Tekrarlı Yük Etkisinde Kil Zeminlerin Lineer Olmayan Elastik Davranışı

Year 2009, Volume: 22 Issue: 1, 169 - 185, 30.06.2009

Volkan Okur Atilla Ansal

Abstract

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.

Keywords

Başlangıç kayma modülü, sönüm oranı, dinamik üç eksenli

Non-Linear Elastic Response Of Clay Soils Under Cyclic Loadings

Abstract

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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