氯离子在黏土-膨润土屏障中迁移的离心试验研究

将对流-扩散试验装置置于土工离心机中，以50g离心加速度运行12 h，研究了黏土-膨润土混合土样中Cl-的迁移扩散，使用解析解对试验结果进行拟合确定相关参数，分析了试验的相似条件，使用商用软件对离心试验原型进行模拟，与试验结果进行比较，探讨了离心机用于溶质迁移分析的比尺效应，最后通过数值分析研究了试验的黏土-膨润土屏障用于老垃圾填埋场防渗帷幕补强的效果。结果表明，土工离心机试验中，按实际出流量计算的实际孔隙水流速小于临界流速，两试样中的佩克莱数（Pe数）小于临界Pe数，机械弥散的作用可以忽略，试验满足扩散的相似定律；离心机试验所模拟的2.5 m厚衬垫原型，在水头5 m和10 m作用下3.42 a后均未被击穿；常重力下试验土样的渗透系数为8.5×10-8 cm/s，有效扩散系数为7.82×10-7 cm2/s，对试验原型进行的数值模拟表明，n倍重力加速度下，土工离心机可以 尺寸的试样实现对原型的模拟，同时将对流和扩散作用下的溶质迁移时间缩短至原型的 ；试验的黏土-膨润土屏障用于老垃圾填埋场防渗补强，可显著减缓溶质迁移，防渗补强后可满足渗滤液迁移扩散的控制要求。

Centrifuge study of migration of Cl- in clay-bentonite barriers

Advection-diffusion apparatus was installed on a geotechnical centrifuge under 50g to run for 12 hours in order to investigate migration of Cl- in clay-bentonite barriers. Analytic solution was used to calculate the diffusion parameters. The scaling requirement was studied. The prototype of the centrifuge test was simulated by commercial software and the scale law of solute migration in geotechnical centrifuge was discussed. Efficiency of the tested clay-bentonite barriers used as an amendment measure in an old landfill to prevent pollution was analyzed by numerical simulation. In the centrifuge test, the actual advection velocity and the Péclet number calculated from outflow are smaller than the critical values. Mechanical dispersion can be neglected and the consistent scaling law can be satisfied. Breakthrough has not happened after 3.42 years for the simulated layer with a prototype thickness of 2.5 m and the hydraulic heads of 5 m and 10 m. Saturated hydraulic conductivity and effective dispersion coefficient of the tested soil are 8.5×10-8 cm/s and 7.82×10-7 cm2/s, respectively. Numerical simulation of the centrifuge test prototype shows that under a centrifugal acceleration of ng, solute migration under advection and dispersion in the prototype can be modeled in the centrifuge in size and time. If the tested clay-bentonite is used in old landfills for amendment of early barriers, the migration can be significantly slowed down and the requirement of pollution control can be satisfied.