Abstract Calcareous sand has been used as the main filling material in numerous reef constructions. Therefore, understanding its long-term dynamic engineering geological characteristics under cyclic applications of traffic or wave loading is crucial to the design and prediction of the serviceability of reef infrastructures. Considering this, seven monotonic triaxial tests and 33 high-cycle (25,000 cycles) drained triaxial tests were conducted on calcareous sand with various mean effective stresses (p’) and cyclic stress ratios (ζ). The results show that the development of the accumulated axial strain (e1acc) has a strong correlation with the positional relationship between the cyclic stress path and critical strength line (CSL) or static strength envelope (SSE) in the p’-q plane. The critical cyclic stress ratio ζc, that represents the cyclic stress path reaching the CSL, is proposed. When ζ>ζc, the growth rate of e1acc with ζ increases drastically. Moreover, when the cyclic stress path approaches the SSE, e1acc enters an incremental collapse state. The increase in p’ diminishes the dilatancy of the volumetric strain ev. However, this response of ev reverses from decreasing to increasing with increasing ζ. The resilient modulus (Mr) increases with the number of cycles (N) due to the initial densification. If ev dilation occurs, Mr will decrease with N as particles lose contact. A single parameter for the cyclic stress path ratio (ψ) considering the effects of p’, ζ, and SSE is proposed. Additionally, empirical formulas for calculating the ultimate e1acc and Mr are established. Furthermore, particle degradation significantly worsens e1acc and ev, but has a more profound effect on the compressibility of ev. This degradation is also detrimental to Mr. A certain deviation trend of the predicted values from the measured values is found to correspond with the relative particle breakage.

中文翻译：

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循环荷载作用下钙质砂的长期行为与降解

摘要 钙质砂已成为众多礁石建筑的主要填充材料。因此，了解其在交通或波浪载荷循环应用下的长期动态工程地质特征，对于珊瑚礁基础设施的可服务性设计和预测至关重要。考虑到这一点，在不同平均有效应力 (p') 和循环应力比 (ζ) 的钙质砂上进行了 7 次单调三轴试验和 33 次高循环（25,000 次循环）排水三轴试验。结果表明，累积轴向应变 (e1acc) 的发展与循环应力路径与临界强度线 (CSL) 或 p'-q 平面中的静强度包络线 (SSE) 之间的位置关系具有很强的相关性。临界循环应力比 ζc，提出了代表到达 CSL 的循环应力路径。当 ζ>ζc 时，e1acc 与 ζ 的增长率急剧增加。此外，当循环应力路径接近 SSE 时，e1acc 进入增量坍塌状态。p' 的增加减小了体积应变 ev 的剪胀性。然而，随着 ζ 的增加，ev 的这种响应从减少到增加。由于初始致密化，弹性模量 (Mr) 随着循环次数 (N) 的增加而增加。如果发生 ev 膨胀，随着粒子失去接触，Mr 将随 N 减小。考虑到 p'、ζ 和 SSE 的影响，提出了循环应力路径比 (ψ) 的单个参数。此外，还建立了计算最终e1acc和Mr的经验公式。此外，粒子降解显着恶化 e1acc 和 ev，但对 ev 的可压缩性有更深远的影响。这种退化也对 Mr. 不利。预测值与测量值的某种偏差趋势被发现与相对的颗粒破损相对应。