Numerical analysis of machine foundation on saturated sandy soil

مقدم أطروحة جامعية

al-Shammari, Wouroud Talib Subayh

مشرف أطروحة جامعية

Salim, Nahlah Muhammad Nuri
Fattah, Muhammad Yusuf

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم هندسة البناء و الإنشاءات

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2013

الملخص الإنجليزي

Machine foundation resting on saturated porous medium is considered as a complicated geotechnical problem due to nature of dynamic loads and plasticity of soil which make the analysis and design of foundation subjected to dynamic loads more complex.

The main criteria for safe performance of machine foundations subjected to dynamic loads are to control excessive displacements.

In this thesis, a dynamic analysis of strip machine foundation with multiple thicknesses is placed at the middle of the top surface of saturated sand with different states (i.e.

loose, medium and dense), and vertical harmonic excitation is carried out with assessment of liquefaction potential and building up of the excess pore water pressure.

The dynamic analysis is performed numerically by using finite element software, PLAXIS 2D.

The soil is assumed as elastic perfectly plastic material obeys Mohr-Coulomb yield criterion.

To verify the abilities of PLAXIS 2D program in predicting the dynamic response (displacement and excess pore water pressure) of soil due to machine vibration, analysis of previously solved problems is carried out and good agreement is noticed by comparing the results obtained from this program and results from previous studies.

A parametric study is carried out to evaluate the dependency of machine foundation on various parameters including the amplitude of the dynamic load, the frequency of the dynamic load, the damping of soil mass, the thickness of the foundation, and the embedment of foundation.

The dynamic response (displacement and excess pore water pressure) generally increases with increasing of loading amplitude, but the displacement and excess pore water pressure versus frequency are not smooth and exhibit undulations (peaks and troughs).

It was found that, for all amplitudes and frequencies ranges considered in the parametric study, liquefaction forms first near the end of the adjacency to the surface at shallow depth of the sand at any relative density.

It was noticed that, increasing the embedment depth causes a reduction in the dynamic response up to a certain embedment depth; when the depth of embedment increases higher than (1m) the effect becomes less pronounced and as strength of the soil increases, the effect of embedment depth in reducing dynamic response will decrease also.

The vertical displacements decrease obviously by (46%, 37%, and 40%) for loose, medium and dense sand respectively when increasing the embedment of foundation from (0.5 m) to (1 m), while when the embedment of foundation increases from (1 m to 1.5 m), the vertical displacements for loose, medium and dense sand decrease by (45%, 38%, and 3%) respectively.

Finally, when the embedment of foundation increases from 1.5 m to 2 m, the decrements in vertical displacements are also recorded for loose, medium and dense sand by (42%, 36%, and 18%), respectively.

By considering soil damping in the analysis, it was found that soil damping will strongly affect the results of displacement and excess pore water pressure when the soil plasticity is involved in the analysis (i.e.

using elastic-plastic model).

التخصصات الرئيسية

العلوم الهندسية والتكنولوجية (متداخلة التخصصات)

الموضوعات

• هندسة الإنشاءات
• الماسونية
• ميكانيكا التربة
• التربة الرملية
• الهندسة المعمارية
• الجدران

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-418546