酸污染原状黄土渗透微观特征演变规律试验研究

研究污染黄土的渗透特性能够为污染场地的治理提供经济高效的方案措施。以蒸馏水作为渗液,采用GDS三轴渗透仪通过室内试验研究了盐酸、硝酸和硫酸侵蚀黄土的渗透特性变化规律,并从微观结构的变化进行机制分析。试验结果表明:相同固结应力条件下,不同类型污染土的渗透系数均随酸液浓度的增大而降低;随着酸液浓度增大,污染土骨架连接方式由点-点接触向点-面接触、面-面接触转变,土体内部大孔隙消散、小孔隙增多使得有效渗流孔隙减少,导致污染土渗透系数降低;相同试验条件下不同类型污染土渗透性能变化规律为:硫酸<硝酸<盐酸<水,即酸液增强了黄土防渗及防污性能。研究结果以期为黄土地区的工程活动和防污治理提供有效参考。

Experimental study on evolution of micro-permeability characteristics of acid-contaminated undisturbed loess

Studying the permeability characteristics of acid-contaminated undisturbed loess can provide cost-effective engineering measures for the treatment of contaminated sites. Distilled water was used as the exudate. The permeability variation of the undisturbed loess was studied by using GDS triaxial permeameter under erosion by hydrochloric acid, nitric acid and sulfuric acid. The mechanism analysis was carried out from the change of microstructure of acid-contaminated undisturbed loess. The test results show that under the same consolidation stress conditions, the permeability coefficients of different types of contaminated undisturbed loess decrease with the increase of acid concentration. As the of acid concentration increases, the connection mode of contaminated undisturbed loess skeletons changes from point-to-point contact to point-to-surface contact and surface-to-surface contact. The dissipation of large pores and the increase of small pores decreases the effective seepage pores, and therefore decreases the permeability coefficient of the contaminated undisturbed loess. Under the same experimental conditions, the sequence of the permeability of different types of contaminated undisturbed loess is: sulfuric acid