EFFECTIVE STRESS BASED NUMERICAL ANALYSIS OF LATERAL DEFORMATIONS DUE TO CYCLIC MOBILITY

Year 2011, Volume: 13 Issue: 2, 47 - 74, 01.05.2011

Devrim Erdoğan

Abstract

Cyclic mobility is a dynamic soil behaviour observed in saturated cohesionless soils under
dynamic loads in which large amounts of shear deformation is accumulated after initial liquefaction
and gives way to great lateral displacements. In this paper, one dimensional site response analyses
are carried out on medium and verd dense sand profiles under sinuzoidal lateral acceleration in order
to investigate numerically the development of cyclic mobility. The analyses are performed by using the
nonlinear finite element method in OPENSEES framework and the cyclic mobility behaviour is
represented by an effective stress based model called PDMY (Pressure Dependent Multi-Yield Surface
Plasticity ) model. The results of the study showed that the development of cyclic mobility behaviour is
strongly dependent on the relative density and initial effective stress conditions of the sand stratum,
driving shear stresses, residual strength and the duration, frequency and the amplitude of the dynamic
load

Keywords

Liquefaction, Flow liquefaction, Cyclic mobility

ÇEVRİMSEL HAREKETLİLİK DAVRANIŞINA BAĞLI YANAL ZEMİN DEFORMASYONLARININ EFEKTİF GERİLME TABANLI SAYISAL ANALİZİ

Abstract

Çevrimsel hareketlilik, dinamik yükler altındaki suya doygun kum zeminlerde, sıvılaşma meydana
geldikten sonra kayma deformasyonlarının birikmesi sonucunda yüksek düzeylerde yanal
yerdeğiştirmelerin oluşmasına neden olan dinamik bir zemin davranışıdır. Bu çalışmada, çevrimsel
hareketlilik davranışının oluşum sürecini sayısal olarak ortaya koymak amacı ile orta sıkı ve çok sıkı
suya doygun kum tabakalarına uygulanan sinüzoidal yanal yer ivmesi altında bir boyutlu zemin tepkisi
analizleri gerçekleştirilmiştir. Yapılan parametrik çalışmalarda sayısal analiz yöntemi olarak doğrusal
olmayan sonlu elemanlar yöntemi, çevrimsel hareketlilik davranışının temsil edilebilmesi için ise
efektif gerilme tabanlı bir zemin modeli olan PDMY (Pressure Dependent Multi-Yield Surface)
plastisite modeli kullanılmıştır. Analizler OPENSEES sonlu eleman açık kod ortamında
gerçekleştirilmiştir. Analizler sonucunda kum zeminin sıkılığı, başlangıç efektif gerilme durumu,
dinamik yükleme öncesinde maruz kaldığı statik kayma gerilmeleri, rezidüel kayma dayanımı ile
dinamik yüklemenin süresi, frekansı ve genliğinin çevrimsel hareketlilik davranışı üzerinde büyük
ölçüde etkili oldukları görülmüştür.

Keywords

Sıvılaşma, Akma sıvılaşması, Çevrimsel hareketlilik

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