底泥固结对污染物运移影响的超重力离心试验模拟

发布时间：2018-05-08 10:20

本文选题：离心机试验 + 底泥覆盖　；参考：《浙江大学学报(工学版)》2016年01期

【摘要】：为了研究污染底泥覆盖技术中添加覆盖层造成底泥固结排水、以对流方式加速污染物击穿覆盖层的过程,利用超重力离心模型试验的缩尺缩时效应,研究添加覆盖层后底泥固结对污染物运移速度及出流量的影响,采用数值方法对试验进行模拟.结果表明:1)添加覆盖层后上覆水体中氯离子质量浓度随时间的变化过程,与底泥固结沉降量随时间的变化过程具有较好的相关性.底泥固结排出的孔隙水以对流方式显著加快污染物向上覆水体运移,仅考虑污染物以扩散方式运移的底泥覆盖设计方法偏不安全.2)覆盖层对底泥污染物运移有一定的延滞作用,1cm厚度覆盖层的上覆水层中氯离子质量浓度比3cm厚度情况高85.7%,增加覆盖层厚度可以显著地减少底泥污染物运移到上覆水体的量.3)采用分层总和法计算得到的底泥沉降与实测值接近,平均相差为8.7%;试验底泥固结时间介于以2种排水路径(添加覆盖层固结前、后底泥高度)计算得到的时间之间,通过超重力离心模型试验模拟底泥固结过程是可行的.4)覆盖层引起的底泥沉降的数值计算值较实测值偏大(平均相差10.9%),上覆水体污染物质量浓度的数值计算值较实测值偏小(平均相差16.6%).5)数值分析表明,与纯扩散相比,底泥固结造成污染物击穿覆盖层时间缩短40.7倍.
[Abstract]:In order to study the consolidation and drainage of sediment by adding overburden in the technology of contaminated sediment cover and to accelerate the process of pollutant breaking through the overburden by convection, the scaling time effect of hypergravity centrifugal model test was used. The effect of sediment consolidation on pollutant migration velocity and discharge rate after adding overburden was studied and the experiment was simulated by numerical method. The results show that the mass concentration of chloride in the overlying water after the addition of overburden has a good correlation with the time process of the consolidation settlement of the sediment and the change process of the concentration of chloride ion in the overlying water with the addition of the overburden. The pore water discharged by the consolidation of the sediment significantly accelerates the transport of pollutants to the overlying water body in a convective manner. The design method of sediment cover with only considering the diffusion of pollutants is not safe. 2) the overlying water layer with the thickness of 1 cm has a certain delay effect on the transport of pollutants in the sediment. The mass concentration of chlorine ion in the overlying water layer with the thickness of 1 cm is higher than that of the 3cm thickness of the overlying water layer. Increasing the thickness of the overburden can significantly reduce the amount of sediment contaminants transported to the overlying water body. 3) the sediment settlement calculated by the method of stratified summation is close to the measured value. The average difference is 8.7. The consolidation time of the test sediment is between the time calculated by two drainage paths (the height of the sediment before and after the consolidation of the overburden), It is feasible to simulate the consolidation process of sediment by hypergravity centrifugation model test. 4) the calculated value of sediment settlement caused by overburden is larger than the measured value (average difference is 10.9%, and the value of mass concentration of pollutants in overlying water is higher than that of measured value). Numerical analysis shows that the measured values are small (the average difference is 16.6g / 5). Compared with pure diffusion, the time of pollutant breakdown is reduced by 40.7 times.
【作者单位】：浙江大学软弱土与环境土工教育部重点实验室;浙江大学岩土工程研究所;
【基金】：国家自然科学基金青年科学基金资助项目(51009121)
【分类号】：X52

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