成层砂土中细颗粒迁移沉积特性试验研究

    EXPERIMENTAL STUDY ON THE DEPOSITION CHARACTERISTICS OF FINE PARTICLE MIGRATION IN STRATIFIED SANDY SOILS

    • 摘要: 成层土广泛存在于第四纪沉积层,研究成层砂土中细颗粒迁移沉积特性对地下水回灌、注浆等工程具有重要意义。采用室内一维砂柱试验系统,选取3种粒径范围的砂土和21种典型分层方式对悬浮颗粒在饱和砂层中的迁移沉积过程进行研究。结果表明:不同的层状排序对悬浮颗粒的穿透曲线、沉积量和中值粒径有较大影响。当小粒径多孔介质覆盖大粒径多孔介质时,悬浮颗粒的穿透曲线会产生二次峰值,颗粒沉积量随着迁移距离的增加而减少,其沉积颗粒的中值粒径反而增大;当大粒径多孔介质覆盖小粒径多孔介质时,悬浮颗粒的穿透曲线只有一次峰值,颗粒的沉积量在分层处发生突增现象,沉积颗粒的中值粒径在砂柱中部减小。根据渗透系数的变化情况,将悬浮颗粒运动状态分为:沉淀、剥离运移。

       

      Abstract: Quaternary sedimentary strata frequently contain formation soils,therefore understanding the features of how tiny particles in these soils migrate and deposit is crucial for groundwater recharge and grouting projects. Using an indoor,one-dimensional sand column test setup with three different grain size ranges of sandy soils and 21 common stratification techniques,the migration deposition process of suspended particles in saturated sand layers was examined. The findings demonstrate that the penetration curve,particle deposition rate,and median particle size of suspended particles are significantly affected by different stratification sequencing. The penetration curve of suspended particles creates a secondary peak when small-size porous media covers large-size porous media. The number of particles deposition reduces as migration distance rises,but the median particle size of deposited particles increases instead; When large-sized porous media cover smaller-sized porous media,the penetration curve of suspended particles has only one peak,the amount of particles deposited increases suddenly at the stratification,and the median particle size of deposited particles decreases in the middle of the sand column. According to the variation of permeability coefficient,the suspended particles movement state is classified as: sedimentation,stripping transport.

       

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