رجوع

اجندة طالب الدراسات العليا

أسماء لجنة المناقشة:

1.       أ. د. محمد يوسف فتاح.        الجامعة التكنولوجية/هندسة البناء والإنشاءات       رئيسا

2.       أ.م. د. محمد عبد اللطيف محمود. الجامعة التكنولوجية/ هندسة البناء والإنشاءات  عضوا

3.       أ.م. د. جاسم محمد عباس.                جامعة ديالى / كلية الهندسة                    عضوا

4.       أ.م.د محمود رشيد محمود.     الجامعة التكنولوجية/هندسة البناء والأنشاءات      عضوا و مشرفا

اسم المقوم العلمي:  أ.م.د. محمود ذياب احمد.       جامعة بغداد / كلية الهندسة .    

اسم المقوم اللغوي:  أ.م.د. نجم عبد الكاظم الربيعي.     الجامعة التكنولوجية/هندسة تكنولوجيا النفط.

عنوان البحث للرسالة او الاطروحة:

Effect of Particle Size Distribution on the Behavior of Open Ended Pipe Piles in Cohesionless Soils under Different Saturation Conditions.

تأثير التوزيع الحبيبي على تصرف الركائز الانبوبية مفتوحة النهايات المغروزة في ترب غير متماسكة تحت ظروف تشبيع مختلفة

عناوين البحوث المستلة:

1.     Effect of Particle Size Distribution of Cohesionless Soils and Pile Diameters on the Behavior of Open Ended Pipe Piles

2.     Effect of Particle Size Distribution of Cohesionless Soils and Pile Diameters on the Behavior of Soil Column Inside the Open Ended Pipe Piles under Different Saturation Conditions.

تقدير المناقشة : أمتياز

مستخلص البحث

This research is conducted to study the effect of grain size distribution of cohesionless soil (i.e. natural, fine, medium and coarse sand) on the behavior of open-ended pipe pile with different diameters under various saturation conditions (i.e. dry, fully and partially saturated conditions) through experimental model study.

Karbala sand was used as a natural soil in the present study, it was poorly graded clean sand and most particles were  rounded. The sandy soil was sieved to obtain a fine, medium and coarse graded according to (ASTM D 422).

Total number of (83) models of steel pipe piles test, involving four open-ended steel pipe piles of (25, 30, 35 and 41mm) in diameter embedded to a depth of 400mm within (fine, medium, coarse and natural sand) which prepared with a predetermined relative density of 65%. All of these models were loaded and tested under each of dry condition, fully saturated condition and partially saturated conditions. Partially saturated conditions were achieved by lowering the water table to different levels below the soil surface (i.e. 150, 300 and 450mm), to achieve different suction values and get the relationships between matric suction value and depth of water table level. Matric suction was measured in suction profile technique by using two LT-Tensiometers (IRROMETER).

Steel loading frame was manufactured for this study to applied axial loading. Load cell was used to measure the applied load by connecting with digital weighing indicator to read and display the load value, and the settlement was measured by using two precise dial gauges.

Results of experimental work demonstrate that, the ultimate load capacity of open- ended piles was increased with increasing the piles diameter. The ultimate load capacity for pipe pile models under dry state are almost greater than those of saturated state. Also, under dry state the ultimate carrying capacity of pipe piles embedded within medium sand showing higher bearing capacity than the others grain size distribution (i.e. fine and coarse sand). However for unsaturated states, the ultimate carrying capacity of pipe pile was higher than those of saturated state and depends on matric suction values and lowering the water table level.

Furthermore, the plug length was measured for different pile diameters, and it was found that the length of soil column increased gradually with the increasing of a pipe pile diameters.  

The results of measuring dry unit weight and angle of internal friction for soil column inside the pipe pile models show that, the dry unit weight and angle of internal friction decreased linearly with increasing the pile diameters.

From soil water characteristic curves (SWCC) was estimated by applying fitting methods through the SOILVISION V.4 program for all the soils used, it was found that the larger particle size has a less magnitude of matric suction at the same value of water content, and the air-entry values increased with decreasing the median particle size (D₅₀). On the other hand, the boundary effect zone in (SWCC) increased with increasing the median particle size (D₅₀).

 Finally, the influence of soil grain size on the ultimate load capacity and plug length ratio of pipe pile models (i.e. scale factor effect) was studied, and  it shows a very small and negligible effect of particle size on the results of pipe piles models for cohesionless soils with poorly graded and rounded particles.

Key Words: Open ended pipe pile, particle size distribution, soil plug,   partially saturated.