Physical Modelling of Stresses Affecting the Walls of Tensile Cracks in Embankment Dams

Abstract

The safety of embankment dams is threatened by internal erosion, defined as the transporting materials used in their construction by water flow. One of the types of internal erosion, such as Concentrated Leak Erosion that occurs in tension cracks that develop in clay soils used in impervious zone construction, is controlled by hydraulic parameters related to the depth and width of the tension crack. Also, material properties, including the clay soil's internal erosion resistance, are considered. This study produced a new approach by utilizing the crack mechanism in an embankment dam to evaluate the stress conditions developing in the crack walls after cracking. To physically model this approach under laboratory conditions, a new test equipment was designed with the help of numerical analysis, i.e., Modified Stress Control Triaxial Equipment (MSCTE). The principal stress conditions occurring based on total stress in the post-cracking walls of tensile cracks with fully vertical and fully horizontal walls could be created under laboratory conditions with this test equipment. Tensile cracks developing in embankment dams were modeled with a circular hole formed in a cylindrical soil sample. Thus, by utilizing the mechanics of hollow cylindrical materials, the post-cracking wall stresses of tensile cracks can be explained by the stresses developing on the wall of the circular hole.

Keywords

• Crack
• embankment dam
• internal erosion
• ansys workbench
• triaxial stress

Dolgu Barajlarda Çekme Çatlaklarının Duvarına Etkiyen Gerilmelerin Fiziksel Olarak Modellenmesi

Abstract

Dolgu barajların güvenliği, inşaatında kullanılan malzemelerin su akımıyla taşınması olarak tanımlanan içsel erozyon ile tehdit edilmektedir. Özellikle geçirimsiz perde inşaatında kullanılan kil zeminlerde gelişen çekme çatlaklarında oluşan içsel erozyon türlerinden olan kaçak erozyon, çekme çatlağının derinliği ve genişliği ile ilgili hidrolik parametrelerle kontrol edilir. Ek olarak kil zeminin içsel erozyon direncini kapsayan malzeme özellikleri de göz önünde tutulur. Bu çalışmada bu kontrol faktörlerine ilave olarak çatlama sonrası çatlak duvarlarında gelişen gerilme koşullarının da dikkate alınabilmesi için dolgu barajlardaki çatlak mekanizmasından faydalanılarak yeni bir yaklaşım üretilmiştir. Bu yaklaşımın da laboratuvar koşullarında fiziksel olarak modellenebilmesi için nümerik analiz yardımıyla yeni bir test cihazı; Modifiye Edilmiş Gerilme Kontrollü Üç Eksenli Test Cihazı (MGÜET), tanımlanmıştır. Duvarları tam düşey ve tam yatayda olan çekme çatlaklarının çatlama sonrası duvarlarında toplam gerilme esasında oluşan asal gerilme koşulları, bu test cihazıyla laboratuvar koşullarında oluşturulabilmiştir. Dolgu barajlarda gelişen çekme çatlakları, silindirik zemin örneğinde oluşturulan dairesel bir delik ile modellenmiştir. Böylece, içi boş silindirik cisimlerin mekaniğinden faydalanılarak çekme çatlaklarının çatlama sonrası duvar gerilmeleri, dairesel deliğin duvarında gelişen gerilmeler ile açıklanabilmektedir.

Keywords

• Çatlak
• dolgu baraj
• içsel erozyon
• ansys workbench
• üç eksenli gerilme

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