Tekrarlı Yük Etkisinde Kil Zeminlerin Lineer Olmayan Elastik Davranışı

Zemin tabakaların dinamik yükler altındaki davranışı, tekrarlı yükleme genliğine bağlı olarak farklılıklar göstermektedir. Bu çalışmada, İstanbul Avcılar Bölgesinden alınan örselenmemiş kil zemin numuneler üzerinde, gerilme kontrollü dinamik üç eksenli deneyler yapılmıştır. Normal konsolide olarak hazırlanan numuneler 0,1 Hz frekansında, farklı tekrarlı gerilme genliklerinde yüklenmiştir. Yükleme sonucu maksimum kayma modülü, sönüm oranı değerleri belirlenmiştir. Lineer olmayan elastik davranış sınırı kayma modülü oranının yaklaşık % 90 değerine denk gelmektedir. Bu sınır aşıldıktan sonra malzemenin tekrarlı yük altında davranışı, özellikle plastisite indisinden büyük oranda etkilenmektedir. Deney sonuçlarından, maksimum kayma modülünü belirlemeye yönelik pratik amaçlar için kullanılabilecek bağıntılar önerilmiştir. Ayrıca arazi deneylerinden elde edilen kayma dalgası hızından yola çıkarak laboratuar ve arazi kayma modülü ve sönüm oranı arasındaki ilişki belirlenmiştir.

Anahtar Kelimeler:

Başlangıç kayma modülü, sönüm oranı, dinamik üç eksenli

Non-Linear Elastic Response Of Clay Soils Under Cyclic Loadings

Response of soil deposits under dynamic loadings differs with the cyclic loading amplitudes. In this study, stress controlled cyclic triaxial tests were conducted on the specimens taken from the Istanbul Avcilar District. Normally consolidated specimens were cyclically loaded under different stress amplitudes at a frequency of 0.1 Hz. Maximum shear modulus and damping ratio values determined. Loading cycles showed that the non-linear elastic shear modulus is approximately equal to 90% of shear modulus ratio. After this threshold it’s observed that the material response under cyclic loading is greatly influenced from plasticity index of the soil. From the test results empirical relationships proposed for determining the maximum shear modulus for practical purposes. Furthermore, a correlation for field conditions is also presented by using in situ shear wave velocities between laboratory and in-situ shear modulus and damping ratio values.

Keywords:

Initial shear modulus, damping ratio, dynamic triaxial,

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