Abstract In practical engineering, liquefiable sand deposits in natural or manmade slopes, dams, and embankments may contain a certain amount of silty fines and often sustain a static shear prior to subsequent cyclic loading. To understand the effect of static shear stress on the cyclic liquefaction behavior of silty sand, a small amount of crushed fines was added to clean sand, and a series of triaxial tests considering a wide range of static and cyclic shear stress levels were performed. The results indicate that different stress conditions result in two liquefaction failure patterns for silty sand: cyclic mobility and residual deformation accumulation. A comparison of the liquefaction responses of silty and clean sands with the same relative density confirms that the former typically has a moderately higher cyclic resistance than the latter, which can be explained by the reinforced effect of fines on the soil skeleton. It is also demonstrated that the flow deformation type behavior accompanied by rapid development of pore pressure and severely degraded stiffness is more prominent in clean sand, which is responsible for the continuous decrease in its liquefaction resistance when the extensional static stress increases. Furthermore, a unique correlation of equivalent modulus versus cyclic strain amplitude is observed, which depends significantly on the static shear stress level but relatively insensitive to the addition of fines at least up to the considered fines content.

中文翻译：

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考虑静态剪切效应的洁净砂和粉砂的循环液化行为比较

摘要 在实际工程中，天然或人造边坡、大坝和堤防中的可液化砂沉积物可能含有一定量的粉质细粒，并且在随后的循环加载之前通常会承受静态剪切。为了解静态剪应力对粉质砂循环液化行为的影响，将少量粉碎的细粉添加到清洁砂中，并进行了一系列考虑各种静态和循环剪应力水平的三轴试验。结果表明，不同的应力条件导致粉砂的两种液化破坏模式：循环流动和残余变形积累。对具有相同相对密度的粉质砂和清洁砂的液化响应进行比较，证实前者通常比后者具有适度更高的循环阻力，这可以通过细粒对土壤骨架的增强作用来解释。还表明，伴随着孔隙压力的快速发展和刚度严重退化的流动变形型行为在清洁砂中更为突出，这是当拉伸静应力增加时其液化阻力不断降低的原因。此外，观察到等效模量与循环应变幅度的独特相关性，这显着取决于静态剪切应力水平，但对添加细粉相对不敏感，至少达到所考虑的细粉含量。还表明，伴随着孔隙压力的快速发展和刚度严重退化的流动变形型行为在清洁砂中更为突出，这是当拉伸静应力增加时其液化阻力不断降低的原因。此外，观察到等效模量与循环应变幅度的独特相关性，这显着取决于静态剪切应力水平，但对添加细粉相对不敏感，至少达到所考虑的细粉含量。还表明，伴随着孔隙压力的快速发展和刚度严重退化的流动变形型行为在清洁砂中更为突出，这是当拉伸静应力增加时其液化阻力不断降低的原因。此外，观察到等效模量与循环应变幅度的独特相关性，这显着取决于静态剪切应力水平，但对添加细粉相对不敏感，至少达到所考虑的细粉含量。