stage increases. Additionally, the variation of the accumulated axial strain increment is also affected by the cyclic confining pressure, in which the accumulated axial strain increment decreases with the increasing cyclic confining pressure. Besides that, the variations of accumulated axial strain are also different under different drained conditions during the intermittent period: the excess pore water pressure induced in cyclic loading period dissipates under partially drained conditions during the intermittent period, leading to that the accumulated axial strain of soft clay increases in a certain extent during the intermittent period; part of the deformation produced during the cyclic loading period can recover under undrained conditions during the intermittent period, and the accumulated axial strain of soft clay decreases. The above test results may deepen the understanding of the deformation behaviors of soft clay under intermittent cyclic loading.