新疆粉土类斜坡水劣化变形破坏试验及模拟研究

含水率对于粉土强度特性影响较大。尤其是对于粉土类土质边坡,天然状态下稳定性较好,但遇到暴雨或者持续性降雨等情况下,容易触发不稳定斜坡发生滑动。以乌鲁木齐某地铁沿线土质斜坡为例,现场取样后通过人工改变粉土含水率进行三轴压缩试验,综合分析围压及含水率对抗剪强度耦合影响,并将不同含水率下的强度参数运用至三维颗粒流程序(PFC)建立的边坡模型,研究边坡的变形破坏特征。结果显示:内摩擦角随着含水率的增加而不断减小,黏聚力则随着含水率的增加呈现出先增大后减小的变化特征,且下降幅度远大于上升量。抗剪强度与黏聚力具有相近的变化规律。土体强度衰减后,斜坡的变形破坏机理表现为后缘拉裂-坡体中部牵引-前缘剪出的特征。以滑带节理裂隙和滑体位移的分布为评价指标,从微观角度研究随着粉土含水率的增加,坡体变形破坏发展全过程。为该类滑坡在降雨作用下的稳定性评价及防治提供理论支撑。

Experimental and numerical study on failure and deformation of silty slope influenced by water degradation in Xinjiang

Water content has great influence on the strength characteristics of silt. Especially for the silty soil slope, the stability is good in the natural state, but it is more easier to trigger the slide of unstable slope under heavy rain or continuous rain condition. Take one unstable soil slope along a highway in urumqi as an example,The triaxial compression test was carried out with sample taken from slope, the moisture content of which is changed manually. The strength parameters under different moisture content were applied to the slope model established by the three-dimensional particle flow program (PFC) to study the deformation and failure characteristics of the slope. The results show that the Angle of internal friction decreases with the increase of moisture content. With the increase of moisture content, the cohesive force increases first and then decreases. The variation law of shear strength and cohesive force is similar. After soil strength attenuation, the deformation and failure mechanism of the slope is shown as the characteristics of trailing edge tensile crack - traction in the middle of slope body - front shear. Taking the distribution of slope displacement and joint fracture as evaluation indexes, the whole process of slope deformation and failure development was studied from the micro perspective with the increase of silt moisture content. It may provide theoretical support for the stability evaluation and prevention of this kind of landslide.