Thermomechanical volume change behavior of deep-water sediment

Understanding the thermomechanical behavior of deep-water sediment is essential for the safety design of deep-water engineering structures. In this study, a series of temperature-controlled oedometer tests was conducted to explore the volume change behavior of the deep-water sediment sampled from the South China Sea. The experimental results showed that for the normally consolidated specimens, the thermal volume change was independent of the effective vertical stress and decreased with the increasing number of thermal cycles. The thermal volume change was closely related to the recent stress history. The contractive volumetric strain decreases and the expansive one increases with increasing OCRs under heating conditions. Under the reloading conditions, the overconsolidated specimens during heating show contractive behavior and the magnitude of the contractive volumetric strain depends on the reloading path. The thermal volumetric strain induced by secondary consolidation plays a main role on the deformation of the normally consolidated or reloaded specimens under heating conditions. A reloading index is proposed to characterize quantitatively the thermal volumetric strain of the overconsolidated specimens under heating conditions simply and effectively when the reloading stress is lower than the yield stress.