Engineering geological assesment of clayey soils in Ankara for being utilized as compacted clay liners

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Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Geological Engineering, Turkey

Approval Date: 1999

Thesis Language: English

Student: İLKER MET

Supervisor: HALUK AKGÜN

Open Archive Collection: AVESIS Open Access Collection

Abstract:

Clayey soils are considered as a source for compacted clay liners due to their low hydraulic conductivities and widespread distributions throughout the Ankara region. This study makes an attempt to determine the engineering geological properties and the compaction permeability characteristics of clayey soil samples obtained from three sites in the Ankara region. The index properties of the soil samples were determined. All of the soil samples were permeability tested at 2 to 4% on the wet sides of their optimum moisture contents through using falling head compaction permeameter apparatus. The mineralogy of the soil samples were examined by X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses. Cation exchange capacities (CEC) of the soil samples were determined by the Methylene Blue Adsorption Test in order to determine the presence of swelling clay minerals in the soil samples. Several landfill profiles containing geomembrane/clay composite lining systems were simulated by using the HELP model. Expected leakage rates through the bottommost compacted clay liners and the average heads acting on the bottom compacted clay liner were determined for each profile. Analyses indicate that sanitary landfill should contain leachate collection layers as well as geomembrane/clay composite lining systems. Moreover, usage of compacted clay liner in the cap cover system is essential to improve the long term performance. All of the soil samples tested herein have hydraulic conductivities lower than suggested limits of Turkish regulatory (1x1 0"8 m/s) and therefore they can be utilized as compacted clay liners in potential sanitary landfill sites. Key words: Compacted Clay Liner, Hydraulic Conductivity, Falling Head Permeability Testing, Expected Leakage Rate.