SERBEST VE RİJİT BAŞLI AÇIK DENİZ TEKİL KAZIK TEMELLERİNİN TEKRARLI YATAY YÜKLER ETKİSİ ALTINDAKİ DAVRANIŞI

Açık deniz tekil kazık temelleri rüzgar ve dalga kaynaklı ağır tekrarlı yatay yüklere maruz kalmaktadır. Bu yükler nedeniyle kalıcı zemin deplasmanları ve suya doygun zeminde aşırı boşluk suyu basıncı birikimi gerçekleşebilmektedir. Çalışmada serbest ve rijit başlı tekil kazık temellerinin tekrarlı yatay yükler altındaki davranışı sonlu elemanlar yöntemi ile zeminde aşırı boşluk suyu basıncı gelişimi ve deplasman birikimi dikkate alınarak incelenmiştir. Üç boyutlu sonlu elemanlar analizlerinde, zeminde aşırı boşluk suyu basıncı gelişiminin belirlenmesi amacıyla iki fazlı modele dayanan üç boyutlu elemanlar geliştirilmiştir. Böylelikle kazığın çevresindeki zeminde boşluk suyu basıncı gelişiminin elde edilmesi mümkün olmuştur. Kumlu zemin, tekrarlı yükler altındaki davranışının modellenmesine uygun olan bir hipoplastik malzeme modeli ile tanımlanmıştır. Nümerik analizlerde özellikle kazık, suya doygun zemin ve boşluk suyu basıncı etkileşimi üzerine odaklanmıştır. Analiz sonuçları, tekrarlı yatay yük etkisindeki serbest ve rijit başlı kazıkların deplasmanlarının tahmininde, suya doygun zeminde aşırı boşluk suyu basıncı gelişimini dikkate almayan mevcut modellerin yetersiz kaldığı göstermiştir.

Anahtar Kelimeler:

Tekil kazık, açık deniz, tekrarlı yatay yükleme, sonlu elemanlar yöntemi, serbest başlı tekil kazık, rijit başlı tekil kazık, kumlu zemin, kalıcı deformasyon, aşırı boşluk suyu basıncı

Behaviour of Free and Fixed-Head Offshore Piles Under Cyclic Lateral Loads

Offshore piles are subjected to cyclic lateral loads due to environmental loads, such as wind and waves. These loads can lead to an accumulation of permanent soil deformations and excess pore water pressures in saturated soils. Finite element analyses are performed to investigate the behaviour of cyclic laterally loaded free-head and fixed piles embedded in sandy saturated soil while considering such accumulation effects. A three-dimensional fully coupled two-phase finite element is developed and implemented on the basis of a two-phase model to consider the pore water pressure development in saturated soil. In addition, a hypoplastic constitutive model is used to describe the material behaviour of sandy soil under cyclic loading. In the numerical analyses, special attention is dedicated to interactions between the pile, the saturated soil and the pore water. The results have shown that the pile displacements caused by cyclic lateral loads are significantly underestimated for both pile head conditions by approaches which do not take into account the impact of the pore water pressure development in saturated sandy soil of the pile response.

Keywords:

Offshore piles cyclic lateral loading, finite element method, fixed-head pile, free-head pile, sandy soil, accumulation, permanent displacement, pore water pressure, two-phase model,

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