The dynamic behavior of machine foundation on saturated sand

مقدم أطروحة جامعية

Abd al-Karim, Khalid Walid

مشرف أطروحة جامعية

Salim, Nahlah Muhammad Nuri
Ruhayl, Falah Hasan

الجامعة

الجامعة التكنولوجية

الكلية

-

القسم الأكاديمي

قسم هندسة البناء و الإنشاءات

دولة الجامعة

العراق

الدرجة العلمية

ماجستير

تاريخ الدرجة العلمية

2013

الملخص الإنجليزي

The design of the vibratory machine foundation is more complex than that of a foundation which supports only static load.

In machine foundation, the designer must consider in addition to the static load, the dynamic load caused by the working of the machine.

Therefore, the designer should be well conversant with the problem concerning dynamic behavior of the foundation and the soil underneath.

In general most of the settlement in saturated sandy soil under static load completed by the time construction is occurs.

When the soil is subjected to dynamic load, it will suffer excessive settlement and great losses of strength due to the tendency of soil to densify and buildup of excess pore water pressure, consequently the effective stress will decrease and a great damage can occur.

This study focuses on the effect of machine vibration on the variation of excess pore water pressure and settlement of saturated sand.

Also the variation of safety factor was studied.

A special setup is designed and manufactures to simulate the vertical vibration of the machine.

A total number of 42 model tests are conducted on sand using three relative densities (35, 60 and 85%) representing loose, medium and dense sand respectively.

For comparison, six models were conducted, three of them, which were performed on saturated sand, are test under static load and the others, performed on dry sand, were tested under dynamic load.

Different load amplitudes (0.4, 0.6 and 0.8 kN) under different frequencies (0.16, 0.5, 1 and 2 Hz) are used.

The results show that, the settlement increases for saturated soil models comparable with that of dry soil models and the maximum increment approximately approaches 20%.

Also, the settlement in saturated sand under vibrating load increases with increasing load amplitude while it decreases with increasing frequency and relative density.

But the rate of settlement ratio decreases as the load increment increases, the maximum increase in settlement ratio reaches about 36% when the load amplitude changes from 0.4 t0 0.6 kN while it is only reaches 21% when the load amplitude changes from 0.6 to 0.8 kN.

The excess pore water pressure increases with increasing the load amplitude, frequency and relative density.

The rate of change in excess pore water pressure increases about 30% as the load amplitude increases from 0.4 kN to 0.6 kN while it increases only 21 % when the load amplitude increases from 0.6 kN to 0.8 kN under the same frequency and relative density.

The safety factor is then determined as the ratio of the applied load at failure divided by the corresponding applied load from the static of loose sand model.

The factor of safety decreases with decreasing the relative density and frequency and increasing the load amplitude under the same number of cycles.

التخصصات الرئيسية

الهندسة المدنية

الموضوعات

• الميكانيكا
• فيزياء التربة
• ميكانيكا التربة

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-418061