中文摘要：

钙质砂是海洋沉积物中的一种，富含碳酸钙或其他难溶碳酸盐类物质的特殊介质。由于其颗粒质脆，受力后易产生破碎，表现出与常规陆源砂不同的力学性质。通过对取自南沙群岛永暑礁附近海域的钙质砂进行三轴剪切试验，分析了钙质砂颗粒破碎与剪胀对其抗剪强度的影响。试验结果表明，颗粒破碎与剪胀对钙质砂强度有着重要影响，低围压下剪胀对其强度的影响远大于颗粒破碎，随着围压的增加，钙质砂颗粒破碎加剧，剪胀影响越来越小，而颗粒破碎的影响则越来越显著；颗粒破碎对强度的影响随着围压的增大而增大，当破碎达到一定程度后颗粒破碎渐趋减弱，其影响也渐趋于稳定。

英文摘要：

Calcareous sediments generally consist of the remains of marine organism, which tend to crush relatively easily under load, compared to terrigenous materials. Based on the data of triaxial shear tests carried out on calcareous sand taken from the South China Sea, the influences of the particle breakage and dilatancy on shear strength of calcareous sands are discussed and analyzed. The results indicate that the particle breakage and dilantacy have significant effect on the shear strength of calcareous sands. The effect of the dilatancy on the shear strength is more serious than that of the particle breakage under low confining pressure, while with the confining pressure increasing, the effect of the particle breakage increase and that of dilatancy decrease. When the confining pressure attained to some extent, the particle breakage and its effect on shear strength will diminish.