One-Dimensional Compression Behavior of Calcareous Sand and Marine Clay Mixtures

More and more oceanic projects involve calcareous sand-marine clay mixtures which behave totally different from pure calcareous sand and marine clay. The effect of clay content on the compression behavior of the calcareous sand-marine clay mixture is investigated in this study. The results reveal that the coefficient of volumetric compressibilitym(v)will be affected significantly by the clay content at low stress state (i.e., vertical stress less than 600 kPa), but the influence of the clay content onm(v)can be neglected at high stress states. Further laboratory tests found that the effect of clay content on the creep behavior is negligible for a marine clay fraction of 30% or less, but the effect increases with clay contents larger than 30%. In addition, the particle breakage characteristics are investigated from particle size distributions before and after application of loading in oedometer tests. A general correlation is obtained from the test data to evaluate particle breakage ratioB(r)by clay contentrand magnitude of loadp. Finally, a modified conceptual model based on Lade's transitional fine content (TFC) model is proposed to predict the transitional state of the mixture by considering volume change induced by the sand breakage. The model is used to analyze the critical clay content at transitional state based on some reasonable assumptions and a very good prediction can be obtained.