Effect of external load on osmotic compression in clay soils

Öz

Clay soils that have not been exposed to saltwater can come into contact with brine due to saltwater flooding, sewage intrusion, or similar events. Additional settlements can occur in clays that subsequently interact with brine, driven by the osmotic effect. To investigate this, a series of odometer experiments were conducted on two natural clay samples: one with low plasticity (CL) and one with high plasticity (CH). The low-plasticity samples predominantly contained minerals from the kaolin group, while the high-plasticity samples were rich in minerals from the smectite group. The samples, prepared with distilled water, were exposed to brine solutions of varying concentrations (0.1M, 0.25M, 1M, and 2M NaCl and CaCl₂) under specific consolidation pressures (12.5 kPa, 50 kPa, and 200 kPa), simulating osmotically compressed soils. Structural and fabric alterations were examined using SEM images and EDX data collected from the tested samples. It was observed that mechanical forces were the primary factor in the compression of low-plasticity clay, which exhibited minimal fabric changes under the influence of salt. Consequently, osmotic-induced compression and fabric alterations were negligible. For the high-plasticity samples (with high smectite content), the highest osmotic compression was recorded at 50 kPa. These findings highlight the importance of balancing structural stress caused by external loads with osmotic forces.

Anahtar Kelimeler

• Clay–chemical interaction
• time-dependent deformation
• osmotic compression
• physicochemical effect
• SEM
• microstructure

Kil zeminlerde harici yükün ozmotik sikişmaya etkisi

Öz

Kil türü zeminler, tuzlu su taşkınları, kanalizasyon sızıntısı vb. nedeniyle tuzlu su ile temas edebilir. Daha sonra tuzlu su ile etkileşime giren killerde ozmotik etkiyle ilave oturmalar meydana gelebilir. Bu amaçla biri düşük plastisiteli (CL) ve diğeri yüksek plastisiteli (CH) olmak üzere iki doğal kil numunesi üzerinde bir dizi ödometre deneyi yapıldı. Düşük plastisiteli numuneler yüksek kaolin grubu mineral içeriğine sahipken, yüksek plastisiteli numuneler yüksek smektit grubu mineral içeriğine sahiptir. Saf su ile hazırlanan ve belirli konsolidasyon basınçlarına kadar (12.5kPa, 50kPa ve 200kPa) yüklenen numuneler tuzlu su çözeltilerine (0.1M, 0.25M, 1M ve 2M NaCl ve CaCl2 çözeltileri) maruz bırakılmış ve yük altında ozmotik sıkışma davranışları incelenmiştir. Deneyler tamamlanan numunelerden elde edilen SEM görüntüleri ve EDX verileri kullanılarak yapısal ve dokusal değişiklikler incelenmeye çalışılmıştır. Dokusu tuzun etkisiyle değişikliğe uğramayan düşük plastisiteli kilin sıkıştırılmasında mekanik kuvvetlerin baskın olduğu gözlemlenmiştir. Bu nedenle ozmotik kaynaklı sıkışma ve doku değişiklikleri ihmal edilebilecek seviyelerde gözlenmiştir. Yüksek plastisiteli numunede (yüksek smektit içeriği) en yüksek ozmotik sıkışmanın 50 kPa'da meydana geldiği gözlenmiştir. Bu nedenle dış yüklerin ve ozmotik kuvvetlerin neden olduğu yapısal yük dengesinin önemli olduğunu ortaya konmuştur.

Anahtar Kelimeler

• Kil-kimyasal etkileşimi
• zamana bağlı deformasyon
• osmotik sıkışma
• fizikokimyasal etki
• SEM
• mikro-yapı.

Kaynakça

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