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Register a new userNumerical Analysis and Model tests of the Bearing Capacity of shallow Strip Footing resting on Multi-layered Soils
دراسة مخبرية و عدديّة لقدرة تحمّل التربة لأساس سطحي مستمر متوضّع على تربة متعدّدة الطبقات
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Tishreen University ورقة بحثية
Publication date
2018
fields
Geotechnical Engineering
and research's language is
العربية
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Shamra Editor
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تمّ في هذا البحث محاولة حساب قدرة تحمّل التربة و الهبوط لأساس يخضع لحمولة مركزية شاقولية و مرتكز على تربة متعدّدة الطبقات و ذلك من خلال نماذج مخبريّة لأساس دائري متوضّع على تربة مكوّنة من عدّة طبقات و كذلك من خلال استخدام طريقة العناصر المنتهية (FEM) لحساب قدرة تحمّل التربة لأساس مستمر على تربة مكوّنة من طبقة واحدة و تربة مكوّنة من طبقتين (رمل و غضار), و من أجل دراسة تأثير عوامل متعدّدة على قدرة تحمّل التربة تمّ استخدام برنامج (PLAXIS V.8.6)، حيث تمّ نمذجة سلوك التربة المرن - اللدن من خلال قانون مور-كولومب (MC). من أجل حالة التربة المتجانسة أعطت مقارنة نتائج التجارب المخبريّة مع نتائج التحليل العددي و نتائج العلاقة النظرية تقارباً مقبولا.ً و من أجل حالة نموذج تربة مكوّنة من طبقتين (طبقة ضعيفة من غضار طري فوق طبقة قوية من رمل مرتص) تمّ إجراء دراسة متغيرات و أظهرت نتائج البحث أنّ قدرة تحمّل التربة تتناقص مع زيادة سماكة الطبقة الغضاريّة في حين أنّ الهبوط يزداد. و هناك عمق حرج لا يكون بعده تأثير للطبقة القويّة (الرمل) على قدرة تحمّل التربة و شكل موشور الانهيار.
In present investigation attempt has been made to study the bearing capacity and settlement characteristics of footings subjected to central vertical load and resting on layered soil with the help of model tests and with the application of finite element method (FEM) to calculate bearing capacity of a strip footing on one-layer and two-layer soil (Sand and Clay). To investigate the effect of various parameters on soil bearing Capacity a commercial finite element software, PLAXIS, has been used. Soil profile contains two soil types including sand and clay. Soil behavior is represented by the elasto-plastic Mohrcoulomb (MC) -model. For a one-layer case, the bearing capacity also is calculated which has a good agreement with theoretical equations. For a layered soil, soft-over strong soil, parametric study was carried out. It is concluded that the bearing capacity of footing decreases as the height of clayey soil increases whilst the displacement under footing increases. There is a critical depth where the stronger bottom layer does not affect ultimate bearing capacity and failure mechanism of footing.
References used
BOWLES, J. E. "Foundation Analysis and Design". 6th. ed., McGrow-Hill International Editions, (1998)
HANNA, A. M. & MEYERHOF, G. G. "Design Chats for Ultimate Bearing Capacity of Foundations on Sand Overlying Soft Clay ". Candian Geotechnical Journal, Vol. 17, n.2, (1980), pp.300-303
HANSEN, J. B. "A revised and extended formula for bearing capacity". Danish Geotechnical Institute, Copenhagen, In: Bulletin No. 28, (1970), pp. 5-11
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This research study aims at investigating the potential benefits of using the
reinforcement to improve the bearing capacity and reduce the settlement of strip footing on
clay. To implement this objective, many numerical 2D-analyses by finite elemen
t method /
Plaxis program were performed to study the behavior of reinforced soil foundation. And
then we carry out a parametric study of the most effective parameter on bearing capacity.
The results showed that the inclusion of reinforcement can significantly improve the soil’s
bearing capacity and reduce the footing settlement. The strain developed along the
reinforcement is directly related to the settlement. The results also showed that the
inclusion of reinforcement can redistribute the applied load to a wider area, thus
minimizing stress concentration and achieving a more uniform stress distribution. The
redistribution of stresses below the reinforced zone can result in reducing the settlement of
the underlying weak clayey soil.
This research study aims at investigating the potential benefits of using the reinforcement
to improve the bearing capacity and reduce the settlement of strip footing on clay. To
implement this objective, many numerical 2D-analyses by finite elemen
t method / Plaxis
program were performed to study the behavior of reinforced soil foundation. And then we
carry out a parametric study of the most effective parameter on bearing capacity. The
results showed that the inclusion of reinforcement can significantly improve the bearing
capacity and reduce the footing settlement. The strain developed along the reinforcement is
directly related to the settlement. The results also showed that the inclusion of
reinforcement can redistribute the applied load to a wider area, thus minimizing stress
concentration and achieving a more uniform stress distribution. The redistribution of
stresses below the reinforced zone can result in reducing the settlement of the underlying
weak clayey soil.
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