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Article
Plug Length Developed in Pipe Pile Embedded Within Partially Saturated Cohesionless Soils (Part 1)

Authors: Ali M. AL-Gharbawee --- Karim H. Ibrahim Al -Helo --- Mahmood Rashid Mahmood
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 7 Part (A) Engineering Pages: 1335-1346
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This paper presents an experimental study to investigate the change of plug length for pipe pile under different state of saturation and investigate the effect of number of pipe piles on plug length. The influence of matric suction (i.e., capillary stresses) in unsaturated zone is typically considered on the plug length of pipe piles.The experimental work consist of testing 20 models of pipe piles, these models divided into 4 different configuration of pipe piles; single pipe pile, group of double pipe piles, group of triple pipe piles and group of six pipe piles. All these models are loaded and tested under three different states; dry condition, fully saturated condition (i.e., matric suction equals to 0 kPa) and unsaturated conditions with three different matric suction values (6, 8 and 10 kPa), which are achieved by predetermined lowering of water table. The relationship between matric suction and depth of ground water table was measured in suction profile set by using three Tensiometers (IRROMETER). The soil, water characteristic curve (SWCC) was estimated by applying fitting methods through the program (Soil Vision).The results of experimental work demonstrate that the values of plug length decreased with increase in value of matric suction for the same configuration of pipe piles, and the values of plug length decreased with increase in number of pipe piles.


Article
Effect of Particle Size Distribution of Cohesionless Soil and Pile Diameter on the Behavior of Open Ended Pipe Piles

Authors: S.J. Abdullah --- M.R. Mahmood
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2017 Volume: 35 Issue: 1 Part (A) Engineering Pages: 83-90
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Pipe piles are normally used in deep foundations to transfer the structure load to stronger layer beneath the ground or to rock formations. More popular applications of pipe piles are marine construction (offshore structures), bridge piers construction and building construction. This research is conducted to study the effect of grain size distribution of cohesionless soil (i.e. fine, medium and coarse sand) on the ultimate load capacity of pipe piles with different diameters under dry and fully saturated state through an experimental model. Also, Degree of soil plugging behaviors for different pipe pile diameters and saturation conditions (i.e. dry, fully saturated conditions) for different particle size distribution was studied. Karbala sand, were used as a natural soil in the present study, it is poorly graded clean sand of rounded particles. The sandy soil is sieved to obtain a fine, medium and coarse graded according to (ASTM D 422-02). The experimental model tests conducted on four open-ended steel pipe piles models with diameters of (25, 30, 35 and 41mm) embedded within different grain size distribution of sand prepared under dry and fully saturated conditions with relative density of 65%. The results shows that, the ultimate load capacity of open-ended pipe piles embedded within medium grain size exerted higher bearing capacity than the other grain size distribution and increased with increasing piles diameters. The increasing values of the ultimate load carrying capacity for different pipe pile diameters under dry conditions are almost greater than that of saturated conditions by about (1.95-2.4) times for fine sand, (2.36-3.04) times for medium sand and (1.62-1.97) times for coarse sand. Furthermore, Plug Length Ratio PLR (which is the proportion of a soil plug length to the pile penetration depth) was measured for different pile diameters, and it was found that the length of soil column increases gradually with the increasing of a piles diameter


Article
Comparative Study of Bearing Loads for Open Ended Pipe and H-Piles in Sandy Soil

Authors: M.A.M. Al-Neami --- M.H. Wasmi
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2017 Volume: 35 Issue: 6 Part (A) Engineering Pages: 593-601
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This paper clarifies the response of steel piles installed in sand under vertical static compression load. To evaluate the ultimate load capacity of both piles, the results were introduced in a comparison form. Pile capacity of open ends pipe pile is affected by degree of soil plugging and sometimes the removal of soil plug may decrease the friction between soil and inner shaft of pile and causes a reduction in the load capacity. Therefore, to avoid plugging phenomenon occurred during piles installation; H-piles sections are manufactured based on the equivalent area steel of open pipe piles and tested under the same conditions. 36 steel piles with lengths equal to (30, 40, and 50) cm are tested. The piles are embedded using jacking technique in sandy samples with two different relative densities; medium sand (60%) and dense sand (80%).The results showed that H-pile has a load capacity greater than open ended pipe pile and increases with the increase in both length and diameter (width of flange) of pile. When relative density increased, plugging phenomenon does not occur in H-pile therefore, it can be used instead of open-ended pipe pile to get rid of plugging phenomenon problems.

Keywords

H-pile --- Pipe pile --- Soil plug --- Bearing load


Article
FINITE ELEMENT SIMULATION OF PLUGGED OPEN ENDED PILE BEHAVIOR
محاكاة بطريقة العناصر المحددة لسلوك الركائز مفتوحة النهايات ذات السدادة

Authors: Mohammed Y. Fattah محمد يوسف فتاح --- Nahla M. Salim نهلة محمد نوري سالم --- Asaad M. B. Al-Gharrawi اسعد محمد باقر
Journal: KUFA JOURNAL OF ENGINEERING مجلة الكوفة الهندسية ISSN: 25230018 Year: 2017 Volume: 8 Issue: 2 Pages: 1-17
Publisher: University of Kufa جامعة الكوفة

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Abstract

Open-ended steel pipe piles are widely used for foundations both on land and offshore because of low cost compare with other types of piles and it does not need a high effort for driving. During driving process of these piles into the soil, a soil column known as the soil plug is formed inside the pile. As the penetration continues, the frictional resistance between the inner pile shaft and the soil plug may be developed and in turn may prevent further soil intrusion. Depending on the relative movement between the pile and the soil plug, the pile is considered to be perfectly plugged, imperfectly plugged or unplugged. A numerical modeling of experiments was carried out using PLAXIS-2015 software, in which the Hardening Soil Model (HS small) has been used for soil modeling. During the verification problem used to simulate the experimental results of the pile group G2(2x2), the piles simulated as volume piles and steel cap were modeled using linear elastic model. The simulation showed that the maximum percentage of deviation between experimental and theoretical results is not more than 13.0%. This ratio is considered good when compared to the actual results and the theoretical results with the same values in some of the results.

تعتبر الركائز الأنبوبية الحديدية مفتوحة النهايات واسعة الاستعمال في الأسس عند اليابسة و في المنشآت البحرية وذلك لأنها رخيصة الثمن مقارنه بأنواع الركائز الاخرى ولا تحتاج الى جهد عالي عند تنفيذها. أثناء عملية الغرز لهذه الركائز في التربة يتكون عمود من التربة يعرف بسدادة التربة، و مع استمرار اختراق الركيزة يمكن أن تتنامى مقاومة الاحتكاك بين السطح الداخلي للركيزة و سدادة التربة مما ينتج عنه منع دخول مزيد من التربة. و اعتمادا على الحركة النسبية بين الركيزة و سدادة التربة تعتبر الركيزة إما مغلقة بشكل تام أو مغلقة بشكل غير تام أو غير مغلقة. PLAXIS تم إجراء تمثيل عددي لتجارب عملية باستعمال برنامج الحاسبة - حيث تم استعمال نموذج تصلب التربة 2015 لتمثيل التربة. و خلال مسألة التحقق التي استعملت لمحاكاة النتائج HARDENING SOIL MODEL (HS SMALL) PLAXIS ) ركيزة باستعمال البرنامج 2 X 2العملية لمجموعة ركائز مؤلفة من ( -، حيث تم تمثيل الركائز كركائز 2015 حجمية و تمثيل قبعة الركائز الخرسانية باستعمال نموذج مرن خطي. لقد بينت المحاكاة أن نسبة الانحراف العظمى بين النتائج العملية و النظرية لا تزيد عن 13% .

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