滑坡剪切带土循环加卸载三轴试验及细微观结构研究

    Research on cyclic loading-unloading triaxial test and fine microstructure of Guoyemoli landslide shear zone soil in Zhouqu

    • 摘要: 为揭示含水率与围压对滑坡剪切带土循环力学特性的影响,开展了不同含水率与围压下的三轴循环加卸载试验,并结合扫描电镜(SEM)对其微结构进行分析。试验表明:3次加卸载曲线均呈现明显滞回圈,回弹模量受压实度和含水率影响显著。在相同压实度与围压下,含水率越高回弹模量越大;在相同含水率与围压(50 kPa)下,压实度越高回弹模量越大。当试样接近饱和或围压增至100 kPa时,回弹现象明显减弱。SEM观测显示土体黏土矿物定向排列,微孔隙与裂隙发育,导致孔隙率增高,在剪切破坏与地下水作用下易形成高孔隙水压力,诱发滑坡。微结构特征可反演滑坡活动历史与形成机理,为滑坡防治与稳定性评价提供依据。

       

      Abstract: To reveal the effects of moisture content and confining pressure on the cyclic mechanical properties of soils in landslide shear zones, triaxial cyclic loading-unloading tests are conducted under different moisture contents and confining pressures, combined with scanning electron microscopy (SEM) for microstructural analysis. The experimental results show that three loading-unloading curves exhibit distinct hysteresis loops, and the resilient modulus is significantly affected by compaction degree and moisture content. Under the same compaction degree and confining pressure, the higher the moisture content, the larger the resilient modulus. Under the same moisture content and confining pressure (50 kPa), the higher the compaction degree, the larger the resilient modulus. When the samples approached saturation or the confining pressure increases to 100 kPa, the resilience phenomenon weakens significantly. SEM observations show that the clay minerals in the soil are arranged in an oriented manner, with the development of micropores and fissures, which led to an increase in porosity. Under the combined action of shear failure and groundwater, high pore water pressure is easily generated, thus inducing landslides. The microstructural characteristics can be used to invert the activity history and formation mechanism of landslides, providing a basis for landslide prevention and control as well as stability evaluation.

       

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