Determination of Diameter of Belled Shafts with respect to Uplift Forces Resulted From Expansive Soil Layer in Active Zone

Year 2023, Issue 47, 53 - 60, 31.01.2023

İlyas ÖZKAN

https://doi.org/10.31590/ejosat.1243090

Abstract

Expansive soils are found in many parts of the world that are especially arid and semi-arid regions. They have caused several damages of lightweight structures for decades. For this reason, a more suitable foundation type should be selected and designed for the lightweight structures built on these soils. For example, the application of belled shaft foundation at expansive soil layer is preferable method in practice. However, one of the worst cases at the design of this foundation is accepted that the swelling of expansive soil placed in active zone. Therefore, this condition should be taken into account at the design process of this foundation. In this study, the diameter of belled shaft was separately determined with respect to some factors such as the diameter of shaft, the depth of active zone, the friction angle between shaft and soil, and the ratio between the undrained cohesion of soil at stable zone and the swelling pressure of expansive soil placed in active zone. In the calculation process, four different shaft diameters that are 0.3 m, 0. 45 m, 0.60 m, and 0.75 m were utilized. Also the depth of active zone that started from 1.5 m to 15 m was specified. To sum up, the optimum shaft diameter was found as 0.45 m.

Keywords

Belled shaft, Expansive soil, Active zone, Swelling pressure, Cohesion

Aktif Bölgedeki Şişen Zemin Tabakasından Kaynaklanan Kaldırma Kuvvetine Göre Genişletilmiş Şaftın Çapının Belirlenmesi

Abstract

Şişen zeminler, dünyanın birçok bölümünde özellikle yarı kurak ve kurak bölgelerinde bulunmaktadır. Bu zeminler, yılarca hafif yapılarda hasarlara neden olmaktadır. Bu yüzden, bu zeminlerin üzerine inşa edilecek yapılar için en uygun temel tipi seçilmeli ve tasarlanmalıdır. Örneğin, genişletilmiş şaft temel uygulaması pratikte tercih edilen bir metottur. Bununla birlikte, aktif bölgede yer alan şişen zeminin kabarması bu temel tasarımındaki en kötü senaryolardan bir tanesi olarak kabul edilmektedir. Bu yüzden bu temelin tasarım sürecinde bu durum göz önüne alınmalıdır. Bu çalışmada, genişletilmiş şaftın çapı; şaftın çapı, aktif bölge derinliği, şaft ve zemin arasındaki sürtünme açısı ve sağlam bölgedeki zeminin drenajsız kohezyonu ile aktif bölgede yer alan zeminin şişme basıncı arasındaki oran gibi faktörler dikkate alınarak ayrı ayrı hesaplanmıştır. Hesaplama sürecinde, dört farklı şaft çapı (0.3 m, 0. 45 m, 0.60 m ve 0.75 m) kullanıldı ayrıca 1.5 metre ile 15 metre arasında aktif bölge derinliği belirlendi. Özet olarak, optimum şaft çapı 0.45 m olarak bulunmuştur.

Keywords

Belled shaft, Expansive soil, Active zone, Swelling pressure, Cohesion

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