段钊,董晨曦,郑文杰,等.2020.滑坡冲击作用下的阶地砂质粉土层液化机理[J].工程地质学报,28(6):1362-1371.doi: 10.13544/j.cnki.jeg.2019-491.
    引用本文: 段钊,董晨曦,郑文杰,等.2020.滑坡冲击作用下的阶地砂质粉土层液化机理[J].工程地质学报,28(6):1362-1371.doi: 10.13544/j.cnki.jeg.2019-491.
    Duan Zhao,Dong Chenxi,Zheng Wenjie,et al.2020.Liquefaction mechanism of sandy silt of terrace under landslide impact[J].Journal of Engineering Geology,28(6):1362-1371.doi: 10.13544/j.cnki.jeg.2019-491.
    Citation: Duan Zhao,Dong Chenxi,Zheng Wenjie,et al.2020.Liquefaction mechanism of sandy silt of terrace under landslide impact[J].Journal of Engineering Geology,28(6):1362-1371.doi: 10.13544/j.cnki.jeg.2019-491.

    滑坡冲击作用下的阶地砂质粉土层液化机理

    LIQUEFACTION MECHANISM OF SANDY SILT OF TERRACE UNDER LANDSLIDE IMPACT

    • 摘要: 为探究阶地饱和砂质粉土在黄土滑坡冲击荷载作用下的力学机理,选取泾阳南塬典型黄土滑坡LD37为研究对象。通过基本性质测试获取了阶地砂质粉土的物理、水理、颗粒级配和矿物组分等指标。采用自制冲击设备进行了3种饱和度条件下的冲击试验,并对水分迁移和剪切强度变化等问题进行了分析,在此基础上探讨了冲击液化机理。结果表明:冲击荷载会使砂质粉土内部的总应力与孔隙水压力剧增,在应力波的作用下,出现多个峰值,且孔隙水压力在1 s内难以完全消散;80%与90%饱和度的砂质粉土受冲击会在深度方向上形成不同程度的液化,而70%饱和度的砂质粉土受冲击后沿深度方向并未发生液化;砂质粉土发生冲击液化时下部水分会向上部迁移,导致其上部土层含水率骤增,剪切强度骤减;冲击液化过程可划分为初始阶段、冲击挤压阶段和冲击回弹阶段。砂质粉土的冲击液化机理是一种由于快速冲压土体的不排水行为,导致其颗粒原始骨架结构破坏重组,从而引起其内部孔压快速积累的一种液化行为。

       

      Abstract: Recently, some scholars have noticed the liquefaction phenomenon of unsaturated sandy silt caused by the impact in the study of loess landslide in south Jingyang platform. This kind of liquefaction phenomenon is special because it is induced by a single impact load rather than a continuous cyclic load. The impact load has the characteristics of high strength, short time, and strong stress wave propagation effect. In order to study the mechanism of this impact liquefaction phenomenon, the paper built a landslide geological generalized model based on the geological background of loess landslide in south Jingyang platform and analyzed the variation of pore water pressure and total stress of sandy silt with different saturations in the same impact condition. The water content and shear strength of sandy silt after impact were also measured. The result shows that:(1)During impact load, the total stress and the pore water pressure in sandy silty are suddenly increased, and several pressure peaks occur because of the transfer of stress waves. While the wave disappears, the excess pore water pressure turns into the residual pore water pressure which remains stable for a period of time; (2)Under the impact of 80% and 90% saturation, sandy silty soil has different degrees of liquefaction at different layers, while sandy silty soil under the same condition of 70% saturation is not liquefied after impact; (3)The water in the lower part migrates to the upper part during and after the impact process. As a result, the water content of the surface soil increased, and the shear strength decreased; (4)The impact liquefaction mechanism of sandy silty is a rapidly destroying and recombining behavior of the original skeleton structure in an undrained condition, which causes the rapid accumulation of pore water pressure.

       

    /

    返回文章
    返回