The Effect of Different Clay Contents on the Creep Characteristics of Calcareous Sand

Abstract The geotechnical characteristics of calcareous sand are intrinsically linked to the development and execution of island and reef construction projects. During the reclamation process for islands and reefs, the inevitable inclusion of fine particles can lead to the formation of mixed soil bodies, thereby affecting the overall stability of the island or reef. To investigate the effect of different clay contents on creep characteristics of calcareous sand, triaxial stepped loading creep tests were systematically conducted on calcareous sand with varying clay content percentages, specifically at 0%, 2%, 10%, and 20% in the study. It is found that with increasing clay content, the amount of creep deformation initially decreases and then increases. There exists an optimal clay content between 2% and 10% that enhances the overall strength of the calcareous sand. Additionally, when the creep deviatoric stress is low, the creep of calcareous sand exhibits nonlinear decelerative creep. When the creep deviatoric stress is relatively high, the creep rate initially decreases and then increases, leading to overall creep failure. As the clay content increases, the role of fine particles in calcareous sand transitions from filling voids and enhancing the interparticle interlocking to predominantly providing lubrication and weakening the particle interlocking. During creep, there is a transient but significant creep structure effect that causes a marked reduction in the creep rate when the sample transitions to the next stage. This effect persists until the creep structure is disrupted, leading to an augmentation in the creep rate and a subsequent reversion to the initial creep pattern.