Gerilme Kontrollü Dinamik Üç Eksenli Deneyler ile Temiz Kumun Sıvılaşma Davranışının Belirlenmesi

Gevşek halde bulunan kohezyonsuz zeminler, sismik yükler altında ön veya tam sıvılaşmaya maruz kalarak önemli yapısal hasara neden olabilmektedir. Geoteknik deprem mühendisliğinde, kumlu zeminlerin sıvılaşma davranışı, genellikle drenajsız koşullarda gerçekleştirilen gerilme kontrollü döngülü laboratuvar deneyleri ile belirlenmektedir. Bu çalışmada, yeniden oluşturulmuş doymuş temiz kum numuneleri üzerinde bir dizi gerilme kontrollü dinamik üç eksenli testler gerçekleştirilmiştir. Farklı rölatif sıkılıkta (%38 - 90) hazırlanmış numuneler 0.1 Hz veya 1 Hz yükleme frekansına ve farklı tekrarlı gerilme genliği oranına (CSR) sahip gerilmelere maruz bırakılmıştır. Benzer rölatif sıkılık ve tekrarlı gerilme genliği oranı ile farklı yükleme frekansında (0.1 Hz ve 1 Hz) gerçekleştirilen deneylerde, sıvılaşmaya neden olan çevrim sayısının 1 Hz yükleme frekans değerinde daha faza olduğu görülmüştür. Bu sonuç, kum numunelerinin yüksek yükleme frekanslarında daha yüksek sıvılaşma mukavemetine sahip olduğunu göstermektedir. Ayrıca, döngüsel yükleme frekansından bağımsız olarak, artan relatif sıkılığın kum numunelerinin sıvılaşma direncini önemli derecede artırdığı tespit edilmiştir.

Anahtar Kelimeler:

Dinamik üç eksenli deney, Gerilme kontrollü testler, Sıvılaşma, Temiz kum

Stress-Controlled Dynamic Triaxial Experiments to Examine the Liquefaction Response of Clean Sand

Loosely packed cohesionless soils may suffer partial or complete liquefaction during seismic loading, causing significant structural damage. The dynamic behavior of liquefiable soils is widely investigated through element testing under controlled cyclic loading in undrained conditions. In this work, a total of 20 stress-controlled dynamic triaxial experiments were conducted on saturated specimens of clean sand to improve the understanding of the liquefaction phenomenon. The triaxial specimens were prepared at different relative densities in the range of 38 to 90% and subjected to varying cyclic stress ratios (CSR) with loading frequencies of 0.1 and/or 1 Hz. The experimental results indicated that under similar test conditions, the number of cycles needed for liquefaction was greater at 1 Hz than at 0.1 Hz, revealing that sand specimens exhibited higher liquefaction strength at higher loading frequencies. Furthermore, regardless of the cyclic loading frequency, the liquefaction resistance of sand increased with increasing densities.

Keywords:

Dynamic triaxial testing, Stress-controlled tests, Liquefaction, Clean sand,

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