research centers


Search results: Found 2

Listing 1 - 2 of 2
Sort by

Article
Comparison between Sand Columns and Sand Columns Stabilized with Lime or Cement with Stone Columns Embedded in Soft Soil

Authors: Ahmed S.A. Al-Gharbawi --- Nawres A.A. Rajab
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 15 Part (A) Engineering Pages: 2805-2815
Publisher: University of Technology الجامعة التكنولوجية

Loading...
Loading...
Abstract

Sand and stone columns are used to improve bearing capacity of soft clayey soils… because of their stiffness which is higher than the soil was replaced, the compacted columns… produce shearing resistances which provide vertical support… for overlying structures… or embankments. Also the sand… and stone columns… accelerate the settlement… in the native surrounding soil… and improve the load settlement… characteristics… of foundation. The technique… consists of excavating… holes of specific… dimensions and arrangement… in the soft soil… and backfilling… them with either… sand or… stone particles. The present work investigates the behavior of soft soil reinforced with group of stone columns, sand columns and sand columns stabilized with lime or cement. The percentage of lime and cement used in this research, were determined previously in papers of single sand column stabilized with lime and cement, 11% by weight lime and 9% by weight cement. The model tests were carried out on a soil with undrained shear strength ranging between 16-18 kPa. The models consist of eight… columns at area replacement ratio of (0.196) in square pattern, the holes 50 mm in… diameter and 300 mm… in length were excavated… in a bed… of soft soil. The holes… were backfilled… with stone, sand and sand… stabilized with lime or cement particles. Each group… of columns was loaded… gradually through… a rectangular… rigid footing, its dimensions… 400×200 mm with 50 mm thickness, up to failure… with continuous… monitoring of the settlement. The test… results are analyzed… in terms… of bearing improvement… ratio… and settlement reduction… ratio for all… columns… and in terms… of the stress… concentration… ratio and… stiffness ratio. The results show that the improvement in bearing capacity was about 70% and 62% for sand columns stabilized by lime and cement respectively, and the improvement in bearing capacity was about 42% and 34% for sand columns stabilized by lime and cement compared with stone columns respectively.


Article
Treatment of Soft Soil by Sand Columns
معالجة التربة الطينية الضعيفة بواسطة الأعمدة الرملية

Authors: Namir K.S. Al-Saoudi --- Mohammad M. M. Al-Kaissi --- Nawres A. A. Rajab
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2014 Volume: 32 Issue: 9 Part (A) Engineering Pages: 2106-2118
Publisher: University of Technology الجامعة التكنولوجية

Loading...
Loading...
Abstract

Stone or sand columns are most widely used to improve the engineering properties of soft saturated soils. In principles, sand columns technique is very close to the well-known stone columns technique and the only difference is the backfill materials. The present work focuses on implementing sand columns in soft soil of different diameters, different relative densities considering both floating and end bearing types. The model tests were performed inside a steel container (600mm x 600mm and 500mm in height). Sand columns of diameters ranging between 22mm to 50mm were constructed in beds of soil of undrained shear strength ranging between (15-20) kPa. Each individual sand column was loaded vertically through a rigid circular footing of diameters between 28.6mm to 64.7mm provided an area replacement ratio (as) of (0.6),the ratio of column depth to the column diameter (L/D) was (6).The model test results revealed good improvements of the load carrying capacity of the columns ranging between (1.3 to 1.9) and significant reduction in the settlement over the untreated soil ranging between (0.18 to 0.47). End bearing columns exhibited better results than floating columns and the diameter of column has no effect on bearing capacity as the (as) and (L/D) are constants

تقنية الأعمدة الحجرية أو الأعمدة الرملية تستخدم بصورة واسعة لتحسين الخواص الهندسية للترب الطينية المشبعة الضعيفة. تتشابه الأعمدة الرملية من حيث المبدأ مع الأعمدة الحجرية والفرق الوحيد هو المواد المستخدمة في ملئ الأعمدة. يركز البحث الحالي على غرز الأعمدة الرملية في تربة طينية ضعيفة وبأقطار مختلفة, بكثافات نسبية مختلفة مع الأخذ بنظر الاعتبار نوعية الأعمدة الطافية وأعمدة التحمل الطرفي.أُجريتالنماذج المختبرية بداخل صندوق حديدي بأبعاد (600 ملم*600 ملم وبارتفاع 500 ملم). نُفذت الأعمدة الرملية بأقطار تتراوح بين 22 ملم الى 50 ملم بداخل تربة طينية ذات مقاومة قص غير مبزول يتراوح بين (15-20) كيلو باسكال. كل الأعمدة الرملية مفردة وحملت بطريقة عمودية بواسطة أساسات دائرية صلبة تتراوح أقطارها بين 28.6 ملم الى 64.7 ملم مع الأخذ بنظر الأعتبار تثبيت نسبة المساحة الأستبدالية تساوي (0.6),نسبة طول العمود الى قطره تساوي (6). أظهرت نتائج الفحوصات المختبرية تحسين جيد لقابلية التحمل يترواح بين (1.3 الى 1.9) وتقليل ملحوظ للهطول يتراوح بين (0.18 الى 0.47), أعمدة التحمل الطرفي افضل من الاعمدة الطافية, لايؤثر قطر العمود على قابلية التحمل في حال تثبيت نسبتي المساحة الأستبدالية وطول العمود الى قطره.

Listing 1 - 2 of 2
Sort by
Narrow your search

Resource type

article (2)


Language

English (2)


Year
From To Submit

2016 (1)

2014 (1)