Loess exhibits typical water sensitivity and dynamic vulnerability. The combination of rainfall and earthquake-related issues presents a complex disaster process, posing a significant threat to the infrastructure in the loess region. A cyclic simple shear test was conducted on undisturbed loess under a constant vertical stress ranging from 50 to 300 kPa, comprising three stages(C-W-D): consolidation, pre-humidification, and cyclic loading. The deformation behavior under humidification and cyclic loading was analyzed. The microstructure evolution of loess during three stages was examined using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). Results indicated that: (1) Cyclic deformation increased with the rise in vertical stress , humidification parameters , and dynamic shear stress amplitude . The sensitivity of cyclic deformation to and gradually decreased as increases. (2) The total deformation in the three stages correlated positively with , , and . The proportion of humidification deformation and cyclic deformation in the total deformation was largely unaffected by , with cyclic deformation gradually dominating as increases. (3) The pre-humidification stage promoted aggregates and the formation of numerous intergranular pores. Cyclic loading mainly leads to the change of pore structures, forming obvious seismic damage area. Based on the relationship between humidification deformation and cyclic deformation, a loess deformation prediction model was proposed, which can comprehensively consider , , and . This can provide a theoretical reference for earthquake disaster prediction in collapsible loess areas.

中文翻译：

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预加湿过程下原状黄土循环加载变形响应及微观结构演化


黄土具有典型的水敏感性和动力脆弱性。降雨和地震相关问题的结合呈现出复杂的灾害过程，对黄土地区的基础设施构成重大威胁。在 50 至 300 kPa 的恒定垂直应力下对原状黄土进行循环简单剪切试验，包括三个阶段（C-W-D）：固结、预增湿和循环加载。分析了加湿和循环加载下的变形行为。使用扫描电子显微镜（SEM）和压汞孔隙率测定法（MIP）研究了黄土在三个阶段的微观结构演变。结果表明：（1）循环变形随着竖向应力、加湿参数和动剪应力幅值的增大而增大。循环变形对 和 的敏感性随着增大而逐渐降低。 (2) 三个阶段的总变形量与 、 、 、 呈正相关。加湿变形和循环变形占总变形的比例基本不受 影响，随着增大，循环变形逐渐占主导地位。 (3)预增湿阶段促进团聚和大量粒间孔的形成。循环荷载主要导致孔隙结构发生变化，形成明显的震害区。基于加湿变形与循环变形的关系，提出了综合考虑 、 、 和 的黄土变形预测模型。这可为湿陷性黄土地区地震灾害预测提供理论参考。