磷矿粉改性土-膨润土隔离墙增强重金属阻隔性能机理研究

土-膨润土隔离墙是治理水土重金属污染的常用阻隔技术，但其在化学场中阻隔性能存在劣化和失效风险。为此，本研究拟采用磷矿粉作为改性材料，以改善化学场中隔离墙阻隔性能。研究工作包括：（1）联合batch试验与微观分析，研究磷矿粉改性土-膨润土混合材料的吸附行为，揭示其微观机理，提出考虑相关因素影响的吸附模型；（2）开展单参数确定的土柱试验与微观分析，系统研究化学场对磷矿粉改性隔离墙渗透、吸附特性的影响机理，评估其在化学场中的相容性；（3）对比batch试验与土柱试验结果，揭示batch试验与土柱试验中吸附行为差异的微观机理，提出基于batch试验吸附模型确定土柱状态吸附模型的方法；（4）采用离心模型试验，模拟磷矿粉改性隔离墙中重金属迁移行为，建立竖向扩散、水平对流-弥散的二维迁移模型，预测磷矿粉改性隔离墙的击穿时间。研究成果为提出一种经济、有效的隔离墙阻隔性能磷矿粉改良技术提供理论基础。

Soil-bentonite cutoff wall (SB) is a kind of commonly used blocking technology to control the underground heavy metal pollution, which may has performance degradation and failure risk in chemical field. Phosphate rock (PR) power is added to improve SB’s performance. The following work is planned in this proposal: (1) adsorption behavior and mechanism of PR powder modified soil-bentonite mixture are studied by combination of batch test methods and microscopic analysis, and the microscopic mechanism is revealed; (2) the soil column test groups for single parameter determination and microscopic analysis are carried out to study the influence of chemical field system on characteristics and mechanism of permeability and adsorption of modified cutoff wall, its chemical compatibility is evaluated; (3) based on the results of batch test and soil column test, microcosmic mechanism of difference in adsorption behavior of batch test and soil column experiment is revealed, and the method of determining the adsorption model of soil column was proposed based on adsorption model from the batch test; (4) centrifuge modelling test is carried out to investigate the heavy metal migration behavior in PR-amended cutoff wall, and a two-dimensional migration model of vertical diffusion and horizontal advection-dispersion is established, the breakthrough time of PR powder modified cutoff wall is predicted. Research results provide a theoretical basis for putting forward a kind of economical, effective PR-amended cutoff wall.