Flow sliding instability of saturated loess slopes is a common geological hazard in loess areas of China. Previous studies have found that the occurrence of flow-slip loess landslides is closely related to static liquefaction and is controlled by physical characteristics and load conditions. In this work, we comprehensively study these influences of physical properties (i.e. initial pore structure, gradation, dry density) and shear rate on the static liquefaction of saturated loess through a series of consolidated undrained triaxial tests, and the effect mechanism of these related factors on the static liquefaction of saturated loess are also discussed. The results present that: (1) The peak deviator stress and the maximum pore pressure of the undisturbed loess are much greater than these of the remodeled one under each level of confining pressure (except 450 kPa). Further, the calculated liquefaction potential index (LPI) of undisturbed loess is much greater, indicating that undisturbed loess is more prone to static liquefaction due to the initial pore structure. (2) The lower the relative clay/silt content ratio of the saturated remodeled loess, the stronger the potential liquefaction ability. With the increase of the relative content of clay from 0.125 to 0.698, the stress-strain curve gradually transitions from strain softening to hardening. (3) The remodeled loess show the steady-state strength tends to continuously increase with the increase of dry density from 1.38 g/cm to 1.56 g/cm, while the LPI increases first and then decreases, and the largest value appears when the dry density reaches to 1.44 g/cm. The reason is that the value of 1.44 g/cm is the normal consolidated condition, which essentially reflects the potential liquefaction change during the transformation from under consolidated to over consolidated state.(4) The effect of shear rate on the stress-strain curve of remolded loess is not significant, but the peak strength and ultimate pore pressure show a trend of increasing and then decreasing with the increase of shear rate. There exists a “critical shear rate “of 0.1 mm/min reflecting the liquefaction of loess is more likely to occur when reaches to this critical value. (5) Based on the comparison of static liquefaction tests, the influencing factors of static liquefaction of saturated loess are: initial pore structure> gradation > dry density > shear rate. This study can provide a systematic evaluation for understanding the influencing factors of static liquefaction capacity of saturated loess (especially remolded one), and also has a reference for explaining the loess flow-sliding failure mechanism under disturbance conditions.

中文翻译：

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物理性质和剪切速率对饱和黄土静态液化的影响


饱和黄土边坡流滑失稳是我国黄土地区常见的地质灾害。前期研究发现，流滑型黄土滑坡的发生与静态液化密切相关，并受物理特性和荷载条件控制。本工作通过一系列固结不排水三轴试验，综合研究了物理性质（初始孔隙结构、级配、干密度）和剪切速率对饱和黄土静态液化的影响，以及这些相关因素的影响机制。并对饱和黄土的静态液化问题进行了讨论。结果表明：（1）在各级别围压（450 kPa除外）下，原状黄土的峰值偏应力和最大孔隙压力均远大于改造后的黄土。此外，计算出的原状黄土的液化潜力指数（LPI）要大得多，表明原状黄土由于初始孔隙结构更容易发生静态液化。 (2)饱和重塑黄土的粘土/粉粒相对含量比越低，潜在液化能力越强。随着粘土相对含量从0.125增加到0.698，应力应变曲线逐渐由应变软化向硬化转变。 (3) 重塑黄土的稳态强度随着干密度从1.38 g/cm3增加到1.56 g/cm3而呈现持续增加的趋势，而LPI则先增大后减小，且在干密度时出现最大值。密度达到1.44g/cm3。原因是值为1。44 g/cm为正常固结状态,本质上反映了由欠固结状态向过固结状态转变过程中潜在的液化变化。(4)剪切速率对重塑黄土应力应变曲线的影响不显着,但随着剪切速率的增大，峰值强度和极限孔隙压力均呈现先增大后减小的趋势。存在0.1毫米/分钟的“临界剪切速率”，反映达到该临界值时黄土更容易发生液化。 (5)通过静态液化试验对比，饱和黄土静态液化的影响因素为：初始孔隙结构>级配>干密度>剪切速率。该研究可为了解饱和黄土（尤其是重塑黄土）静态液化能力的影响因素提供系统评价，也为解释扰动条件下黄土流滑破坏机理提供参考。