Investigation of Effects of Excavations on Adjacent Foundations using Finite Element Modeling
No Thumbnail Available
Date
2016-01
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Deformations caused by excavations are important to determine because for the past decade, deep
excavations are becoming more common in Addis Ababa. Due to congestion of places, most of
these excavations are near adjacent buildings. Numerous high rise buildings are erected and the
effect of these on the adjacent grounds which in turn on adjacent foundations have not been studied
very thoroughly. The purpose of this master’s thesis is to first determine the effects of foundation
loads at different levels on a red clay soil and to see the effect on adjacent excavations as a result of
vertical and horizontal displacements. Four foundation levels are used by differentiating between
the numbers of their respective building basements: no basement, one basement, two basements and
three basements foundation levels. For the same foundation level, the distance from the edge of
excavation was also varied from 0m to 3.5m and to 7m. The variations of vertical and horizontal
displacements were plotted against the distance from the face of excavation. The results showed
that at 3.5m from the face of excavation and beyond that, the displacements decreased to a
minimum value. Similar trends are shown in the decrease of the vertical and horizontal
displacements for those cases with the same number of strut levels showing that the strut level will
affect the value of the deformation in spite of the vertical excavation level.
The second purpose is to determine the vertical and horizontal displacements of the ground and
wall under different cases by changing soil, wall and excavation properties by means of parametric
study. PLAXIS 3D Foundation V.1 was used as a tool to carry out all the analysis. The parameters
are varied for three levels of excavations i.e. 4.9m, 10.35m and 15m Final excavation. The modulus
of elasticity and the excavation depth showed prominent effect on the results. The allowable
deformation values from EBCS 7 and other literature have been compared with the cases with the
most critical deformation values. The result of the comparison is that those cases with low stiffness
modulus values resulted with high deformation exceeding the allowable values from previous
literatures.
Key words: Deformations, secant pile wall, PLAXIS, allowable values
Description
Keywords
Deformations;secant pile wall;PLAXIS; allowable values