Kibria Golam, Hossain Md Sahadat
Drash Consultants, 1045 Central Parkway North, Suite 103, San Antonio, TX 78216, United States.
Department of Civil Engineering, University of Texas at Arlington, 417 Yates St, NH 404, Arlington, TX 76019, United States.
Waste Manag. 2015 May;39:197-204. doi: 10.1016/j.wasman.2015.02.015. Epub 2015 Mar 7.
During construction of compacted clay liners and evapotranspiration (ET) covers, quality control involves laboratory and field tests in individual lifts. However, the available methods may be inadequate to determine non-uniform compaction conditions, poor bonding of lifts, and/or variable soil composition. Moreover, the applicability of the available methods is restricted, in many instances, when spatial variability of the subsurface is expected. Resistivity Imaging (RI) is a geophysical method employed to investigate a large area in a rapid and non-destructive way. High resistivity of clay liner soil is an indication of a low degree of saturation, high air-filled voids, and poor lift bonding. To utilize RI as a quality control tool in a landfill liner, it is important to determine the saturation condition of the compacted soils because compaction and permeability of liner soil are functions of degrees of saturation. The objective of the present study is to evaluate the degree of saturation of a municipal solid waste (MSW) landfill liner, using RI. Electrical resistivity tests were performed in the laboratory, at varied moisture contents and dry unit weights, on four types of soil samples, i.e., highly plastic clay (CH), low plastic clay (CL), Ca-bentonite, and kaolinite. According to the experimental results, electrical resistivity of the specimens decreased as much as 15.3 times of initial value with increase in the degrees of saturation from 23% to 100%. In addition, cation exchange capacity (CEC) substantially affected resistivity. A multiple linear regression (MLR) model was developed to correlate electrical resistivity with degree of saturation and CEC using experimental results. Additionally, RI tests were conducted on compacted clay liners to determine the degrees of saturation, and predicted degrees of saturation were compared with the in-situ density tests. The study results indicated that the developed model can be utilized for liner soils having CEC, resistivity and degrees of saturation between 13.3 and 79cmol+/kg, and 2.6 and 504.3Ohmm, and 21.8% to 100%; respectively.
在压实粘土衬垫和蒸发蒸腾（ET）覆盖层的施工过程中，质量控制涉及对各分层进行实验室和现场测试。然而，现有的方法可能不足以确定压实不均匀的情况、分层之间的粘结不良以及/或者土壤成分的变化。此外，在许多情况下，当地下存在空间变异性时，现有方法的适用性会受到限制。电阻率成像（RI）是一种地球物理方法，用于快速且无损地探测大面积区域。粘土衬垫土壤的高电阻率表明饱和度低、空气孔隙率高以及分层粘结不良。要将RI用作垃圾填埋场衬垫的质量控制工具，确定压实土壤的饱和度状况很重要，因为衬垫土壤的压实度和渗透率是饱和度的函数。本研究的目的是利用RI评估城市固体废弃物（MSW）填埋场衬垫的饱和度。在实验室中，对四种土壤样品，即高塑性粘土（CH）、低塑性粘土（CL）、钙膨润土和高岭土，在不同含水量和干重度下进行了电阻率测试。根据实验结果，随着饱和度从23%增加到100%，试样的电阻率下降幅度高达初始值的15.3倍。此外，阳离子交换容量（CEC）对电阻率有显著影响。利用实验结果建立了一个多元线性回归（MLR）模型，将电阻率与饱和度和CEC相关联。此外，对压实粘土衬垫进行了RI测试以确定饱和度，并将预测的饱和度与现场密度测试结果进行了比较。研究结果表明，所建立的模型可用于CEC、电阻率和饱和度分别在13.3至79cmol + /kg、2.6至504.3Ω·m以及21.8%至100%之间的衬垫土壤。
