Investigating the hydraulic conductivity and soil characteristics under compaction and soil texture and performances as

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ORIGINAL PAPER

Investigating the hydraulic conductivity and soil characteristics under compaction and soil texture and performances as landfill liner Omid Bahmani 1

&

Mansure Bayram 1

Received: 26 January 2018 / Accepted: 9 August 2018 # Saudi Society for Geosciences 2018

Abstract Soil compaction commonly used to minimize the leaching of pollutants into the soil and groundwater. This study expresses the results of an experimental method performed to investigate the influence of clay content and compaction conditions on the soil water retention cure parameters and saturated hydraulic conductivity of a proposed clay liner. Compacted samples of three soils with different clay percentages were prepared for different compaction energies (reduced (RC), standard (SC) and modified compaction (MC)) and different water contents (dry, wet, and optimum). The experimental data were fitted to four commonly models such as Brooks-Corey, Van Genuchten, Fredlund and Xing four-parameter and Fredlund and Xing five-parameter. Each model provided a satisfactory fit to the experimental data. R2 and RMSE ranged between 0.84 to 1 and 0.0002 to 0.051, respectively. In Van Genuchten model, the soils with higher plasticity index have lower α and larger n. However, the individual parameters obtained from the curve fit varied significantly among models. The hydraulic conductivity of the clay soil in modified compaction energy ranged between 8.8 × 10−7 and 1.5 × 10−6. Generally, the results indicated that soil compaction has increased the maintenance of soil water retention and also the modified compaction, dry of optimum, had the lowest Ks. Keywords Soil compaction . Fitting models . Saturated hydraulic conductivity . Landfill liner

Introduction Over the years, physical properties of the soil that control water movement and retention in the soils are largely affected due to human activities, engineering purpose and animal activities. Soil hydraulic properties play an important role in modeling water and solute movement within the vadose zone of soils (Wang et al. 2012). The soil used in engineering applications is compacted to achieve several desirable characteristics, among them an increase in shear strength and decreases in compressibility and hydraulic conductivity. Current laboratory procedures seek to define a maximum dry density and the optimum water content at which that density is reached using a constant compaction effort. As the optimum water content is approached, the dry density of the compacted soil increases and then decreases with additional added water in excess of the optimum water content. Optimum moisture content and * Omid Bahmani [email protected] 1

Department of Water Engineering, Faculty of Agriculture, Bu Ali Sina University, Hamedan, Iran

maximum dry density provide a baseline upon which other laboratory tests can be performed and construction practices judged. Generally to prevent the movement of pollution to groundwater, the compacted clay soils are used as barrier materials. The selection of these soils