Sızıntı Sıvıları ile Yıllandırılmış Geomembranların Ara Yüzey Kayma Dayanımı Davranışları

Öz

Sızdırmazlık, koruma ve ayırma gibi çeşitli mühendislik fonksiyonlarıyla kullanılan geomembranlar (GM), uzun vadede farklı sıvıların etkilerine maruz kalabilirler. Bu süreçte kimyasal yapılarında önemli ölçüde bir değişiklik olmazken, fiziksel ve mekanik özelliklerinde farklılıklar gözlenebilir. Bu değişiklikler kısa vadede göz ardı edilebilir ancak uzun vadede göz ardı edilmemelidir. Bu çalışmada, farklı sızıntı sıvılarında yıllandırılan GM ve zemin arasında oluşan ara yüzeylerin kayma dayanımı davranışları incelemiştir. Zemin olarak kum-bentonit (KB) karışımı kullanılırken, GM olarak yüksek yoğunluklu polietilen (HDPE) ve termoplastik poliolefin (TPO) kullanılmıştır. Çalışmanın ilk aşamasında, zeminin geoteknik indeks ve kayma mukavemeti parametreleri belirlenmiştir. İkinci aşamada ise, zemin – GM ara yüzeylerinin kayma mukavemeti davranışları hem yıllandırılmış hem de yıllandırılmamış GM’ler için belirlenmiştir. Saha koşullarını yansıtabilmek için laboratuvar koşullarında farklı sentetik atık sızıntı sıvıları (asidik maden drenaj sızıntı suyu (AMD), kömür yanma ürünü sızıntı suyu (CCP) ve kentsel katı atık sızıntı suyu (MSW)) hazırlanmıştır. GM'ler bu sızıntı sıvılarında 4 ve 16 ay boyunca yıllandırılmış ve ardından ara yüzey kesme kutusu deneyleri gerçekleştirilmiştir. Ara yüzey sürtünme açılarının tüm yıllandırma sıvılarından önemli ölçüde olumsuz etkilendiği tespit edilmiştir. AMD’nin GM'lerin arayüzey sürtünme açıları üzerinde en olumsuz etkiye sahip olduğu, CCP’nin ise en az hasara neden olduğu görülmüştür. Bu çalışma, tasarımlarda kullanılan ara yüzey sürtünme katsayılarının uzun vadede kimyasallara maruz kalan GM'ler için yeterli olmadığını göstermiştir.

Anahtar Kelimeler

• Ara Yüzey Kayma Dayanımı
• Geomembran
• Sızıntı Sıvısı
• Yıllandırma

Interface Shear Strength Behaviors of Geomembranes Aged with Leachates

Öz

Geomembranes (GM), used in various engineering functions, such as sealing, protection and separation, may be exposed to the effects of various liquids in the long term. In this process, while there is no significant change in their chemical structure, changes in their physical and mechanical properties can be observed. These changes can be ignored in the short term but not in the long term. In this study, the shear strength behaviors of the interfaces between GM and soil aged in different leachates was investigated. A sand-bentonite mixture was used as soil, while high density polyethylene (HDPE) and thermoplastic polyolefin (TPO) were used as GM. In the first stage of the study, the geotechnical index and shear strength parameters of the soil were determined. In the second stage, the shear strength behavior of the soil–GM interfaces was determined for both unaged and aged GMs. Different synthetic waste leachates (acidic mine drainage leachate (AMD), coal combustion product leachate (CCP) and municipal solid waste leachate (MSW)) were prepared under laboratory conditions to simulate field conditions. The GMs were aged in these leachates for 4 and 16 months and interface direct shear tests were performed. The interface friction angles were found to be significantly adversely affected by all aging liquids. AMD was found to have the most detrimental effect on the interface friction angles of GMs, while CCP caused the least damage. This study has shown that the interface coefficients used in the designs are not sufficient for GMs exposed to chemicals in the long term.

Anahtar Kelimeler

• Aging
• Geomembrane
• Interface Shear Strength
• Leachate

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