膨润土改性黄土衬里防渗性能室内测试与预测  

Laboratory measurement and prediction to the permeability of bentonite-modified loess as a landfill liner

作　　者：张虎元[1] 赵天宇[1] 吴军荣 严耿升[1] 冯蕾[1] 

机构地区：[1]兰州大学西部灾害与环境力学教育部重点实验室,兰州730000 [2]中国市政工程西北设计研究院有限公司,兰州730000

出　　处：《岩土力学》2011年第7期1963-1969,1974,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.50678075);中国建筑股份有限公司项目(No.CSCEC-2008-Z-21)

摘　　要：试验测定了膨润土改性黄土试样的渗透系数,研究膨润土改性黄土用作废弃物填埋场衬里的可行性,为天然黏土匮乏地区防渗材料本土化提供依据。选取两种代表性黄土,即黏性较大的兰州黄土(LH)和砂性较大的榆林黄土(YH),分别向其中添加不同比例的两种膨润土后击实成样,利用柔性壁渗透仪测定改性黄土的渗透系数,分析了改性黄土渗透系数随膨润土添加率增大的变化规律,确定了满足衬里防渗要求的膨润土添加率。利用扫描电镜照片统计了改性黄土的孔隙特征参数,发现添加膨润土后黄土中原有的大孔隙被充填或分隔成更多的中、小孔隙,有效阻滞了渗流液体通过,从微观结构的角度揭示了改性黄土渗透性降低的实质。依据实测数据建立了膨润土改性黄土的渗透回归模型,据此可以预测不同添加量的膨润土改性黄土的渗透系数。Mixing of bentonite to a native soil is a convenient and economic means to make an impermeable earthen liner for landfills in a region where natural clay is deficient. In this investigation, laboratory permeability tests were conducted on the compacted specimens of loess and bentonite mixtures to study the feasibility of bentonite-modified loess as a landfill liner material. Two kinds of loess soils with different grain size compositions, the Lanzhou loess soil （LH） and Yulin loess soil （YH）, were mixed with various contents of bentonite, and compacted to the maximum density for the measurement of permeability by a flexible-wall permeameter. The variation relationship between permeability coefficient and bentonite addition levels was analyzed; and the minimum addition of bentonite to loess soils was determined with respect to the regulations to MSW landfill liner. Scanning electronic microscopy （SEM） was conducted to observe the microstructure of the compacted loess soils with different contents of bentonite addition. It was found that the larger pores existed originally in loess soils were transformed into a larger number of small pores by bentonite addition, which is mainly responsible for the reduction of soil permeability. Based on the test data, a regression penetrative model governing the permeability and the bentonite addition was established for practical prediction.

关 键 词：改性黄土 膨润土 渗透 衬里 废弃物填埋 

分 类 号：TU411.2[建筑科学—岩土工程]