Şev stabilitesinin iki ve üç boyutlu modeller ile incelenmesi

Yıl 2015, Cilt: 6 Sayı: 1, 1 - 8, 01.06.2015

Taha Taşkıran Veysel Süleyman Yavuz Mehmet Salih Keskin

Öz

Bu çalışmada, sonlu elemanlar yönteminin, şev stabilitesi problemlerinin analizinde
uygulanabilirliği iki ve üç boyutlu modeller kullanılarak araştırılmıştır. Çalışmada, şevlerin
stabilitesinin sonlu elemanlar yöntemi ile analizinde kullanılan mukavemet azaltma tekniğinden
bahsedilmiş ve kumlu bir şev örneği ele alınarak göçmeye karşı güvenlik sayısı, mukavemet azaltma
tekniği kullanılarak elde edilmiştir. Çalışmada iki ve üç boyutlu modellemenin sonlu elemanlar
analizi üzerindeki etkileri araştırılmıştır. Ayrıca, limit denge yöntemi kullanılarak şev stabilite
analizleri gerçekleştirilmiş ve elde edilen güvenlik sayıları sonlu elemanlar yöntemi ile elde edilen
sonuçlarla karşılaştırılmıştır. Çalışma sonunda, üç boyutlu şev modeliyle elde edilen güvenlik sayısı
değerlerinin iki boyutlu durumda elde edilen değerden daha büyük olduğu ve mukavemet azaltma
tekniği ile elde edilen güvenlik sayısı değerlerinin, limit denge yöntemleri ile elde edilen güvenlik
sayısı değerleriyle uyum içerisinde olduğu görülmüştür.

Anahtar Kelimeler

Şev stabilitesi, Sonlu elemanlar yöntemi, Limit denge yöntemi, Güvenlik sayısı

Analysis of slope stability with two and three dimensional models

Öz

In this study, the applicability of the finite element
method in the analysis of slope stability problems
was investigated using two and three dimensional
models. Limit-equilibrium methods are the most
commonly used approaches for analyzing the
stability of slopes. The fundamental assumption at
their core is that failure occurs through sliding of a
block or mass along a slip surface. The popularity of
limit-equilibrium methods is primarily due to their
relative simplicity, ready ability to evaluate the
sensitivity of stability to various input parameters,
and the experience geotechnical engineers have
acquired over the years in interpreting calculated
factor of safety values. Limit-equilibrium methods
require minimal input data. The factor of safety
values they output help engineers to guard against
uncertainties such as ignorance about the reliability
of input parameters and loadings, and the possibility
that identified failure mechanisms may differ from
actual behaviour. As well, recommended factor of
safety values for slopes and excavations generally
ensure that deformations are within acceptable
range. Rapid advances in computer technology and
sustained development have pushed the finite
element method (FEM) and other numerical analysis
approaches to the forefront of geotechnical practice.
Since it was first applied to geotechnical
engineering in 1966, the FEM has grown
tremendously in popularity, primarily due to its
ability to analyze a very broad range of problems,
while yielding realistic results. It can accommodate
practically all kinds of geometry, and can model key
aspects of material behaviour such as stress paths
(construction sequence), and coupled stress-pore
pressure variations. In the mid 1970s, techniques for
applying the FEM to slope stability analysis started
appearing in geotechnical literature. They were
mostly based on an approach that flows naturally
from the definition of slope factor of safety, and is
now commonly referred to as the Shear Strength
Reduction (SSR) technique. By definition, the factor
of safety of a slope is the “ratio of actual soil shear
strength to the minimum shear strength required to
prevent failure,” or the factor by which soil shear
strength must be reduced to bring a slope to the
verge of failure (Duncan, 1996). Strength reduction
technique which is used in the analysis of slope
stability with finite element method is discussed and
an example of sand slope was considered to obtain
the factor of safety against the failure using strength
reduction technique. The strenght reduction analysis
was carried out with the using of the Plaxis
computer programme which is solved with the finite
element method. In the study, the effects of two and
three dimensional models on the finite element
analysis were investigated. Also, slope stability
analyses were performed using limit equilibrium
method and obtained results were compared with
finite element results. At the end of the study, it was
shown that the values of factor of safety (FS)
obtained from 3D model is higher than those of 2D
model and a satisfactory agreement was observed
between the results obtained from limit equilibrium
method.

Anahtar Kelimeler

Slope stability, Finite element method, Limit equilibrium method, Factor of safety