Experimental and numerical investigations of foundation vibrations

Dissertant

al-Wakil, Sad Fayiq Abbas

Thesis advisor

Fattah, Muhammad Yusuf
Karim, Husayn Hamid

University

University of Technology

Faculty

-

Department

Department of Building and Construction Engineering

University Country

Iraq

Degree

Ph.D.

Degree Date

2010

English Abstract

This thesis deals with the dynamic analysis of foundations on fully saturated soil experimentally and numerically by the finite element method.

The numerical analysis involves the displacement-pore fluid pressure formulation of the dynamic consolidation theory to represent the saturated soil under the effect of dynamic loadings of harmonic vertical mode of vibration.

In this thesis, a new model is developed to represent the elasto-plastic behavior of the saturated soil under the dynamic loadings based on the Drucker-Prager plasticity model.

The dilation slope of the plastic potential surface is derived as a function of the angle of internal friction of the soil and it is considered as a constant parameter of the plasticity model, and this assumption is proposed in order to make the material hardening dependent on the angle of friction.

The developed model indicates that the dynamic response of the solid displacement and pore pressure from the elasto-plastic behavior is larger than that assuming elastic behavior of the soil for the same values of the dynamic loadings.

Several methods are available to determine the dynamic response of machine foundations; all of these methods consider the soil under the foundation is dry.

In this work, a small scale footing model is performed to simulate a physical model of machine foundation on saturated soil.

In addition, a numerical model is performed by using the finite element method for the applicability of the theory on the physical model.

The small scale footing model is performed to investigate the amplitude of displacement of rectangular footing on saturated sand under the effect of the harmonic vertical mode of vibration.

The numerical modeling in prototype scale using a three-dimensional formulation is adopted to simulate the physical model.

The results from the numerical model showed that a good agreement is achieved between the predicted dynamic response and the measured response of the physical model.

In this study, a method to model the semi-infinite extension (unbounded domain) of the saturated soil is developed.

In this method, the unbounded domain is replaced by an absorbing layer of finite thickness with properties that appreciably reduce the wave reflection into bounded domain.

In this layer, the soil is represented by the same properties as in the soil close to the foundation (bounded domain) and a model of frequency-dependent damping is implemented.

It found that a decay in wave can be noticed when the unbounded domain of the saturated soil is represented by the energy absorbing layer.

In addition, the maximum displacement of the foundation will be decreased due to using the energy absorbing layer to simulate the unbounded domain in comparison with the elementary boundaries.

The excess pore water pressure that developed during the dynamic loading will be dissipated with time due to using the energy absorbing layer.

Main Subjects

Physics

Topics

• Construction engineering
• Freemasonry
• Mechanics
• Soil physics
• Soil mechanics
• Architecture
• Walls

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-304999