<p>Static fatigue refers to the failure of materials under sustained stress levels lower than their short-term strength, which significantly affects the long-term stability of structures built on or within calcareous sand. This study investigates the progressive static fatigue behavior of calcareous sand, a material widely encountered in geotechnical engineering. Despite its widespread distribution, the underlying mechanisms governing the time-dependent mechanical degradation of calcareous sand remain insufficiently explored, necessitating further research. In this work, we employed an advanced non-destructive monitoring method, acoustic emission (AE) technology, to track real-time internal microstructural evolution, enabling a more detailed investigation of progressive failure mechanisms at a microscopic scale. Specifically, AE parameters such as hit rate and frequency characteristics are analyzed to provide quantitative insights into the initiation and propagation of micro-cracks. By utilizing AE monitoring, this research systematically evaluates the time-dependent mechanical degradation of calcareous sand under sustained loading, identifying key AE signatures associated with different phases of the static fatigue process. The findings offer valuable insights into the micro-mechanical behavior of calcareous sand during sustained loading, contributing to a better understanding of its long-term deformation and failure characteristics in engineering applications.</p>